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Bibliography on: Microbial Ecology

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ESP: PubMed Auto Bibliography 12 Nov 2018 at 01:35 Created: 

Microbial Ecology

Wikipedia: Microbial Ecology (or environmental microbiology) is the ecology of microorganisms: their relationship with one another and with their environment. It concerns the three major domains of life — Eukaryota, Archaea, and Bacteria — as well as viruses. Microorganisms, by their omnipresence, impact the entire biosphere. Microbial life plays a primary role in regulating biogeochemical systems in virtually all of our planet's environments, including some of the most extreme, from frozen environments and acidic lakes, to hydrothermal vents at the bottom of deepest oceans, and some of the most familiar, such as the human small intestine. As a consequence of the quantitative magnitude of microbial life (Whitman and coworkers calculated 5.0×1030 cells, eight orders of magnitude greater than the number of stars in the observable universe) microbes, by virtue of their biomass alone, constitute a significant carbon sink. Aside from carbon fixation, microorganisms' key collective metabolic processes (including nitrogen fixation, methane metabolism, and sulfur metabolism) control global biogeochemical cycling. The immensity of microorganisms' production is such that, even in the total absence of eukaryotic life, these processes would likely continue unchanged.

Created with PubMed® Query: "microbial ecology" NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2018-11-10

Villegas-Plazas M, Wos-Oxley ML, Sanchez JA, et al (2018)

Variations in Microbial Diversity and Metabolite Profiles of the Tropical Marine Sponge Xestospongia muta with Season and Depth.

Microbial ecology pii:10.1007/s00248-018-1285-y [Epub ahead of print].

Xestospongia muta is among the most emblematic sponge species inhabiting coral reefs of the Caribbean Sea. Besides being the largest sponge species growing in the Caribbean, it is also known to produce secondary metabolites. This study aimed to assess the effect of depth and season on the symbiotic bacterial dynamics and major metabolite profiles of specimens of X. muta thriving in a tropical marine biome (Portobelo Bay, Panamá), which allow us to determine whether variability patterns are similar to those reported for subtropical latitudes. The bacterial assemblages were characterized using Illumina deep-sequencing and metabolomic profiles using UHPLC-DAD-ELSD from five depths (ranging 9-28 m) across two seasons (spring and autumn). Diverse symbiotic communities, representing 24 phyla with a predominance of Proteobacteria and Chloroflexi, were found. Although several thousands of OTUs were determined, most of them belong to the rare biosphere and only 23 to a core community. There was a significant difference between the structure of the microbial communities in respect to season (autumn to spring), with a further significant difference between depths only in autumn. This was partially mirrored in the metabolome profile, where the overall metabolite composition did not differ between seasons, but a significant depth gradient was observed in autumn. At the phyla level, Cyanobacteria, Firmicutes, Actinobacteria, and Spirochaete showed a mild-moderate correlation with the metabolome profile. The metabolomic profiles were mainly characterized by known brominated polyunsaturated fatty acids. This work presents findings about the composition and dynamics of the microbial assemblages of X. muta expanding and confirming current knowledge about its remarkable diversity and geographic variability as observed in this tropical marine biome.

RevDate: 2018-11-09

Rossi A, Bellone A, Fokin SI, et al (2018)

Detecting Associations Between Ciliated Protists and Prokaryotes with Culture-Independent Single-Cell Microbiomics: a Proof-of-Concept Study.

Microbial ecology pii:10.1007/s00248-018-1279-9 [Epub ahead of print].

Symbioses between prokaryotes and microbial eukaryotes, particularly ciliated protists, have been studied for a long time. Nevertheless, researchers have focused only on a few host genera and species, mainly due to difficulties in cultivating the hosts, and usually have considered a single symbiont at a time. Here, we present a pilot study using a single-cell microbiomic approach to circumvent these issues. Unicellular ciliate isolation followed by simultaneous amplification of eukaryotic and prokaryotic markers was used. Our preliminary test gave reliable and satisfactory results both on samples collected from different habitats (marine and freshwater) and on ciliates belonging to different taxonomic groups. Results suggest that, as already assessed for many macro-organisms like plants and metazoans, ciliated protists harbor distinct microbiomes. The applied approach detected new potential symbionts as well as new hosts for previously described ones, with relatively low time and cost effort and without culturing. When further developed, single-cell microbiomics for ciliates could be applied to a large number of studies aiming to unravel the evolutionary and ecological meaning of these symbiotic systems.

RevDate: 2018-11-09

Dror H, Novak L, Evans JS, et al (2018)

Core and Dynamic Microbial Communities of Two Invasive Ascidians: Can Host-Symbiont Dynamics Plasticity Affect Invasion Capacity?.

Microbial ecology pii:10.1007/s00248-018-1276-z [Epub ahead of print].

Ascidians (Chordata, Ascidiacea) are considered to be prominent marine invaders, able to tolerate highly polluted environments and fluctuations in salinity and temperature. Here, we examined the seasonal and spatial dynamics of the microbial communities in the inner-tunic of two invasive ascidians, Styela plicata (Lesueur 1823) and Herdmania momus (Savigny 1816), in order to investigate the changes that occur in the microbiome of non-indigenous ascidians in different environments. Microbial communities were characterized using next-generation sequencing of partial (V4) 16S rRNA gene sequences. A clear differentiation between the ascidian-associated microbiome and bacterioplankton was observed, and two distinct sets of operational taxonomic units (OTUs), one core and the other dynamic, were recovered from both species. The relative abundance of the dynamic OTUs in H. momus was higher than in S. plicata, for which core OTU structure was maintained independently of location. Ten and seventeen core OTUs were identified in S. plicata and H. momus, respectively, including taxa with reported capabilities of carbon fixing, ammonia oxidization, denitrification, and heavy-metal processing. The ascidian-sourced dynamic OTUs clustered in response to site and season but significantly differed from the bacterioplankton community structure. These findings suggest that the associations between invasive ascidians and their symbionts may enhance host functionality while maintaining host adaptability to changing environmental conditions.

RevDate: 2018-11-09

Liu PY, Cheng AC, Huang SW, et al (2018)

Variations in Gut Microbiota of Siberian Flying Squirrels Correspond to Seasonal Phenological Changes in Their Hokkaido Subarctic Forest Ecosystem.

Microbial ecology pii:10.1007/s00248-018-1278-x [Epub ahead of print].

Gut microbial communities of animals are influenced by diet and seasonal weather changes. Since foraging strategies of wild animals are affected by phenological changes, gut microbial communities would differ among seasons. However, interactions of plant-animal-microbiota with seasonal changes have not been well characterized. Here, we surveyed gut microbial diversity of Siberian flying squirrels (Pteromys volans orii) from a natural forest in Hokkaido during spring and summer of 2013 and 2014. Additionally, we compared microbial diversity to temperature changes and normalized difference vegetation index (NDVI). Changes in both seasonal temperature and phenology were significantly associated with alterations in gut microbiota. There were two clusters of OTUs, below and above 20 °C that were significantly correlated with low and high temperatures, respectively. Low-temperature cluster OTUs belonged to various phyla, whereas the high-temperature cluster was only constituted by Firmicutes. In conclusion, gut microbiota of Siberian flying squirrels varied with environmental changes on an ecological scale.

RevDate: 2018-11-09

Van den Abbeele P, Kamil A, Fleige L, et al (2018)

Different Oat Ingredients Stimulate Specific Microbial Metabolites in the Gut Microbiome of Three Human Individuals in Vitro.

ACS omega, 3(10):12446-12456.

We used a standardized in vitro simulation of the intestinal environment of three human donors to investigate the effect of six oat ingredients, which were produced by the application of different processing techniques, on the gut microbial community. Fructooligosaccharide was used as the positive control. Consistent changes in pH and gas production, on average -0.4 pH units and +32 kPa, indicated the high fermentability of the oat ingredients, and the resulting increased production of metabolites that are considered as beneficial for human health. These metabolites included acetate and lactate, but mostly propionate (+13.6 mM on average). All oat ingredients resulted in increased bifidobacteria levels with an average increase of 0.73 log. Moreover, a decreased production of proteolytic markers was observed, including branched short-chain fatty acids and ammonium. The results were donor-specific and product-specific. The results suggested an association between the total amounts of dietary fiber and the prebiotic potentials of different ingredients. Furthermore, as mechanical processing of oat products has previously been linked to increased extractability of dietary fibers, the obtained results suggest that different processing techniques might have impacted the potential functional properties of the final ingredients.

RevDate: 2018-11-08

Godoy-Vitorino F, Romaguera J, Zhao C, et al (2018)

Cervicovaginal Fungi and Bacteria Associated With Cervical Intraepithelial Neoplasia and High-Risk Human Papillomavirus Infections in a Hispanic Population.

Frontiers in microbiology, 9:2533.

The human cervicovaginal microbiota resides at an interface between the host and the environment and may affect susceptibility to disease. Puerto Rican women have high human papillomavirus (HPV) infection and cervical cancer rates. We hypothesized that the population structure of the cervicovaginal bacterial and fungal biota changed with cervical squamous intraepithelial lesions and HPV infections. DNA was extracted from cervix, introitus, and anal sites of 62 patients attending high-risk San Juan clinics. The 16S rRNA V4 region and ITS-2 fungal regions were amplified and sequenced using Illumina technology. HPV genotyping was determined by reverse hybridization with the HPV SPF10-LiPA25 kit. HPV prevalence was 84% of which ∼44% subjects were infected with high-risk HPV, ∼35% were co-infected with as many as 9 HPV types and ∼5% were infected with exclusively low-risk HPV types. HPV diversity did not change with cervical dysplasia. Cervical bacteria were more diverse in patients with CIN3 pre-cancerous lesions. We found enrichment of Atopobium vaginae and Gardnerella vaginalis in patients with CIN3 lesions. We found no significant bacterial biomarkers associated with HPV infections. Fungal diversity was significantly higher in cervical samples with high-risk HPV and introitus samples of patients with Atypical Squamous Cells of Undetermined Significance (ASCUS). Fungal biomarker signatures for vagina and cervix include Sporidiobolaceae and Sacharomyces for ASCUS, and Malassezia for high-risk HPV infections. Our combined data suggests that specific cervicovaginal bacterial and fungal populations are related to the host epithelial microenvironment, and could play roles in cervical dysplasia.

RevDate: 2018-11-08

Biagi E, Aceti A, Quercia S, et al (2018)

Microbial Community Dynamics in Mother's Milk and Infant's Mouth and Gut in Moderately Preterm Infants.

Frontiers in microbiology, 9:2512.

Mother's own milk represents the optimal source for preterm infant nutrition, as it promotes immune defenses and gastrointestinal function, protects against necrotizing enterocolitis, improves long-term clinical outcome and is hypothesized to drive gut microbiota assembly. Preterm infants at birth usually do not receive their mother's milk directly from the breast, because active suckling and coordination between suckling, swallowing and breathing do not develop until 32-34 weeks gestational age, but actual breastfeeding is usually possible as they grow older. Here, we enrolled moderately preterm infants (gestational age 32-34 weeks) to longitudinally characterize mothers' milk and infants' gut and oral microbiomes, up to more than 200 days after birth, through 16S rRNA sequencing. This peculiar population offers the chance to disentangle the differential contribution of human milk feeding per se vs. actual breastfeeding in the development of infant microbiomes, that have both been acknowledged as crucial contributors to short and long-term infant health status. In this cohort, the milk microbiome composition seemed to change following the infant's latching to the mother's breast, shifting toward a more diverse microbial community dominated by typical oral microbes, i.e., Streptococcus and Rothia. Even if all infants in the present study were fed human milk, features typical of healthy, full term, exclusively breastfed infants, i.e., high percentages of Bifidobacterium and low abundances of Pseudomonas in fecal and oral samples, respectively, were detected in samples taken after actual breastfeeding started. These findings underline the importance of encouraging not only human milk feeding, but also an early start of actual breastfeeding in preterm infants, since the infant's latching to the mother's breast might constitute an independent factor helping the health-promoting assembly of the infant gut microbiome.

RevDate: 2018-11-08

Mehner-Breitfeld D, Rathmann C, Riedel T, et al (2018)

Evidence for an Adaptation of a Phage-Derived Holin/Endolysin System to Toxin Transport in Clostridioides difficile.

Frontiers in microbiology, 9:2446.

The pathogenicity locus (PaLoc) of Clostridioides difficile usually comprises five genes (tcdR, tcdB, tcdE, tcdA, tcdC). While the proteins TcdA and TcdB represent the main toxins of this pathogen, TcdR and TcdC are involved in the regulation of their production. TcdE is a holin family protein, members of which are usually involved in the transport of cell wall-degrading enzymes (endolysins) for phage-induced lysis. In the past, TcdE has been shown to contribute to the release of TcdA and TcdB, but it is unclear whether it mediates a specific transport or rather a lysis of cells. TcdE of C. difficile strains analyzed so far can be produced in three isoforms that are initiated from distinct N-terminal ATG codons. When produced in Escherichia coli, we found that the longest TcdE isoform had a moderate effect on cell growth, whereas the shortest isoform strongly induced lysis. The effect of the longest isoform was inhibitory for cell lysis, implying a regulatory function of the N-terminal 24 residues. We analyzed the PaLoc sequence of 44 C. difficile isolates and found that four of these apparently encode only the short TcdE isoforms, and the most closely related holins from C. difficile phages only possess one of these initiation codons, indicating that an N-terminal extension of TcdE evolved in C. difficile. All PaLoc sequences comprised also a conserved gene encoding a short fragment of an endolysin remnant of a phage holin/endolysin pair. We could produce this peptide, which we named TcdL, and demonstrated by bacterial two-hybrid analysis a self-interaction and an interaction with TcdB that might serve to mediate TcdE-dependent transport.

RevDate: 2018-11-08

Wankhade UD, Zhong Y, Kang P, et al (2018)

Maternal High-Fat Diet Programs Offspring Liver Steatosis in a Sexually Dimorphic Manner in Association with Changes in Gut Microbial Ecology in Mice.

Scientific reports, 8(1):16502 pii:10.1038/s41598-018-34453-0.

The contributions of maternal diet and obesity in shaping offspring microbiome remain unclear. Here we employed a mouse model of maternal diet-induced obesity via high-fat diet feeding (HFD, 45% fat calories) for 12 wk prior to conception on offspring gut microbial ecology. Male and female offspring were provided access to control or HFD from weaning until 17 wk of age. Maternal HFD-associated programming was sexually dimorphic, with male offspring from HFD dams showing hyper-responsive weight gain to postnatal HFD. Likewise, microbiome analysis of offspring cecal contents showed differences in α-diversity, β-diversity and higher Firmicutes in male compared to female mice. Weight gain in offspring was significantly associated with abundance of Lachnospiraceae and Clostridiaceae families and Adlercreutzia, Coprococcus and Lactococcus genera. Sex differences in metagenomic pathways relating to lipid metabolism, bile acid biosynthesis and immune response were also observed. HFD-fed male offspring from HFD dams also showed worse hepatic pathology, increased pro-inflammatory cytokines, altered expression of bile acid regulators (Cyp7a1, Cyp8b1 and Cyp39a1) and serum bile acid concentrations. These findings suggest that maternal HFD alters gut microbiota composition and weight gain of offspring in a sexually dimorphic manner, coincident with fatty liver and a pro-inflammatory state in male offspring.

RevDate: 2018-11-07

Veresoglou SD, Verbruggen E, Makarova O, et al (2018)

Arbuscular Mycorrhizal Fungi Alter the Community Structure of Ammonia Oxidizers at High Fertility via Competition for Soil NH4.

Microbial ecology pii:10.1007/s00248-018-1281-2 [Epub ahead of print].

Nitrification represents a central process in the cycling of nitrogen (N) which in high-fertility habitats can occasionally be undesirable. Here, we explore how arbuscular mycorrhiza (AM) impacts nitrification when N availability is not limiting to plant growth. We wanted to test which of the mechanisms that have been proposed in the literature best describes how AM influences nitrification. We manipulated the growth settings of Plantago lanceolata so that we could control the mycorrhizal state of our plants. AM induced no changes in the potential nitrification rates or the estimates of ammonium oxidizing (AO) bacteria. However, we could observe a moderate shift in the community of ammonia-oxidizers, which matched the shift we saw when comparing hyphosphere to rhizosphere soil samples and mirrored well changes in the availability of ammonium in soil. We interpret our results as support that it is competition for N that drives the interaction between AM and AO. Our experiment sheds light on an understudied interaction which is pertinent to typical management practices in agricultural systems.

RevDate: 2018-11-06

Kraus C, Voegele RT, M Fischer (2018)

Temporal Development of the Culturable, Endophytic Fungal Community in Healthy Grapevine Branches and Occurrence of GTD-Associated Fungi.

Microbial ecology pii:10.1007/s00248-018-1280-3 [Epub ahead of print].

Endophytic fungi play an important role in the life of grapevine, either as beneficial microorganisms or as pathogens. Many surveys concerning the fungal grapevine community have been conducted. Nevertheless, exactly how the fungal community arises within the plant and develops from young shoots to mature vines is still unknown. Therefore, it was the aim of this study to investigate the early development of endophytic fungal communities in healthy grapevine branches from 2 months to 8 years old. More than 3800 fungi belonging to 86 operational taxonomic units (OTUs) were isolated from wood samples and assigned to eight age groups. The community composition within the age groups changed and significant differences between young (≤ 1 year) and old (> 1 year) branches were found. The former were primarily dominated by ubiquitous, fast-growing fungi like Alternaria spp., Aureobasidium pullulans, Cladosporium spp., or Epicoccum nigrum, while communities of perennial branches additionally harbored many grapevine trunk disease (GTD)-associated fungi such as Diplodia seriata or Eutypa lata. This work gives an insight into the early development of fungal communities in grapevine, the nature and composition of primary settlers and core communities, as well as the emergence of GTD-associated fungi in perennial wood. This information may help grapevine growers to better estimate the risk in relation to the applied training system, producing mainly old branches or young shoots.

RevDate: 2018-11-06

Palacios OA, Lopez BR, Bashan Y, et al (2018)

Early Changes in Nutritional Conditions Affect Formation of Synthetic Mutualism Between Chlorella sorokiniana and the Bacterium Azospirillum brasilense.

Microbial ecology pii:10.1007/s00248-018-1282-1 [Epub ahead of print].

The effect of three different nutritional conditions during the initial 12 h of interaction between the microalgae Chlorella sorokiniana UTEX 2714 and the plant growth-promoting bacterium Azospirillum brasilense Cd on formation of synthetic mutualism was assessed by changes in population growth, production of signal molecules tryptophan and indole-3-acetic acid, starch accumulation, and patterns of cell aggregation. When the interaction was supported by a nutrient-rich medium, production of both signal molecules was detected, but not when this interaction began with nitrogen-free (N-free) or carbon-free (C-free) media. Overall, populations of bacteria and microalgae were larger when co-immobilized. However, the highest starch production was measured in C. sorokiniana immobilized alone and growing continuously in a C-free mineral medium. In this interaction, the initial nutritional condition influenced the time at which the highest accumulation of starch occurred in Chlorella, where the N-free medium induced faster starch production and the richer medium delayed its accumulation. Formation of aggregates made of microalgae and bacteria occurred in all nutritional conditions, with maximum at 83 h in mineral medium, and coincided with declining starch content. This study demonstrates that synthetic mutualism between C. sorokiniana and A. brasilense can be modulated by the initial nutritional condition, mainly by the presence or absence of nitrogen and carbon in the medium in which they are interacting.

RevDate: 2018-11-06

Lau NS, Zarkasi KZ, Md Sah ASR, et al (2018)

Diversity and Coding Potential of the Microbiota in the Photic and Aphotic Zones of Tropical Man-Made Lake with Intensive Aquaculture Activities: a Case Study on Temengor Lake, Malaysia.

Microbial ecology pii:10.1007/s00248-018-1283-0 [Epub ahead of print].

Although freshwater biomes cover less than 1% of the Earth's surface, they have disproportionate ecological significances. Attempts to study the taxonomy and function of freshwater microbiota are currently limited to samples collected from temperate lakes. In this study, we investigated samples from the photic and aphotic of an aquaculture site (disturbed) of Temengor Lake, a tropical lake in comparison with the undisturbed site of the lake using 16S rRNA amplicon and shotgun metagenomic approaches. Vertical changes in bacterial community composition and function of the Temengor Lake metagenomes were observed. The photic water layer of Temengor Lake was dominated by typical freshwater assemblages consisting of Proteobacteria, Actinobacteria, Bacteroidetes, Verrucomicrobia, and Cyanobacteria lineages. On the other hand, the aphotic water featured in addition to Proteobacteria, Bacteroidetes, Verrucomicrobia, and two more abundant bacterial phyla that are typically ubiquitous in anoxic habitats (Chloroflexi and Firmicutes). The aphotic zone of Temengor Lake exhibited genetic potential for nitrogen and sulfur metabolisms for which terminal electron acceptors other than oxygen are used in the reactions. The aphotic water of the disturbed site also showed an overrepresentation of genes associated with the metabolism of carbohydrates, likely driven by the enrichment of nutrient resulting from aquaculture activities at the site. The results presented in this study can serve as a basis for understanding the structure and functional capacity of the microbial communities in the photic and aphotic zones/water layers of tropical man-made lakes.

RevDate: 2018-11-06

Md Zoqratt MZH, Eng WWH, Thai BT, et al (2018)

Microbiome analysis of Pacific white shrimp gut and rearing water from Malaysia and Vietnam: implications for aquaculture research and management.

PeerJ, 6:e5826 pii:5826.

Aquaculture production of the Pacific white shrimp is the largest in the world for crustacean species. Crucial to the sustainable global production of this important seafood species is a fundamental understanding of the shrimp gut microbiota and its relationship to the microbial ecology of shrimp pond. This is especially true, given the recently recognized role of beneficial microbes in promoting shrimp nutrient intake and in conferring resistance against pathogens. Unfortunately, aquaculture-related microbiome studies are scarce in Southeast Asia countries despite the severe impact of early mortality syndrome outbreaks on shrimp production in the region. In this study, we employed the 16S rRNA amplicon (V3-V4 region) sequencing and amplicon sequence variants (ASV) method to investigate the microbial diversity of shrimp guts and pond water samples collected from aquaculture farms located in Malaysia and Vietnam. Substantial differences in the pond microbiota were observed between countries with the presence and absence of several taxa extending to the family level. Microbial diversity of the shrimp gut was found to be generally lower than that of the pond environments with a few ubiquitous genera representing a majority of the shrimp gut microbial diversity such as Vibrio and Photobacterium, indicating host-specific selection of microbial species. Given the high sequence conservation of the 16S rRNA gene, we assessed its veracity at distinguishing Vibrio species based on nucleotide alignment against type strain reference sequences and demonstrated the utility of ASV approach in uncovering a wider diversity of Vibrio species compared to the conventional OTU clustering approach.

RevDate: 2018-11-06

Cabernard L, Roscher L, Lorenz C, et al (2018)

Comparison of Raman and Fourier Transform Infrared Spectroscopy for the Quantification of Microplastics in the Aquatic Environment.

Environmental science & technology [Epub ahead of print].

Microplastics (MPs, <5 mm) have been reported as emerging environmental contaminants, but reliable data are still lacking. We compared the two most promising techniques for MP analysis, namely, Raman and Fourier transform infrared (FTIR) spectroscopy, by analyzing MPs extracted from North Sea surface waters. Microplastics >500 μm were visually sorted and manually analyzed by μ-Raman and attenuated total reflection (ATR)-FTIR spectroscopy. Microplastics ≤500 μm were concentrated on gold-coated filters and analyzed by automated single-particle exploration coupled to μ-Raman (ASPEx-μ-Raman) and FTIR imaging (reflection mode). The number of identified MPs >500 μm was slightly higher for μ-Raman (+23%) than ATR-FTIR analysis. Concerning MPs ≤500 μm, ASPEx-μ-Raman quantified two-times higher MP numbers but required a four-times higher analysis time compared to FTIR imaging. Because ASPEx-μ-Raman revealed far higher MP concentrations (38-2621 particles m-3) compared to the results of previous water studies (0-559 particles m-3), the environmental concentration of MPs ≤500 μm may have been underestimated until now. This may be attributed to the exceptional increase in concentration with decreasing MP size found in this work. Our results demonstrate the need for further research to enable time-efficient routine application of ASPEx-μ-Raman for reliable MP counting down to 1 μm.

RevDate: 2018-11-04

van der Waals MJ, Plugge C, Meima-Franke M, et al (2018)

Ethyl tert-butyl ether (EtBE) degradation by an algal-bacterial culture obtained from contaminated groundwater.

Water research, 148:314-323 pii:S0043-1354(18)30847-9 [Epub ahead of print].

EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces the fossil-based MtBE. Biodegradation of EtBE to harmless metabolites or end products can reduce the environmental and human health risks after accidental release. In this study, an algal-bacterial culture enriched from contaminated groundwater was used to (i) assess the potential for EtBE degradation, (ii) resolve the EtBE degradation pathway and (iii) characterize the phylogenetic composition of the bacterial community involved in EtBE degradation in contaminated groundwater. In an unamended microcosm, algal growth was observed after eight weeks when exposed to a day-night light cycle. In the fed-batch reactor, oxygen produced by the algae Scenedesmus and Chlorella was used by bacteria to degrade 50 μM EtBE replenishments with a cumulative total of 1250 μM in a day/night cycle (650 lux), over a period of 913 days. The microbial community in the fed-batch reactor degraded EtBE, using a P450 monooxygenase and 2-hydroxyisobutyryl-CoA mutase, to tert-butyl alcohol (TBA), ethanol and CO2 as determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) with 13C6 labeled EtBE in a fed-batch vessel showed no significant difference in community profiles of the 13C and 12C enriched DNA fractions, with representatives of the families Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This is the first study describing micro-oxic degradation of EtBE by an algal-bacterial culture. This algal-bacterial culture has advantages compared with conventional aerobic treatments: (i) a lower risk of EtBE evaporation and (ii) no need for external oxygen supply in the presence of light. This study provides novel leads towards future possibilities to implement algal-bacterial consortia in field-scale groundwater or wastewater treatment.

RevDate: 2018-11-05

Gómez-Sagasti MT, Epelde L, Anza M, et al (2018)

The impact of nanoscale zero-valent iron particles on soil microbial communities is soil dependent.

Journal of hazardous materials, 364:591-599 pii:S0304-3894(18)30943-9 [Epub ahead of print].

The application of nanoscale zero-valent iron particles (nZVI) for the remediation of contaminated sites is very promising. However, information concerning the ecotoxicity of nZVI on soil microbial communities and, hence, soil quality, is still scarce. We carried out a three-month experiment to evaluate the impact of the application of different concentrations of nZVI (from 1 to 20 mg g DW soil-1) on soil microbial properties in a clay-loam versus a sandy-loam soil. Data on microbial biomass (total bacteria and fungi by qPCR, microbial biomass carbon), activity (β-glucosidase, arylsulphatase and urease activities), and functional (Biolog Ecoplates™) and structural (ARISA, 16S rRNA amplicon sequencing) diversity evidenced that the sandy-loam soil was more vulnerable to the presence of nZVI than the clay-loam soil. In the sandy-loam soil, arylsulphatase activity and bacterial abundance, richness and diversity were susceptible to the presence of nZVI. The high content of clay and organic matter present in the clay-loam soil may explain the observed negligible effects of nZVI on soil microbial properties. It was concluded that the impact of nZVI on soil microbial communities and, hence, soil quality, is soil dependent.

RevDate: 2018-11-02

Zhang Y, Hua ZS, Lu H, et al (2018)

Elucidating functional microorganisms and metabolic mechanisms in a novel engineered ecosystem integrating C, N, P and S biotransformation by metagenomics.

Water research, 148:219-230 pii:S0043-1354(18)30858-3 [Epub ahead of print].

Denitrifying sulfur conversion-associated enhanced biological phosphorous removal (DS-EBPR) system is not only a novel wastewater treatment process, but also an ideal model for microbial ecology in a community context. However, it exists the knowledge gap on the roles and interactions of functional microorganisms in the DS-EBPR system for carbon (C), nitrogen (N), phosphorus (P) and sulfur (S) bioconversions. We use genome-resolved metagenomics to build up an ecological model of microbial communities in a lab-scale DS-EBPR system with stable operation for more than 400 days. Our results yield 11 near-complete draft genomes that represent a substantial portion of the microbial community (39.4%). Sulfate-reducing bacteria (SRB) and sulfide-oxidizing bacteria (SOB) promote complex metabolic processes and interactions for C, N, P and S conversions. Bins 1-4 and 10 are considered as new potential polyphosphate-accumulating organisms (PAOs), in which Bins 1-4 can be considered as S-related PAOs (S-PAOs) with no previously cultivated or reported members. Our findings give an insight into a new ecological system with C, N, P and S simultaneous bioconversions and improve the understanding of interactions among SRB, SOB, denitrifiers and PAOs within a community context.

RevDate: 2018-11-02

de Nijs EA, Hicks LC, Leizeaga A, et al (2018)

Soil microbial moisture dependences and responses to drying-rewetting: the legacy of 18 years drought.

Global change biology [Epub ahead of print].

Climate change will alter precipitation patterns with consequences for soil C cycling. An understanding of how fluctuating soil moisture affects microbial processes is therefore critical to predict responses to future global change. We investigated how long-term experimental field drought influences microbial tolerance to lower moisture levels ('resistance') and ability to recover when rewetted after drought ('resilience'), using soils from a heathland which had been subjected to experimental precipitation reduction during the summer for 18 years. We tested whether drought could induce increased resistance, resilience, and changes in the balance between respiration and bacterial growth during perturbation events, by following a two-tiered approach. We first evaluated the effects of the long-term summer drought on microbial community functioning to drought and drying-rewetting (D/RW), and second tested the ability to alter resistance and resilience through additional perturbation cycles. A history of summer drought in the field selected for increased resilience but not resistance, suggesting that rewetting after drought, rather than low moisture levels during drought, was the selective pressure shaping the microbial community functions. Laboratory D/RW cycles also selected for communities with a higher resilience rather than increased resistance. The ratio of respiration to bacterial growth during D/RW perturbation was lower for the field drought-exposed communities and decreased for both field-treatments during the D/RW cycles. This suggests that cycles of D/RW also structure microbial communities to respond quickly and efficiently to rewetting after drought. Our findings imply that microbial communities can adapt to changing climatic conditions and that this might slow the rate of SOC loss predicted to be induced by future cyclic drought. This article is protected by copyright. All rights reserved.

RevDate: 2018-11-02

Florez AM, Suarez-Barrera MO, Morales GM, et al (2018)

Toxic Activity, Molecular Modeling and Docking Simulations of Bacillus thuringiensis Cry11 Toxin Variants Obtained via DNA Shuffling.

Frontiers in microbiology, 9:2461.

The Cry11 family belongs to a large group of δ-endotoxins that share three distinct structural domains. Among the dipteran-active toxins referred to as three-domain Cry11 toxins, the Cry11Aa protein from Bacillus thuringiensis subsp. israelensis (Bti) has been the most extensively studied. Despite the potential of Bti as an effective biological control agent, the understanding of Cry11 toxins remains incomplete. In this study, five Cry11 variants obtained via DNA shuffling displayed toxic activity against Aedes aegypti and Culex quinquefasciatus. Three of these Cry11 variants (8, 23, and 79) were characterized via 3D modeling and analysis of docking with ALP1. The relevant mutations in these variants, such as deletions, insertions and point mutations, are discussed in relation to their structural domains, toxic activities and toxin-receptor interactions. Importantly, deletion of the N-terminal segment in domain I was not associated with any change in toxic activity, and domain III exhibited higher sequence variability than domains I and II. Variant 8 exhibited up to 3.78- and 6.09-fold higher toxicity to A. aegypti than Cry11Bb and Cry11Aa, respectively. Importantly, variant 79 showed an α-helix conformation at the C-terminus and formed crystals retaining toxic activity. These findings indicate that five Cry11 variants were preferentially reassembled from the cry11Aa gene during DNA shuffling. The mutations described in loop 2 and loop 3 of domain II provide valuable information regarding the activity of Cry11 toxins against A. aegypti and C. quinquefasciatus larvae and reveal new insights into the application of directed evolution strategies to study the genetic variability of specific domains in cry11 family genes.

RevDate: 2018-11-02

Ihekweazu FD, J Versalovic (2018)

Development of the Pediatric Gut Microbiome: Impact on Health and Disease.

The American journal of the medical sciences, 356(5):413-423.

The intestinal microbiota are important in human growth and development. Microbial composition may yield insights into the temporal development of microbial communities and vulnerabilities to disorders of microbial ecology such as recurrent Clostridium difficile infection. Discoveries of key microbiome features of carbohydrate and amino acid metabolism are lending new insights into possible therapies or preventative strategies for inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). In this review, we summarize the current understanding of the development of the pediatric gastrointestinal microbiome, the influence of the microbiome on the developing brain through the gut-brain axis, and the impact of dysbiosis on disease development. Dysbiosis is explored in the context of pediatric allergy and asthma, recurrent C. difficile infection, IBD, IBS, and metabolic disorders. The central premise is that the human intestinal microbiome plays a vital role in health and disease, beginning in the prenatal period and extending throughout childhood.

RevDate: 2018-10-31

Van Hecke T, De Vrieze J, Boon N, et al (2018)

Combined Consumption of Beef-Based Cooked Mince and Sucrose Stimulates Oxidative Stress, Cardiac Hypertrophy, and Colonic Outgrowth of Desulfovibrionaceae in Rats.

Molecular nutrition & food research [Epub ahead of print].

SCOPE: High consumption of red meat and sucrose increases the epidemiological risk for chronic diseases. Mechanistic hypotheses include alterations in oxidative status, gut microbial composition, fat deposition and low-grade inflammation.

METHODS AND RESULTS: For two weeks, 40 rats consumed a diet high in white or red meat (chicken-based or beef-based cooked mince respectively), and containing corn starch or sucrose in a 2 × 2 factorial design. Lard was mixed with lean chicken or beef to obtain comparable dietary fatty acid profiles. Beef (vs. chicken)-fed rats had higher lipid oxidation products (malondialdehyde, 4-hydroxy-2-nonenal and hexanal) in stomach content and blood, and lower blood glutathione. Sucrose (vs. corn starch)-fed rats showed increased blood lipid oxidation products and glutathione peroxidase activity, higher liver weight and malondialdehyde concentrations, and mesenterial and retroperitoneal fat accumulation. Beef-sucrose-fed rats had increased cardiac weight, suggesting pathophysiological effects on the cardiovascular system. The colonic microbiome of beef-sucrose-fed rats showed an outgrowth of the sulfate-reducing family of the Desulfovibrionaceae, partly in expense of the Lactobacillus genus, indicating intestinal dysbiosis. Blood C-reactive protein, a marker for inflammation, was not different among groups.

CONCLUSIONS: Consumption of a cooked beef-based meat product with sucrose increased oxidative stress parameters and promoted cardiac hypertrophy and intestinal dysbiosis. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-31

Hale VL, Jeraldo P, Chen J, et al (2018)

Distinct microbes, metabolites, and ecologies define the microbiome in deficient and proficient mismatch repair colorectal cancers.

Genome medicine, 10(1):78 pii:10.1186/s13073-018-0586-6.

BACKGROUND: Links between colorectal cancer (CRC) and the gut microbiome have been established, but the specific microbial species and their role in carcinogenesis remain an active area of inquiry. Our understanding would be enhanced by better accounting for tumor subtype, microbial community interactions, metabolism, and ecology.

METHODS: We collected paired colon tumor and normal-adjacent tissue and mucosa samples from 83 individuals who underwent partial or total colectomies for CRC. Mismatch repair (MMR) status was determined in each tumor sample and classified as either deficient MMR (dMMR) or proficient MMR (pMMR) tumor subtypes. Samples underwent 16S rRNA gene sequencing and a subset of samples from 50 individuals were submitted for targeted metabolomic analysis to quantify amino acids and short-chain fatty acids. A PERMANOVA was used to identify the biological variables that explained variance within the microbial communities. dMMR and pMMR microbial communities were then analyzed separately using a generalized linear mixed effects model that accounted for MMR status, sample location, intra-subject variability, and read depth. Genome-scale metabolic models were then used to generate microbial interaction networks for dMMR and pMMR microbial communities. We assessed global network properties as well as the metabolic influence of each microbe within the dMMR and pMMR networks.

RESULTS: We demonstrate distinct roles for microbes in dMMR and pMMR CRC. Bacteroides fragilis and sulfidogenic Fusobacterium nucleatum were significantly enriched in dMMR CRC, but not pMMR CRC. These findings were further supported by metabolic modeling and metabolomics indicating suppression of B. fragilis in pMMR CRC and increased production of amino acid proxies for hydrogen sulfide in dMMR CRC.

CONCLUSIONS: Integrating tumor biology and microbial ecology highlighted distinct microbial, metabolic, and ecological properties unique to dMMR and pMMR CRC. This approach could critically improve our ability to define, predict, prevent, and treat colorectal cancers.

RevDate: 2018-10-30

Philip N, L Walsh (2018)

The potential ecological effects of Casein Phosphopeptide-Amorphous Calcium Phosphate in dental caries prevention.

Australian dental journal [Epub ahead of print].

Contemporary caries prevention protocols recommend not only effective remineralizing agents but also ecological measures to reverse the dental plaque dysbiosis responsible for the disease pathogenesis. There is a high-level of evidence supporting the remineralizing efficacy of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) from studies around the world. There is now emerging evidence that CPP-ACP may also have a beneficial influence on the dental plaque microbial ecology and homeostasis. The ecological cariostatic effects of CPP-ACP are believed to be mediated predominantly through its anti-adhesion, buffering, and biofilm disrupting actions. This review principally discusses the ecological mechanisms of CPP-ACP and presents the current evidence for its effects on the oral microbiome ecology. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-30

Reese AT, Pereira FC, Schintlmeister A, et al (2018)

Microbial nitrogen limitation in the mammalian large intestine.

Nature microbiology pii:10.1038/s41564-018-0267-7 [Epub ahead of print].

Resource limitation is a fundamental factor governing the composition and function of ecological communities. However, the role of resource supply in structuring the intestinal microbiome has not been established and represents a challenge for mammals that rely on microbial symbionts for digestion: too little supply might starve the microbiome while too much might starve the host. We present evidence that microbiota occupy a habitat that is limited in total nitrogen supply within the large intestines of 30 mammal species. Lowering dietary protein levels in mice reduced their faecal concentrations of bacteria. A gradient of stoichiometry along the length of the gut was consistent with the hypothesis that intestinal nitrogen limitation results from host absorption of dietary nutrients. Nitrogen availability is also likely to be shaped by host-microbe interactions: levels of host-secreted nitrogen were altered in germ-free mice and when bacterial loads were reduced via experimental antibiotic treatment. Single-cell spectrometry revealed that members of the phylum Bacteroidetes consumed nitrogen in the large intestine more readily than other commensal taxa did. Our findings support a model where nitrogen limitation arises from preferential host use of dietary nutrients. We speculate that this resource limitation could enable hosts to regulate microbial communities in the large intestine. Commensal microbiota may have adapted to nitrogen-limited settings, suggesting one reason why excess dietary protein has been associated with degraded gut-microbial ecosystems.

RevDate: 2018-10-29

Nottingham AT, Bååth E, Reischke S, et al (2018)

Adaptation of soil microbial growth to temperature: using a tropical elevation gradient to predict future changes.

Global change biology [Epub ahead of print].

Terrestrial biogeochemical feedbacks to the climate are strongly modulated by the temperature response of soil microorganisms. Tropical forests, in particular, exert a major influence on global climate because they are the most productive terrestrial ecosystem. We used an elevation gradient across tropical forest in the Andes (a gradient of 20°C mean annual temperature, MAT), to test whether soil bacterial and fungal community growth responses are adapted to long-term temperature differences. We evaluated the temperature dependency of soil bacterial and fungal growth using the leucine- and acetate-incorporation methods, respectively, and determined indices for the temperature response of growth: Q10 and Tmin (the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q10 and Tmin of growth. Across a MAT range from 6°C to 26°C, the Q10 and Tmin varied for bacterial growth (Q10-20 = 2.4 to 3.5; Tmin = -8°C to -1.5°C) and fungal growth (Q10-20 = 2.6 to 3.6; Tmin = -6°C to -1°C). Thus, bacteria and fungi did not differ in their growth temperature responses with changes in MAT. Our findings indicate that across natural temperature gradients, each increase in MAT by 1°C results in increases in Tmin of microbial growth by approximately 0.3°C and Q10-20 by 0.05, consistent with long-term temperature adaptation of soil microbial communities. A 2°C warming would increase microbial activity across a MAT gradient of 6°C to 26°C by 28% to 15%, respectively, and temperature adaptation of microbial communities would further increase activity by 1.2% to 0.3%. The impact of warming on microbial activity, and the related impact on soil carbon cycling, is thus greater in regions with lower MAT. These results can be used to predict future changes in the temperature response of microbial activity over different levels of warming and over large temperature ranges, extending to tropical regions. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-29

Cooper R, Tsimring L, J Hasty (2018)

Microfluidics-Based Analysis of Contact-dependent Bacterial Interactions.

Bio-protocol, 8(16):.

Bacteria in nature live in complex communities with multiple cell types and spatially-dependent interactions. Studying cells in well-mixed environments such as shaking culture tubes or flasks cannot capture these spatial dynamics, but cells growing in full-fledged biofilms are difficult to observe in real time. We present here a protocol for observing time-resolved, multi-species interactions at single-cell resolution. The protocol involves growing bacterial cells in a near monolayer in a microfluidic device. As a demonstration, we describe in particular observing the dynamic interactions between E. coli and Acinetobacter baylyi. In this case, the protocol is capable of observing both contact-dependent lysis of E. coli by A. baylyi via the Type VI Secretion System (T6SS) and subsequent functional horizontal gene transfer (HGT) of genes from E. coli to A. baylyi.

RevDate: 2018-10-29

Braga RM, Padilla G, WL Araújo (2018)

The biotechnological potential of Epicoccum spp.: diversity of secondary metabolites.

Critical reviews in microbiology [Epub ahead of print].

Epicoccum is a genus of ubiquitous fungi typically found in air, in soil, and on decaying vegetation. They also commonly display an endophytic lifestyle and are isolated from diverse plant tissues. The fungi from the genus Epicoccum are mainly known for their use as biocontrol agents against phytopathogens and for their ability to produce many secondary metabolites with potential biotechnological applications, such as antioxidant, anticancer,r and antimicrobial compounds. Among the bioactive compounds produced by Epicoccum spp., epicocconone is a commercially available fluorophore, D8646-2-6 is a patented telomerase inhibitor, and taxol is an anticancer drug originally isolated from Taxus brevifolia. Epicoccum spp. also produces epicolactone, an antimicrobial compound with a unique and complex structure that has aroused considerable interest in the chemical-synthesis community. The main goal of the present review is to discuss the diversity of secondary metabolites produced by Epicoccum spp., their biotechnological applications, and proposed hypothetical biosynthesis. In addition, the use of Epicoccum spp. as biocontrol agents and the pigments produced by these fungi are also discussed.

RevDate: 2018-10-28

Feng Y, Chen R, Stegen JC, et al (2018)

Two key features influencing community assembly processes at regional scale: Initial state and degree of change in environmental conditions.

Molecular ecology [Epub ahead of print].

Belowground microbial communities strongly influence ecosystem function such that predicting function may rely on understanding ecological processes that assemble communities. Uncertainty remains, however, in what governs the relative contributions of different ecological processes. To help fill this knowledge gap we test the general hypothesis that both initial state and degree of change in environmental conditions govern the relative contributions of different ecological assembly processes. To do so we leveraged regional-scale nutrient and organic matter addition experiments and used soil organic matter (SOM) as a proxy of integrated soil environmental conditions. Consistent with our hypothesis, we found that both the initial amount of SOM and the degree of change in SOM-in response to nutrient addition-influenced the relative contributions of different ecological assembly processes. These influences were most clearly observed at the regional scale, suggesting potential scale dependence. More specifically, nutrient additions homogenized bacterial community composition due to enhanced influences of homogenizing dispersal when SOM content was initially high. In contrast, nutrient additions led to divergence in community composition due to variable selection when initial SOM was low and/or when SOM increased significantly in response to nutrient additions. Our findings indicate important connections among initial conditions, degree of change in environmental variables, and microbial community assembly processes that may influence ecosystem processes. These conceptual inferences highlight a need to strengthen connections between ecological theory and biogeochemical modeling. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-28

Li X, Jousset A, de Boer W, et al (2018)

Legacy of land use history determines reprogramming of plant physiology by soil microbiome.

The ISME journal pii:10.1038/s41396-018-0300-0 [Epub ahead of print].

Microorganisms associated with roots are thought to be part of the so-called extended plant phenotypes with roles in the acquisition of nutrients, production of growth hormones, and defense against diseases. Since the crops selectively enrich most rhizosphere microbes out of the bulk soil, we hypothesized that changes in the composition of bulk soil communities caused by agricultural management affect the extended plant phenotype. In the current study, we performed shotgun metagenome sequencing of the rhizosphere microbiome of the peanut (Arachis hypogaea) and metatranscriptome analysis of the roots of peanut plants grown in the soil with different management histories, peanut monocropping and crop rotation. We found that the past planting record had a significant effect on the assembly of the microbial community in the peanut rhizosphere, indicating a soil memory effect. Monocropping resulted in a reduction of the rhizosphere microbial diversity, an enrichment of several rare species, and a reduced representation of traits related to plant performance, such as nutrients metabolism and phytohormone biosynthesis. Furthermore, peanut plants in monocropped soil exhibited a significant reduction in growth coinciding with a down-regulation of genes related to hormone production, mainly auxin and cytokinin, and up-regulation of genes related to the abscisic acid, salicylic acid, jasmonic acid, and ethylene pathways. These findings suggest that land use history affects crop rhizosphere microbiomes and plant physiology.

RevDate: 2018-10-27

Lian Y, Yang J, Lian Y, et al (2018)

DUXAP8, a pseudogene derived lncRNA, promotes growth of pancreatic carcinoma cells by epigenetically silencing CDKN1A and KLF2.

Cancer communications (London, England), 38(1):64 pii:10.1186/s40880-018-0333-9.

BACKGROUND: Recent studies highlight pseudogene derived long non-coding RNAs (lncRNAs) as key regulators of cancer biology. However, few of them have been well characterized in pancreatic cancer. Here, we aimed to identify the association between pseudogene derived lncRNA DUXAP8 and growth of pancreatic cancer cells.

METHODS: We screened for pseudogene derived lncRNAs associated with human pancreatic cancer by comparative analysis of three independent datasets from GEO. Quantitative real-time reverse transcription polymerase chain reaction was used to assess the relative expression of DUXAP8 in pancreatic cancer tissues and cells. Loss-of-function approaches were used to investigate the potential functional roles of DUXAP8 in pancreatic cancer cell proliferation and apoptosis in vitro and in vivo. RNA immunoprecipitation, chromosome immunoprecipitation assay and rescue experiments were performed to analyze the association of DUXAP8 with target proteins and genes in pancreatic cancer cells.

RESULTS: Pancreatic cancer tissues had significantly higher DUXAP8 levels than paired adjacent normal tissues. High DUXAP8 expression was associated with a larger tumor size, advanced pathological stage and shorter overall survival of pancreatic cancer patients. Moreover, silencing DUXAP8 expression by siRNA or shRNA inhibited pancreatic cancer cell proliferation and promoted apoptosis in vitro and in vivo. Mechanistic analyses indicated that DUXAP8 regulates PC cell proliferation partly through downregulation of tumor suppressor CDKN1A and KLF2 expression.

CONCLUSION: Our results suggest that tumor expression of pseudogene derived lncRNA DUXAP8 plays an important role in pancreatic cancer progression. DUXAP8 may serve as a candidate biomarker and represent a novel therapeutic target of pancreatic cancer.

RevDate: 2018-10-27

Ren L, Song X, He D, et al (2018)

Bacterioplankton metacommunity processes across thermal gradients: weaker species sorting but stronger niche segregation in summer than in winter subtropical bay.

Applied and environmental microbiology pii:AEM.02088-18 [Epub ahead of print].

Thermal effluents from nuclear power plants greatly change the environmental and ecological conditions of the receiving marine water body, but knowledge about their impact on microbial ecology is limited. Here, we used high-throughput sequencing of 16S rRNA gene to examine marine bacterioplankton metacommunity assembly across thermal gradients in two representative seasons (i.e., winter and summer) in subtropical bay locating on the northern coast of the South China Sea. We found high heterogeneity in bacterioplankton community compositions (BCCs) across thermal gradients and between seasons. The spatially structured temperature gradient created by thermal effluents was the key determinant of BCC, but its influence differed by season. Using a metacommunity approach, we found that in the thermal discharge area, i.e., where water frequently exchanges with surrounding seawater and thermal effluent water, the BCC spatial patterns were shaped by species sorting rather than mass effects from surrounding seawater or dilution of thermal effluent water by surrounding seawater. However, this effect of species sorting was weaker in summer than in winter seawater. In both seasons, bacterioplankton community structure was predominately determined by niche sharing; however, the relative importance of niche segregation was enhanced in summer seawater. Our findings suggest that for the seasonal differences in metacommunity processes, BCCs of subtropical summer seawater were more sensitive to temperature and were more difficult to predict than those of winter seawater in face of different intensity of thermal impacts.IMPORTANCE Understanding the mechanisms of bacterial community assembly across environmental gradients is one of the major goals of marine microbial ecology. Thermal effluents off two nuclear power plants in subtropical Daya Bay have been present for more than 20 years and have generated a comparatively stable and long thermal gradient (a temperature increase from 0 to 10°C). The environment patches across thermal gradients are heterogeneous and very strongly interconnected on a microbial scale, thus it is a useful model to study metacommunity processes (i.e., patch dynamics, species sorting, mass effects, and neutral processes) that underlie marine bacterioplankton assembly. The significance of our research is to understand how environmental conditions and dispersal-related processes interact to influence bacterioplankton metacommunity processes and their seasonal differences across thermal gradients. Our results may advance the understanding of marine microbial ecology under future global warming.

RevDate: 2018-10-27

Šulčius S, Šimoliūnas E, Alzbutas G, et al (2018)

Genomic characterization of cyanophage vB_AphaS-CL131 infecting filamentous diazotrophic cyanobacterium Aphanizomenon flos-aquae reveals novel insights into virus-bacterium interactions.

Applied and environmental microbiology pii:AEM.01311-18 [Epub ahead of print].

While filamentous cyanobacteria play a crucial role in food web dynamics and biogeochemical cycling of many aquatic ecosystems around the globe, the knowledge regarding phages infecting them is limited. Here we describe the complete genome of the virulent cyanophage vB_AphaS-CL131 (CL 131), a Siphoviridae phage that infects filamentous diazotrophic bloom forming cyanobacterium Aphanizomenon flos-aquae in the brackish Baltic Sea. CL 131 features a 112793 bp dsDNA genome, encompassing 149 putative open reading frames (ORFs), of which the majority (86%) lack sequence homology to genes with known functions in other bacteriophages or bacteria. Phylogenetic analysis revealed that CL 131 possibly represents a new evolutionary lineage within the group of cyanophages infecting filamentous cyanobacteria, which form a separate cluster compared to phages infecting unicellular cyanobacteria. CL 131 encodes a putative type V-U2 CRISPR-Cas system with one spacer (out of 10) targeting a DNA primase pseudogene in a cyanobacterium and a putative type II toxin-antitoxin system, consisting of GNAT family N-acetyltransferase and a protein of unknown function containing the PRK09726 domain (characteristic of HipB antitoxins). Comparison of CL 131 proteins to reads from Baltic Sea and other available fresh- and brackish-water metagenomes and analysis of CRISPR-Cas arrays in publicly available A. flos-aquae genomes demonstrated that phages similar to CL 131 are present and dynamic in the Baltic Sea and share common history with their hosts dating back at least several decades. In addition, different CRISPR-Cas systems within individual A. flos-aquae genomes targeted several sequences in the CL 131 genome, including genes related to virion structure and morphogenesis. Altogether, these findings revealed new genomic information for exploring viral diversity and provide a model system for investigation of virus-host interactions in filamentous cyanobacteria.Importance The genomic characterization of novel cyanophage vB_AphaS-CL131 and the analysis of its genomic features in the context of other viruses, metagenomic data and host CRISPR-Cas systems contribute toward better understanding of aquatic viral diversity and distribution in general and brackish water cyanophages infecting filamentous diazotrophic cyanobacteria in the Baltic Sea in particular. The results of this study revealed previously undescribed features of cyanophage genomes (e.g. self-excising intein-containing putative dCTP deaminase, putative cyanophage-encoded CRISPR-Cas and toxin-antitoxin systems) and can therefore be used to predict potential interactions between bloom-forming cyanobacteria and their cyanophages.

RevDate: 2018-10-27

De Filippis F, La Storia A, Villani F, et al (2018)

Strain-level diversity analysis of Pseudomonas fragi after in situ pangenome reconstruction shows distinctive spoilage-associated metabolic traits clearly selected by different storage conditions.

Applied and environmental microbiology pii:AEM.02212-18 [Epub ahead of print].

Microbial spoilage of raw meat causes huge economic losses every year. Understanding the microbial ecology associated to the spoilage and its dynamics during refrigerated storage of meat can help in preventing and delaying the spoilage-related activities. Raw meat microbiota is usually complex but only few members will develop during storage and cause spoilage, upon the pressure of several external factors, such as temperature and oxygen availability. We characterized the metagenome of beef packed aerobically or under-vacuum during refrigerated storage to explore how different packaging conditions may influence microbial composition and potential spoilage-associated activities. Different population dynamics and spoilage-associated genomic repertoires occurred in beef stored in air or vacuum-packaging. Moreover, pangenomics of Pseudomonas fragi strains extracted from metagenomes was carried out. We demonstrated the presence of specific, storage-driven strain-level profiles of Pseudomonas fragi, characterized by a different gene repertoire, thus potentially able to act differently during meat spoilage. The results provide new knowledge on strain-level microbial ecology associated to meat spoilage and can be of value for future strategies of spoilage prevention and food waste reduction.IMPORTANCE This work provides insights on the mechanisms involved in raw beef spoilage during refrigerated storage and on the selective pressure exerted by the packaging conditions. We highlighted the presence of different microbial metagenomes during spoilage of beef packaged aerobically or under-vacuum. The packaging condition was able to select specific Pseudomonas fragi strains, with a distinctive genomic repertoire. This study may help in deciphering the behaviour of different biomes directly in-situ in food and in understanding the specific contribution of different strains to food spoilage.

RevDate: 2018-10-26

Sharma S, P Tripathi (2018)

Gut microbiome and type 2 diabetes: where we are and where to go?.

The Journal of nutritional biochemistry, 63:101-108 pii:S0955-2863(18)30307-3 [Epub ahead of print].

Type 2 diabetes mellitus (T2D) is a highly prevalent metabolic disorder characterized by an imbalance in blood glucose level, altered lipid profile and high blood pressure. Genetic constituents, high-fat and high-energy dietary habits, and a sedentary lifestyle are three major factors that contribute to high risk of T2D. Several studies have reported gut microbiome dysbiosis as a factor in rapid progression of insulin resistance in T2D that accounts for about 90% of all diabetes cases worldwide. The gut microbiome dysbiosis may reshape intestinal barrier functions and host metabolic and signaling pathways, which are directly or indirectly related to the insulin resistance in T2D. Thousands of the metabolites derived from microbes interact with the epithelial, hepatic and cardiac cell receptors that modulate host physiology. Xenobiotics including dietary components, antibiotics and nonsteroidal anti-inflammatory drugs strongly affect the gut microbial composition and can promote dysbiosis. Any change in the gut microbiota can shift the host metabolism towards increased energy harvest during diabetes and obesity. However, the exact mechanisms behind the dynamics of gut microbes and their impact on host metabolism at the molecular level are yet to be deciphered. We reviewed the published literature for better understanding of the dynamics of gut microbiota, factors that potentially induce gut microbiome dysbiosis and their relation to the progression of T2D. Special emphasis was also given to understand the gut microbiome induced breaching of intestinal barriers and/or tight junctions and their relation to insulin resistance.

RevDate: 2018-10-26

Götz F, Pjevac P, Markert S, et al (2018)

Transcriptomic and Proteomic Insight into the Mechanism of Cyclooctasulfur- versus Thiosulfate-Oxidation by the Chemolithoautotroph Sulfurimonas denitrificans.

Environmental microbiology [Epub ahead of print].

Chemoautotrophic bacteria belonging to the genus Sulfurimonas (class Campylobacteria) were previously identified as key players in the turnover of zero-valence sulfur, a central intermediate in the marine sulfur cycle. S. denitrificans was further shown to be able to oxidize cyclooctasulfur (S8). However, at present the mechanism of activation and metabolism of cyclooctasulfur is not known. Here, we assessed the transcriptome and proteome of S. denitrificans grown with either thiosulfate or S8 as the electron donor. While the overall expression profiles under the two growth conditions were rather similar, distinct differences were observed that could be attributed to the utilization of S8 . This included a higher abundance of expressed genes related to surface attachment in the presence of S8 , and the differential regulation of the sulfur-oxidation multienzyme complex (SOX), which in S. denitrificans is encoded in two gene clusters: soxABXY1 Z1 and soxCDY2 Z2 . While the proteins of both clusters were present with thiosulfate, only proteins of the soxCDY2 Z2 were detected at significant levels with S8 . Based on these findings a model for the oxidation of S8 is proposed. Our results have implications for interpreting metatranscriptomic and -proteomic data and for the observed high level of diversification of soxY2 Z2 among sulfur-oxidizing Campylobacteria. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-26

Almeida OGG, ECP De Martinis (2018)

Bioinformatics tools to assess metagenomic data for applied microbiology.

Applied microbiology and biotechnology pii:10.1007/s00253-018-9464-9 [Epub ahead of print].

The reduction of the price of DNA sequencing has resulted in the emergence of large data sets to handle and analyze, especially in microbial ecosystems, which are characterized by high taxonomic and functional diversities. To assess the properties of these complex ecosystems, a conceptual background of the application of NGS technology and bioinformatics analysis to metagenomics is required. Accordingly, this article presents an overview of the evolution of knowledge of microbial ecology from traditional culture-dependent methods to culture-independent methods and the last frontier in knowledge, metagenomics. Topics that will be covered include sample preparation for NGS, starting with total DNA extraction and library preparation, followed by a brief discussion of the chemistry of NGS to help provide an understanding of which bioinformatics pipeline approach may be helpful for achieving a researcher's goals. The importance of selecting appropriate sequencing coverage and depth parameters to obtain a suitable measure of microbial diversity is discussed. As all DNA sequencing processes produce base-calling errors that compromise data analysis, including genome assembly and microbial functional analysis, dedicated software is presented and conceptually discussed with regard to potential applications in the general microbial ecology field.

RevDate: 2018-10-25

Bosmans L, Pozo MI, Verreth C, et al (2018)

Habitat-specific variation in gut microbial communities and pathogen prevalence in bumblebee queens (Bombus terrestris).

PloS one, 13(10):e0204612 pii:PONE-D-18-16011.

Gut microbial communities are critical for the health of many insect species. However, little is known about how gut microbial communities respond to anthropogenic changes and how such changes affect host-pathogen interactions. In this study, we used deep sequencing to investigate and compare the composition of gut microbial communities within the midgut and ileum (both bacteria and fungi) in Bombus terrestris queens collected from natural (forest) and urbanized habitats. Additionally, we investigated whether the variation in gut microbial communities under each habitat affected the prevalence of two important bumblebee pathogens that have recently been associated with Bombus declines (Crithidia bombi and Nosema bombi). Microbial community composition differed strongly among habitat types, both for fungi and bacteria. Fungi were almost exclusively associated with bumblebee queens from the forest habitats, and were not commonly detected in bumblebee queens from the urban sites. Further, gut bacterial communities of urban B. terrestris specimens were strongly dominated by bee-specific core bacteria like Snodgrassella (Betaproteobacteria) and Gilliamella (Gammaproteobacteria), whereas specimens from the forest sites contained a huge fraction of environmental bacteria. Pathogen infection was very low in urban populations and infection by Nosema was only observed in specimens collected from forest habitats. No significant relationship was found between pathogen prevalence and microbial gut diversity. However, there was a significant and negative relationship between prevalence of Nosema and relative abundance of the core resident Snodgrassella, supporting its role in pathogen defense. Overall, our results indicate that land-use change may lead to different microbial gut communities in bumblebees, which may have implications for bumblebee health, survival and overall fitness.

RevDate: 2018-10-25

Kamitani M, Nagano AJ, Honjo MN, et al (2018)

A Survey on Plant Viruses in Natural Brassicaceae Communities Using RNA-Seq.

Microbial ecology pii:10.1007/s00248-018-1271-4 [Epub ahead of print].

Studies on plant viruses are biased towards crop diseases and little is known about viruses in natural vegetation. We conducted extensive surveys of plant viruses in wild Brassicaceae plants occurring in three local plant communities in central Japan. We applied RNA-Seq with selective depletion of rRNA, which allowed us to detect infections of all genome-reported viruses simultaneously. Infections of Turnip mosaic virus (TuMV), Cucumber mosaic virus (CMV), Brassica yellows virus, Pelargonium zonate spot virus, and Arabidopsis halleri partitivirus 1 were detected from the two perennial species, Arabidopsis halleri subsp. gemmifera and Rorippa indica. De novo assembly further detected partial sequences of a putative novel virus in Arabis fragellosa. Virus species composition and infection rate differed depending on site and plant species. Viruses were most frequently detected from the perennial clonal plant, A. halleri, in which a high clonal transmission rate of viruses across multiple years was confirmed. Phylogenetic analysis of TuMV and CMV showed that virus strains from wild Brassicaceae were included as a major clade of these viruses with other reported strains from crop plants, suggesting that viruses were shared among wild plants and crops. Our studies indicated that distribution of viruses in natural plant populations are determined by the combinations of life histories of viruses and hosts. Revealing viral distribution in the natural plant communities improves our knowledge on the ecology of plant viruses.

RevDate: 2018-10-25

Li CX, Fan YF, Luan W, et al (2018)

Titanium Ions Inhibit the Bacteria in Vase Solutions of Freshly Cut Gerbera jamesonii and Extend the Flower Longevity.

Microbial ecology pii:10.1007/s00248-018-1273-2 [Epub ahead of print].

Titanium ions significantly promote plant growth, but the mechanism is still unclear. Cut flowers are ideal materials for the study of plant growth and senescence. In this study, freshly cut Gerbera jamesonii were used to study the effects of titanium ions (8 mg/L) on the flower longevity. Flowering observation showed that the gerbera vase life was significantly prolonged in the presence of titanium ions. Plate colony counts showed that the amounts of bacteria in the vase solution of the control group were approximately 1700 times more than that of titanium ion treatment group. High-throughput sequencing was used to determine the sequences of 16S rRNA gene V3-V4 variable regions of the vase solutions to analyze bacterial species, their average proportions, and absolute abundance. The results showed that the titanium ions reduced the entire bacterial counts as well as altered the absolute abundance of different bacterial species in the vase solution. The most prevalent bacteria were mainly Enterobacteriaceae, Pseudomonas veronii, Pseudomonas sp., Delftia sp., Agrobacterium sp., Sphingobacterium multivorum, Acinetobacter johnsonii, and Clostridiaceae. In combination with plate colony counts, we demonstrated that all the bacterial growths were significantly inhibited by titanium ions, regardless of their average proportions increased or decreased. These results showed that titanium ions could extend effectively the longevity of gerberas and possess the broad-spectrum antibacterial properties. This study provides a basis for further mechanism exploration of titanium ions action and its applications in cut flower preservation and agricultural production.

RevDate: 2018-10-25

Almendras K, Leiva D, Carú M, et al (2018)

Carbon Consumption Patterns of Microbial Communities Associated with Peltigera Lichens from a Chilean Temperate Forest.

Molecules (Basel, Switzerland), 23(11): pii:molecules23112746.

Lichens are a symbiotic association between a fungus and a green alga or a cyanobacterium, or both. They can grow in practically any terrestrial environment and play crucial roles in ecosystems, such as assisting in soil formation and degrading soil organic matter. In their thalli, they can host a wide diversity of non-photoautotrophic microorganisms, including bacteria, which play important functions and are considered key components of the lichens. In this work, using the BioLog® EcoPlate system, we studied the consumption kinetics of different carbon-sources by microbial communities associated with the thallus and the substrate of Peltigera lichens growing in a Chilean temperate rain forest dominated by Nothofagus pumilio. Based on the similarity of the consumption of 31 carbon-sources, three groups were formed. Among them, one group clustered the microbial metabolic profiles of almost all the substrates from one of the sampling sites, which exhibited the highest levels of consumption of the carbon-sources, and another group gathered the microbial metabolic profiles from the lichen thalli with the most abundant mycobiont haplotypes. These results suggest that the lichen thallus has a higher impact on the metabolism of its microbiome than on the microbial community of its substrate, with the latter being more diverse in terms of the metabolized sources and whose activity level is probably related to the availability of soil nutrients. However, although significant differences were detected in the microbial consumption of several carbon-sources when comparing the lichen thallus and the underlying substrate, d-mannitol, l-asparagine, and l-serine were intensively metabolized by both communities, suggesting that they share some microbial groups. Likewise, some communities showed high consumption of 2-hydroxybenzoic acid, d-galacturonic acid, and itaconic acid; these could serve as suitable sources of microorganisms as bioresources of novel bioactive compounds with biotechnological applications.

RevDate: 2018-10-25

Hird SM, Ganz H, Eisen JA, et al (2018)

The Cloacal Microbiome of Five Wild Duck Species Varies by Species and Influenza A Virus Infection Status.

mSphere, 3(5): pii:3/5/e00382-18.

Waterfowl, especially ducks of the genus Anas, are natural reservoir species for influenza A virus (IAV). Duck populations contain nearly all the known diversity of IAVs, and the birds are asymptomatic to infection. Previous work established that IAV infection status is correlated with changes in the cloacal microbiome in juvenile mallards. Here, we analyze five Anas species to determine whether these duck species have similar IAV+ and IAV- cloacal microbiomes, or if the relationships among a host, influenza virus, and the microbiome are species specific. We assessed taxonomic composition of the microbiome, alpha diversity, and beta diversity and found very few patterns related to microbiome and infection status across species, while detecting strong differences within species. A host species-specific signal was stronger in IAV- ducks than IAV+ ducks, and the effect size of host species on the microbiome was three times higher in IAV- birds than IAV+ birds. The mallards and the northern shovelers, the species with highest sample sizes but also with differing feeding ecology, showed especially contrasting patterns in microbiome composition, alpha diversity, and beta diversity. Our results indicate that the microbiome may have a unique relationship with influenza virus infection at the species level.IMPORTANCE Waterfowl are natural reservoir species for influenza A virus (IAV). Thus, they maintain high levels of pathogen diversity, are asymptomatic to the infection, and also contribute to the risk of a global influenza pandemic. An individual's microbiome is a critical part in how a vertebrate manages pathogens and illness. Here, we describe the cloacal microbiome of 300 wild ducks, from five species (four with previously undescribed microbiomes), including both IAV-negative and IAV-positive individuals. We demonstrate that there is not one consistent "flu-like" microbiome or response to flu across species. Individual duck species appear to have unique relationships between their microbiomes and IAV, and IAV-negative birds have a stronger tie to host species than the IAV-positive birds. In a broad context, understanding the role of the microbiome in IAV reservoir species may have future implications for avian disease management.

RevDate: 2018-10-25

Tackmann J, Arora N, Schmidt TSB, et al (2018)

Ecologically informed microbial biomarkers and accurate classification of mixed and unmixed samples in an extensive cross-study of human body sites.

Microbiome, 6(1):192 pii:10.1186/s40168-018-0565-6.

BACKGROUND: The identification of body site-specific microbial biomarkers and their use for classification tasks have promising applications in medicine, microbial ecology, and forensics. Previous studies have characterized site-specific microbiota and shown that sample origin can be accurately predicted by microbial content. However, these studies were usually restricted to single datasets with consistent experimental methods and conditions, as well as comparatively small sample numbers. The effects of study-specific biases and statistical power on classification performance and biomarker identification thus remain poorly understood. Furthermore, reliable detection in mixtures of different body sites or with noise from environmental contamination has rarely been investigated thus far. Finally, the impact of ecological associations between microbes on biomarker discovery was usually not considered in previous work.

RESULTS: Here we present the analysis of one of the largest cross-study sequencing datasets of microbial communities from human body sites (15,082 samples from 57 publicly available studies). We show that training a Random Forest Classifier on this aggregated dataset increases prediction performance for body sites by 35% compared to a single-study classifier. Using simulated datasets, we further demonstrate that the source of different microbial contributions in mixtures of different body sites or with soil can be detected starting at 1% of the total microbial community. We apply a biomarker selection method that excludes indirect environmental associations driven by microbe-microbe associations, yielding a parsimonious set of highly predictive taxa including novel biomarkers and excluding many previously reported taxa. We find a considerable fraction of unclassified biomarkers ("microbial dark matter") and observe that negatively associated taxa have a surprisingly high impact on classification performance. We further detect a significant enrichment of rod-shaped, motile, and sporulating taxa for feces biomarkers, consistent with a highly competitive environment.

CONCLUSIONS: Our machine learning model shows strong body site classification performance, both in single-source samples and mixtures, making it promising for tasks requiring high accuracy, such as forensic applications. We report a core set of ecologically informed biomarkers, inferred across a wide range of experimental protocols and conditions, providing the most concise, general, and least biased overview of body site-associated microbes to date.

RevDate: 2018-10-24

Tan CK, Ikhsan NFM, Suyub IB, et al (2018)

Comparative study of gut microbiota in wild and captive Malaysian Mahseer (Tor tambroides).

MicrobiologyOpen [Epub ahead of print].

AIMS: The aim of this study was to identify and compare the gut microbial community of wild and captive Tor tambroides through 16S rDNA metagenetic sequencing followed by functions prediction.

METHODS AND RESULTS: The library of 16S rDNA V3-V4 hypervariable regions of gut microbiota was amplified and sequenced using Illumina MiSeq. The sequencing data were analyzed using Quantitative Insights into Microbial Ecology (QIIME) pipeline and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). The most abundant bacterial phyla in both wild and captive T. tambroides were Firmicutes, Proteobacteria, Fusobacteria and Bacteroidetes. Cetobacterium spp., Peptostreptococcaceae family, Bacteroides spp., Phosphate solubilizing bacteria PSB-M-3, and Vibrio spp. were five most abundant OTU in wild T. tambroides as compared to Cetobacterium spp., Citrobacter spp., Aeromonadaceae family, Peptostreptococcaceae family and Turicibacter spp. in captive T. tambroides.

CONCLUSION: In this study, the specimens of the wild T. tambroides contain more diverse gut microbiota than of the captive ones. The results suggested that Cetobacterium spp. is one of the core microbiota in guts of T. tambroides. Besides, high abundant Bacteroides spp., Citrobacter spp., Turicibacter spp., and Bacillus spp. may provide important functions in T. tambroides guts.

The results of this study provide significant information of T. tambroides gut microbiota for further understanding of their physiological functions including growth and disease resistance.

RevDate: 2018-10-24

De Vrieze J, Colica G, Pintucci C, et al (2018)

Resource recovery from pig manure via an integrated approach: A technical and economic assessment for full-scale applications.

Bioresource technology pii:S0960-8524(18)31438-X [Epub ahead of print].

Intensive livestock farming cannot be uncoupled from the massive production of manure, requiring adequate management to avoid environmental damage. The high carbon, nitrogen and phosphorus content of pig manure enables targeted resource recovery. Here, fifteen integrated scenarios for recovery of water, nutrients and energy are compared in terms of technical feasibility and economic viability. The recovery of refined nutrients with a higher market value and quality, i.e., (NH4)2SO4 for N and struvite for P, coincided with higher net costs, compared to basic composting. The inclusion of anaerobic digestion promoted nutrient recovery efficiency, and enabled energy recovery through electricity production. Co-digestion of the manure with carbon-rich waste streams increased electricity production, but did not result in lower process costs. Overall, key drivers for the selection of the optimal manure treatment scenario will include the market demand for more refined (vs. separated or concentrated) products, and the need for renewable electricity production.

RevDate: 2018-10-26

Christiaens MER, De Vrieze J, Clinckemaillie L, et al (2018)

Anaerobic ureolysis of source-separated urine for NH3 recovery enables direct removal of divalent ions at the toilet.

Water research, 148:97-105 pii:S0043-1354(18)30818-2 [Epub ahead of print].

Source-separated urine is of interest for nutrient recovery. Most nitrogen recovery technologies rely on ammonia (NH3) as input, which requires ureolysis. As urease positive bacteria are widespread, source-separated urine is unstable, not only leading to NH3 release but also loss, odor nuisance, and downstream scaling. Hence, ureolysis ideally occurs in a closed controlled environment close to the toilet. We characterized microbial-induced ureolysis, subsequent divalent cation precipitation, and fermentation in anaerobic sequencing batch reactors (SBRs) at 15 °C and 28 °C. Temperatures were a proxy for urine hydrolysis in a wet well at street level or in the toilet, respectively. The need for inoculation and the metabolic stability was assessed by inoculation with autofermented urine or a mixture of anaerobic digestion and fermentation sludge. The highest specific ureolysis rates in the SBRs were achieved at 28 °C: 2107 ± 395 and 1948 ± 1121 mg N g VSS-1 d-1, for the mixed and autofermented inoculum, respectively. For Ca2+ and Mg2+ precipitation, and organics fermentation, autofermented urine at 28 °C performed best with 47.9 ± 16.4 mg Ca2+ g VSS-1 d-1, 8.2 ± 4.6 mg Mg2+ g VSS-1 d-1, and 623 ± 129 mg VFA-COD g VSS-1 d-1, respectively. This indicates the hydrolysis reactor should be close to the toilet. The selected inoculum did not impact ureolysis, whereas both Ca2+ and Mg2+ precipitation and fermentation were better in the SBRs with autofermented urine. Ureolysis was identified as the only process significantly impacting the microbial community, indicating external inoculation would not be required. A urine hydrolysis reactor in the toilet without external inoculation could thus serve as a controlled environment to release NH3 and remove divalent cations to prevent scaling in downstream transport and processing. For practical implementation in a household toilet, the reactor should be designed for user-friendly precipitate discharge and odor control.

RevDate: 2018-10-23

Gonzalez-Escobedo R, Briones-Roblero CI, López MF, et al (2018)

Changes in the Microbial Community of Pinus arizonica Saplings After Being Colonized by the Bark Beetle Dendroctonus rhizophagus (Curculionidae: Scolytinae).

Microbial ecology pii:10.1007/s00248-018-1274-1 [Epub ahead of print].

The death of trees is an ecological process that promotes regeneration, organic matter recycling, and the structure of communities. However, diverse biotic and abiotic factors can disturb this process. Dendroctonus bark beetles (Curculionidae: Scolytinae) are natural inhabitants of pine forests, some of which produce periodic outbreaks, killing thousands of trees in the process. These insects spend almost their entire life cycle under tree bark, where they reproduce and feed on phloem. Tunneling and feeding of the beetles result in the death of the tree and an alteration of the resident microbiota as well as the introduction of microbes that the beetles vector. To understand how microbial communities in subcortical tissues of pines change after they are colonized by the bark beetle Dendroctonus rhizophagus, we compare both the bacterial and fungal community structures in two colonization stages of Pinus arizonica (Arizona pine) employing Illumina MiSeq. Our findings showed significant differences in diversity and the dominance of bacterial community in the two colonization stages with Shannon (P = 0.004) and Simpson (P = 0.0006) indices, respectively, but not in species richness with Chao1 (P = 0.19). In contrast, fungal communities in both stages showed significant differences in species richness with Chao1 (P = 0.0003) and a diversity with Shannon index (P = 0.038), but not in the dominance with the Simpson index (P = 0.12). The β-diversity also showed significant changes in the structure of bacterial and fungal communities along the colonization stages, maintaining the dominant members in both cases. Our results suggest that microbial communities present in the Arizona pine at the tree early colonization stage by bark beetle change predictably over time.

RevDate: 2018-10-23

Zeng L, RA Burne (2018)

Essential Roles of the sppRA Fructose-Phosphate Phosphohydrolase Operon in Carbohydrate Metabolism and Virulence Expression by Streptococcus mutans.

Journal of bacteriology pii:JB.00586-18 [Epub ahead of print].

The dental caries pathogen Streptococcus mutans can ferment a variety of sugars to produce organic acids. Exposure of S. mutans to certain non-metabolizable carbohydrates such as xylitol impairs growth and can cause cell death. Recently, the presence of a sugar-phosphate stress in S. mutans was demonstrated using a mutant lacking 1-phosphofructokinase (FruK) that accumulates fructose-1-phosphate (F-1-P). Here we studied an operon in S. mutans, sppRA, which was highly expressed in the fruK mutant. Biochemical characterization of a recombinant SppA protein indicated that it possessed hexose-phosphate phosphohydrolase activity, with preferences for F-1-P and, to a lesser degree, fructose-6-phosphate (F-6-P). SppA activity was stimulated by Mg2+ and Mn2+, but inhibited by NaF. SppR, a DeoR-family regulator, repressed the expression of the sppRA operon to minimum levels in the absence of the fructose-derived metabolites, F-1-P and likely also F-6-P. Accumulation of F-1-P, as a result of growth on fructose, not only induced sppA expression, it significantly altered biofilm maturation through increased cell lysis and enhanced extracellular DNA release. Constitutive expression of sppA, via a plasmid or by deleting sppR, greatly alleviated fructose-induced stress in a fruK mutant, enhanced resistance to xylitol, and reversed effects of fructose on biofilm formation. Finally, by identifying three additional putative phosphatases that are capable of promoting sugar-phosphate tolerance, we show that S. mutans is capable of mounting a sugar-phosphate stress response by modulating the levels of certain glycolytic intermediates, functions that are interconnected with the ability of the organism to manifest key virulence behaviors.IMPORTANCEStreptococcus mutans is a major etiologic agent for dental caries, primarily due to its ability to form biofilms on tooth surface and to convert carbohydrates into organic acids. We have discovered a two-gene operon in S. mutans that regulates fructose metabolism by controlling the levels of fructose-1-phosphate, a potential signaling compound that affects bacterial behaviors. With fructose becoming increasingly common and abundant in the human diet, we reveal the ways fructose may alter bacterial development, stress tolerance, and microbial ecology in the oral cavity to promote oral diseases.

RevDate: 2018-10-24

Lavoie C, Courcelle M, Redivo B, et al (2018)

Structural and compositional mismatch between captive and wild Atlantic salmon (Salmo salar) parrs' gut microbiota highlights the relevance of integrating molecular ecology for management and conservation methods.

Evolutionary applications, 11(9):1671-1685 pii:EVA12658.

Stocking methods are used in the Province of Quebec to restore Salmo salar populations. However, Atlantic salmon stocked juveniles show higher mortality rates than wild ones when introduced into nature. Hatchery environment, which greatly differs from the natural environment, is identified as the main driver of the phenotypic mismatch between captive and wild parrs. The latter is also suspected to impact the gut microbiota composition, which can be associated with essential metabolic functions for their host. We hypothesized that hatchery-raised parrs potentially recruit gut microbial communities that are different from those recruited in the wild. This study evaluated the impacts of artificial rearing on gut microbiota composition in 0+ parrs meant for stocking in two distinct Canadian rivers: Rimouski and Malbaie (Quebec, Canada). Striking differences between hatchery and wild-born parrs' gut microbiota suggest that microbiota could be another factor that could impact their survival in the targeted river, because the microbiome is narrowly related to host physiology. For instance, major commensals belonging to Enterobacteriaceae and Clostridiacea from wild parrs' gut microbiota were substituted in captive parrs by lactic acid bacteria from the Lactobacillaceae family. Overall, captive parrs host a generalist bacterial community whereas wild parrs' microbiota is much more specialized. This is the very first study demonstrating extensive impact of captive rearing on intestinal microbiota composition in Atlantic salmon intended for wild population stocking. Our results strongly suggest the need to implement microbial ecology concepts into conservation management of endangered salmon stocks supplemented with hatchery-reared parrs.

RevDate: 2018-10-21

Li T, Qi M, Gatesoupe FJ, et al (2018)

Adaptation to Fasting in Crucian Carp (Carassius auratus): Gut Microbiota and Its Correlative Relationship with Immune Function.

Microbial ecology pii:10.1007/s00248-018-1275-0 [Epub ahead of print].

Fasting influences the overall physiology of fish, and the knowledge how the gut microbiota, growth performances, and immune function in response to intermittent and long-term fasting is still insufficient. Here, we characterized the effects of fasting on the host-gut microbiota in crucian carp, which would enhance our insight into physiological adaptation to fasting. To achieve this, we investigated the gut microbial communities of crucian carp with different fasting stress, and corresponding immune and growth parameters. The gut microbial communities were structured into four clusters according to different fasting stress, namely one control group (feed regularly), two intermittent fasting groups (fasting period and re-feeding period, respectively), and one long-term fasting group. Intermittent fasting significantly improved the activity of superoxide dismutase (SOD) and lysozyme (LZM) (ANOVA, p < 0.05) and significantly increased alpha diversity and ecosystem stability of gut microbiota (ANOVA, p < 0.05). Gut length (GL) and condition factor (CF) showed no significant difference between the control group (CG) and intermittent fasting group under re-feeding period (RIF) (ANOVA, p = 0.11), but relative gut length (RGL) in group RIF was higher than that in the CG (ANOVA, p = 0.00). The bacterial genera Bacteroides, Akkermansia, and Erysipelotrichaceae were enriched in fishes under intermittent fasting. Two Bacteroides OTUs (OTU50 and OTU1292) correlated positively with immune (SOD, complement, and LZM) and growth (GL and RGL) parameters. These results highlight the possible interplay between growth performances, immune function, and gut microbiota in response to fasting.

RevDate: 2018-10-21

Free A, McDonald MA, E Pagaling (2018)

Diversity-Function Relationships in Natural, Applied, and Engineered Microbial Ecosystems.

Advances in applied microbiology, 105:131-189.

The connection between ecosystem function and taxonomic diversity has been of interest and relevance to macroecologists for decades. After many years of lagging behind due to the difficulty of assigning both taxonomy and function to poorly distinguishable microscopic cells, microbial ecology now has access to a suite of powerful molecular tools which allow its practitioners to generate data relating to diversity and function of a microbial community on an unprecedented scale. Instead, the problem facing today's microbial ecologists is coupling the ease of generation of these datasets with the formulation and testing of workable hypotheses relating the diversity and function of environmental, host-associated, and engineered microbial communities. Here, we review the current state of knowledge regarding the links between taxonomic alpha- and beta-diversity and ecosystem function, comparing our knowledge in this area to that obtained by macroecologists who use more traditional techniques. We consider the methodologies that can be applied to study these properties and how successful they are at linking function to diversity, using examples from the study of model microbial ecosystems, methanogenic bioreactors (anaerobic digesters), and host-associated microbiota. Finally, we assess ways in which our newly acquired understanding might be used to manipulate diversity in ecosystems of interest in order to improve function for the benefit of us or the environment in general through the provision of ecosystem services.

RevDate: 2018-10-20

Deja-Sikora E, Gołębiewski M, Kalwasińska A, et al (2018)

Comamonadaceae OTU as a Remnant of an Ancient Microbial Community in Sulfidic Waters.

Microbial ecology pii:10.1007/s00248-018-1270-5 [Epub ahead of print].

Intraterrestrial waters harbor microbial communities being extensively studied to understand microbial processes underlying subsurface ecosystem functioning. This paper provides the results of an investigation on the microbiomes of unique, subsurface sulfidic waters associated with Upper Jurassic, Cretaceous, and Miocene sediments. We used high-throughput 16S rDNA amplicon sequencing to reveal the structure of bacterial and archaeal communities in water samples differing in sulfide content (20-960 mg/dm3), salinity (1.3-3.2%), and depth of extraction (60-660 m below ground level). Composition of the bacterial communities strongly varied across the samples; however, the bacteria participating in the sulfur cycle were common in all sulfidic waters. The shallowest borehole water (60 m bgl) was dominated by sulfur-oxidizing Epsilonproteobacteria (Sulfurimonas, Sulfurovum). In the waters collected from greater depths (148-300 m bgl), the prevalence of Betaproteobacteria (Comamonadaceae) and sulfate/sulfur-reducing Deltaproteobacteria (Desulfopila, Desulfomicrobium, MSBL7) was observed. Sulfate reducers (members of Clostridia: Candidatus Desulforudis) were the most abundant bacteria in the deepest borehole water (660 m bgl). Out of 850 bacterial OTUs, only one, affiliated with the Comamonadaceae family, was found abundant (> 1% of total bacterial sequences) in all samples. Contribution of Archaea to the whole microbial communities was lower than 0.5%. Archaeal communities did not differ across the samples and they consisted of Halobacteriaceae. Out of 372 archaeal OTUs, five, belonging to the four genera Natronomonas, Halorubrum, Halobellus, and Halorhabdus, were the most numerous.

RevDate: 2018-10-20

Amberkar U, Khandeparker R, P Parab (2018)

Nitrate Reductase Gene Expression in Idiomarina Strain cos21 Obtained from Oxygen Minimum Zone of Arabian Sea.

Current microbiology pii:10.1007/s00284-018-1585-y [Epub ahead of print].

This study analyses the induction and repression of nitrate reduction activity in a batch culture of Idiomarina strain cos21. On a change from aerobic to anaerobic respiration, the culture entered a stationary phase. The onset of this phase showed 3.75 fold increase in mRNA levels for the nitrate reductase enzyme. mRNA accumulated very rapidly during a short period, after which its overall concentration declined to reach a lower value. The level of nitrite reductase protein reached a maximum value at 36 h of growth when the oxygen concentration dropped below 10 µM. The data set provided here confer new insights into the understanding of the physiological response of Idiomarina strain cos21 to change in oxygen concentration allowing the bacterium to survive and adapt to a new environment by dissimilatory reduction of nitrate to nitrite, which serves to provide energy as the bacteria adapt to anaerobiosis. Main strategy used here is to induce, measure, and track the expression of microbial genes, while they grow in culture conditions to better mimic interaction in a natural environment. This study will help us with a better understanding of the nitrate reduction process in the oxygen minimum zone.

RevDate: 2018-10-20

Van Houdt R, Provoost A, Van Assche A, et al (2018)

Cupriavidus metallidurans Strains with Different Mobilomes and from Distinct Environments Have Comparable Phenomes.

Genes, 9(10): pii:genes9100507.

Cupriavidus metallidurans has been mostly studied because of its resistance to numerous heavy metals and is increasingly being recovered from other environments not typified by metal contamination. They host a large and diverse mobile gene pool, next to their native megaplasmids. Here, we used comparative genomics and global metabolic comparison to assess the impact of the mobilome on growth capabilities, nutrient utilization, and sensitivity to chemicals of type strain CH34 and three isolates (NA1, NA4 and H1130). The latter were isolated from water sources aboard the International Space Station (NA1 and NA4) and from an invasive human infection (H1130). The mobilome was expanded as prophages were predicted in NA4 and H1130, and a genomic island putatively involved in abietane diterpenoids metabolism was identified in H1130. An active CRISPR-Cas system was identified in strain NA4, providing immunity to a plasmid that integrated in CH34 and NA1. No correlation between the mobilome and isolation environment was found. In addition, our comparison indicated that the metal resistance determinants and properties are conserved among these strains and thus maintained in these environments. Furthermore, all strains were highly resistant to a wide variety of chemicals, much broader than metals. Only minor differences were observed in the phenomes (measured by phenotype microarrays), despite the large difference in mobilomes and the variable (shared by two or three strains) and strain-specific genomes.

RevDate: 2018-10-17

Kowalec M, Szewczyk T, Welc-Falęciak R, et al (2018)

Rickettsiales Occurrence and Co-occurrence in Ixodes ricinus Ticks in Natural and Urban Areas.

Microbial ecology pii:10.1007/s00248-018-1269-y [Epub ahead of print].

Bacteria of Rickettsiaceae and Anaplasmataceae families include disease agents spread by Ixodes ricinus ticks, the most common tick vector in Europe. The aim of the study was to compare the prevalence and co-infection prevalence of particular tick-transmitted Rickettsiales members: Rickettsia spp. (further referred as Rs), Anaplasma phagocytophilum (Ap), and "Candidatus Neoehrlichia mikurensis" (CNM) in I. ricinus ticks in two types of areas, different in terms of human impact: natural and urban. Using additional data, we aimed at investigating co-occurrence of these Rickettsiales with Borreliella spp. A total of 4189 tick specimens, 2363 from the urban area (Warsaw park and forests) and 1826 from the natural area (forests and park in the vicinity of National Parks), were tested for the presence of Rickettsiales DNA by PCRs. The prevalence of selected Rickettsiales was twice higher in urban than natural areas (13.2% vs. 6.9%, respectively). In total ticks, the prevalence of Rs, Ap, and CNM was 6.5%, 5.3%, and 3.6% in urban areas vs. 4.4%, 1.1%, and 2.1% in natural areas, respectively. Co-infections of Rickettsiales were also more prevalent in urban areas (2.6% vs. 0.3%, respectively). The most common Rs was R. helvetica; also R. monacensis and novel "Candidatus Rickettsia mendelii" were detected. Positive association between Ap and CNM infections was discovered. Rickettsiales bacteria occurrence was not associated with Borreliella occurrence, but co-infections with these two groups were more common in ticks in urban areas. In conclusion, three groups of Rickettsiales constituted the important part of the tick pathogen community in Poland, especially in the urbanized central Poland (Mazovia). In the Warsaw agglomeration, there is a greater risk of encountering the I. ricinus tick infected with Rickettsiales and co-infected with Lyme spirochaetes, in comparison to natural areas. This finding raises the question whether cities might in fact be the hot spots for TBDs.

RevDate: 2018-10-26

Van Winckel T, Liu X, Vlaeminck SE, et al (2018)

Overcoming floc formation limitations in high-rate activated sludge systems.

Chemosphere, 215:342-352 pii:S0045-6535(18)31835-6 [Epub ahead of print].

High-rate activated sludge (HRAS) is an essential cornerstone of the pursuit towards energy positive sewage treatment through maximizing capture of organics. The capture efficiency heavily relies on the degree of solid separation achieved in the clarifiers. Limitations in the floc formation process commonly emerge in HRAS systems, with detrimental consequences for the capture of organics. This study pinpointed and overcame floc formation limitations present in full-scale HRAS reactors. Orthokinetic flocculation tests were performed with varying shear, sludge concentration, and coagulant or flocculant addition. These were analyzed with traditional and novel settling parameters and extracellular polymeric substances (EPS) measurements. HRAS was limited by insufficient collision efficiency and occurred because the solids retention time (SRT) was short and colloid loading was high. The limitation was predominantly caused by impaired flocculation rather than coagulation. In addition, the collision efficiency limitation was driven by EPS composition (low protein over polysaccharide ratio) instead of total EPS amount. Collision efficiency limitation was successfully overcome by bio-augmenting sludge from a biological nutrient removal reactor operating at long SRT which did not show any floc formation limitations. However, this action brought up a floc strength limitation. The latter was not correlated with EPS composition, but rather EPS amount and hindered settling parameters, which determined floc morphology. With this, an analysis toolkit was proposed that will enable design engineers and operators to tackle activated solid separation challenges found in HRAS systems and maximize the recovery potential of the process.

RevDate: 2018-10-27

Lee YM, Kor CT, Zhou D, et al (2018)

Impact of age at appendectomy on development of type 2 diabetes: A population-based cohort study.

PloS one, 13(10):e0205502 pii:PONE-D-18-07427.

AIM: Diabetes is a complex metabolic disease characterized by chronic low-grade inflammation in which genetic and environmental factors are involved. Growing evidence implicates that alterations of the gut microbiota potentially contribute to the emergence of metabolic diseases. The human appendix has more recently been recognized as a microbial reservoir for repopulating the gastrointestinal tract and an important part of the immune system. Thus, appendectomy may influence microbial ecology and immune function. This study investigated the association between appendectomy and type 2 diabetes risk.

METHODS: We analyzed a cohort of 10954 patients who underwent appendectomy between 1998 and 2013 based on the Taiwan National Health Insurance Program database. A comparison cohort of 43815 persons without appendectomy was selected randomly and matched by sex, age, comorbidities, and index year. To ensure reliability of the results, a sensitivity analysis using a propensity score-matched study was performed. We observed the subsequent development of type 2 diabetes in both cohorts.

RESULTS: Although the overall incidence of type 2 diabetes in the appendectomy patients was 7.9% higher than that in the non-appendectomy patients, it was not statistically significant (95% confidence interval [CI], 0.997-1.168) after the adjustment of confounding factors. Multivariate regression analysis revealed that the adjusted hazard ratio (HR) of type 2 diabetes was 1.347 for appendectomy patients < 30 years of age (95% CI, 1.009-1.798) compared to non-appendectomy patients. The incidence of type 2 diabetes was higher within 3 years of post-appendectomy follow-up than for non-appendectomy patients (HR, 2.017; 95% CI, 1.07-3.802). Age impacted the association between appendectomy and type 2 diabetes risk (Pinteraction = 0.002); in contrast, sex did not affect the association between appendectomy and type 2 diabetes risk (Pinteraction = 0.88).

CONCLUSIONS: Our study results suggest that appendectomy increases type 2 diabetes risk, particularly when performed prior to middle age.

RevDate: 2018-10-16

Szczepańska A, Kiewra D, K Guz-Regner (2018)

Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to Bacillus thuringiensis isolates: preliminary study.

Parasitology research pii:10.1007/s00436-018-6096-z [Epub ahead of print].

Bacillus thuringiensis is a highly specific entomopathogenic microorganism. Although defined as having properties which work against insects, its role in the control of tick populations is still insufficiently known. In our bioassay, four environmental strains of B. thuringiensis, along with one commercially available product (Vectobac), have been used against ticks. Vectobac turned out to be ineffective in the biocontrol of ticks; however, two of environmental B. thuringiensis strains proved to be efficient against both Ixodes ricinus and Dermacentor reticulatus. In those cases, the mortality rate for ticks was assessed as being up to 80%, and LC50 ranged between 9.1 × 106 and 1.3 × 1015 (cfu/ml). Dermacentor reticulatus males were the most sensitive to bacteria. The similarity between the most and least efficient B. thuringiensis strains in enzymatic profiles-including lipases, phosphatases, proteases, and chitinases-may indicate a limited role of detected enzymes in the pathogenicity profile of bacterial strains against ticks.

RevDate: 2018-10-23

Liu K, Liu Y, Han BP, et al (2018)

Bacterial community changes in a glacial-fed Tibetan lake are correlated with glacial melting.

The Science of the total environment, 651(Pt 2):2059-2067 pii:S0048-9697(18)33983-4 [Epub ahead of print].

Climate change-induced glacial melting is a global phenomenon. The effects of climate change-induced melting on the microbial ecology in different glacial-fed aquatic systems have been well illuminated, but the resolution of seasonal dynamics was still limited. Here, we studied bacterial community composition and diversity in a glacial-fed Tibetan lake, Lake Ranwu, to elucidate how glacial-fed aquatic ecosystems respond to the seasonal glacial melting. Obvious seasonal variations of bacterial dominant groups were found in Lake Ranwu and inlet rivers. In April, the majority of OTUs belonged to the Bacteroidetes, Actinobacteria and Proteobacteria. The Proteobacteria increased to the most abundant phylum in July and November, while the Bacteroidetes and Actinobacteria decreased about 50% over seasons. Most key discriminant taxa of each season's community strongly associated with specific environmental variables, suggesting their adaptation to seasonal environments. Bacterial alpha diversity varied among seasons and exhibited strongly negative correlations with conductivity. Conductivity was the major driving force in determining the seasonal variation of bacterial community composition. Fluctuated conductivity was one of the consequences of seasonal melting of glaciers. This study offered evidence for the unique seasonal dynamics pattern of bacterial communities responding to glacial melting. Moreover, this study may provide a reference for assessing the long-term effects of glacial retreat on glacial-fed aquatic ecosystems.

RevDate: 2018-10-15

Stegen JC, AE Goldman (2018)

WHONDRS: a Community Resource for Studying Dynamic River Corridors.

mSystems, 3(5): pii:mSystems00151-18.

The Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) aims to galvanize a global community to provide the scientific basis for improved management of dynamic river corridors. WHONDRS is a global research consortium working to understand connections among dynamic hydrology, biogeochemistry, and microbiology in river corridors from local to global scales. WHONDRS ascribes to the perspective that resources, knowledge, and data belong to the community as a whole and that science advances more rapidly and more robustly through community ownership. As such, WHONDRS provides free access to novel instrumentation, molecular analysis, and well-curated data associated with river corridor hydrology, biogeochemistry, and microbiology. There are a number of ways to be involved in WHONDRS, ranging from one-time surface water sampling to installation of WHONDRS-developed multiparameter sensors for continuous monitoring. WHONDRS hinges on broad involvement, and we encourage all interested parties to contact us and become part of the consortium.

RevDate: 2018-10-17

Trubl G, Jang HB, Roux S, et al (2018)

Soil Viruses Are Underexplored Players in Ecosystem Carbon Processing.

mSystems, 3(5): pii:mSystems00076-18.

Rapidly thawing permafrost harbors ∼30 to 50% of global soil carbon, and the fate of this carbon remains unknown. Microorganisms will play a central role in its fate, and their viruses could modulate that impact via induced mortality and metabolic controls. Because of the challenges of recovering viruses from soils, little is known about soil viruses or their role(s) in microbial biogeochemical cycling. Here, we describe 53 viral populations (viral operational taxonomic units [vOTUs]) recovered from seven quantitatively derived (i.e., not multiple-displacement-amplified) viral-particle metagenomes (viromes) along a permafrost thaw gradient at the Stordalen Mire field site in northern Sweden. Only 15% of these vOTUs had genetic similarity to publicly available viruses in the RefSeq database, and ∼30% of the genes could be annotated, supporting the concept of soils as reservoirs of substantial undescribed viral genetic diversity. The vOTUs exhibited distinct ecology, with different distributions along the thaw gradient habitats, and a shift from soil-virus-like assemblages in the dry palsas to aquatic-virus-like assemblages in the inundated fen. Seventeen vOTUs were linked to microbial hosts (in silico), implicating viruses in infecting abundant microbial lineages from Acidobacteria, Verrucomicrobia, and Deltaproteobacteria, including those encoding key biogeochemical functions such as organic matter degradation. Thirty auxiliary metabolic genes (AMGs) were identified and suggested virus-mediated modulation of central carbon metabolism, soil organic matter degradation, polysaccharide binding, and regulation of sporulation. Together, these findings suggest that these soil viruses have distinct ecology, impact host-mediated biogeochemistry, and likely impact ecosystem function in the rapidly changing Arctic. IMPORTANCE This work is part of a 10-year project to examine thawing permafrost peatlands and is the first virome-particle-based approach to characterize viruses in these systems. This method yielded >2-fold-more viral populations (vOTUs) per gigabase of metagenome than vOTUs derived from bulk-soil metagenomes from the same site (J. B. Emerson, S. Roux, J. R. Brum, B. Bolduc, et al., Nat Microbiol 3:870-880, 2018, We compared the ecology of the recovered vOTUs along a permafrost thaw gradient and found (i) habitat specificity, (ii) a shift in viral community identity from soil-like to aquatic-like viruses, (iii) infection of dominant microbial hosts, and (iv) carriage of host metabolic genes. These vOTUs can impact ecosystem carbon processing via top-down (inferred from lysing dominant microbial hosts) and bottom-up (inferred from carriage of auxiliary metabolic genes) controls. This work serves as a foundation which future studies can build upon to increase our understanding of the soil virosphere and how viruses affect soil ecosystem services.

RevDate: 2018-10-17

Ziadi M, Bouzaiene T, M'Hir S, et al (2018)

Evaluation of the Efficiency of Ethanol Precipitation and Ultrafiltration on the Purification and Characteristics of Exopolysaccharides Produced by Three Lactic Acid Bacteria.

BioMed research international, 2018:1896240.

Exopolysaccharides (EPS) produced by three Lactic Acid Bacteria strains, Lactococcus lactis SLT10, Lactobacillus plantarum C7, and Leuconostoc mesenteroides B3, were isolated using two methods: ethanol precipitation (EPS-ETOH) and ultrafiltration (EPS-UF) through a 10 KDa cut-off membrane. EPS recovery by ultrafiltration was higher than ethanol precipitation for Lactococcus lactis SLT10 and Lactobacillus plantarum C7. However, it was similar with both methods for Leuconostoc mesenteroides B3. The monomer composition of the EPS fractions revealed differences in structures and molar ratios between the two studied methods. EPS isolated from Lactococcus lactis SLT10 are composed of glucose and mannose for EPS-ETOH against glucose, mannose, and rhamnose for EPS-UF. EPS extracted from Lactobacillus plantarum C7 and Leuconostoc mesenteroides B3 showed similar composition (glucose and mannose) but different molar ratios. The molecular weights of the different EPS fractions ranged from 11.6±1.83 to 62.4±2.94 kDa. Molecular weights of EPS-ETOH fractions were higher than those of EPS-UF fractions. Fourier transform infrared (FTIR) analysis revealed a similarity in the distribution of the functional groups (O-H, C-H, C=O, -COO, and C-O-C) between the EPS isolated from the three strains.

RevDate: 2018-10-17

D'Amico F, Candela M, Turroni S, et al (2018)

The Rootstock Regulates Microbiome Diversity in Root and Rhizosphere Compartments of Vitis vinifera Cultivar Lambrusco.

Frontiers in microbiology, 9:2240.

Plants belonging to Vitis vinifera varieties are usually grafted on different rootstocks to enhance the plant defenses against pathogens and increase productivity under harsh environmental conditions. Particularly, in Emilia-Romagna region (Italy), Vitis vinifera cultivar Lambrusco can be grafted on a hybrid of V. berlandieri × V. riparia (5BB) or V. berlandieri × V. rupestris (1103P). However, the latter shows potassium absorption problems, with a consequent reduction in grapevine production. Since it has recently been demonstrated that the rootstock has the potential to select for different microorganisms at the root-soil interface, here we hypothesized that the potassium deficiency of 1103P could be partially accounted for by the peculiarities of the rootstock microbiome. We thus employed 16S rRNA sequencing to compare root and rhizosphere microbiomes in plants of V. vinifera cultivar Lambrusco grafted on the two aforementioned rootstocks. According to our findings, 1103P shows a reduced diversity in root and rhizosphere microbiomes, including members of potassium-solubilizing microorganisms, possibly explaining the inadequate potassium absorption of this hybrid. Besides confirming the importance of the rootstock as a determinant of the composition of plant microbiomes, our data indicate the relevance of rootstock-selected microbiomes as possible regulators of potassium absorption by V. vinifera.

RevDate: 2018-10-15

Van Assche A, Crauwels S, De Brabanter J, et al (2018)

Characterization of the bacterial community composition in water of drinking water production and distribution systems in Flanders, Belgium.

MicrobiologyOpen [Epub ahead of print].

The quality of drinking water is influenced by its chemical and microbial composition which in turn may be affected by the source water and the different processes applied in drinking water purification systems. In this study, we investigated the bacterial diversity in different water samples from the production and distribution chain of thirteen drinking water production and distribution systems from Flanders (Belgium) that use surface water or groundwater as source water. Water samples were collected over two seasons from the source water, the processed drinking water within the production facility and out of the tap in houses along its distribution network. 454-pyrosequencing of 16S ribosomal RNA gene sequences revealed a total of 1,570 species-level bacterial operational taxonomic units. Strong differences in community composition were found between processed drinking water samples originating from companies that use surface water and other that use groundwater as source water. Proteobacteria was the most abundant phylum in all samples. Yet, several phyla including Actinobacteria were significantly more abundant in surface water while Cyanobacteria were more abundant in surface water and processed water originating from surface water. Gallionella, Acinetobacter, and Pseudomonas were the three most abundant genera detected. Members of the Acinetobacter genus were even found at a relative read abundance of up to 47.5% in processed water samples, indicating a general occurrence of Acinetobacter in drinking water (systems).

RevDate: 2018-10-15

Liu Y, Qin Q, T Defoirdt (2018)

Does quorum sensing interference affect the fitness of bacterial pathogens in the real world?.

Environmental microbiology [Epub ahead of print].

Many bacterial pathogens rely on quorum sensing to control virulence gene expression. Based on numerous experiments conducted under well-defined conditions, quorum sensing interference is considered as a promising strategy to tackle infections and thus might have the potential to (partially) replace antibiotics. Despite the promising results in well-defined (artificial) laboratory experiments, there still is a lack of knowledge with respect to the impact of quorum sensing interference on the fitness of pathogens in more realistic scenarios, including interactions with a host, the external environment and complex microbial communities. In this paper, we critically evaluate the current knowledge with respect to these three facets of the real world that can affect fitness of quorum sensing bacterial pathogens. We argue that further research is needed in order to determine how these factors interplay with quorum sensing and to what extent they can influence the selective pressure that might be exerted by quorum sensing interference (and thus determine the risk of resistance development against quorum sensing interference). This kind of information is indispensable in order to optimize quorum sensing interference-based therapeutic strategies. This article is protected by copyright. All rights reserved.

RevDate: 2018-10-14

Mania I, Gorra R, Colombo N, et al (2018)

Prokaryotic Diversity and Distribution in Different Habitats of an Alpine Rock Glacier-Pond System.

Microbial ecology pii:10.1007/s00248-018-1272-3 [Epub ahead of print].

Rock glaciers (RG) are assumed to influence the biogeochemistry of downstream ecosystems because of the high ratio of rock:water in those systems, but no studies have considered the effects of a RG inflow on the microbial ecology of sediments in a downstream pond. An alpine RG-pond system, located in the NW Italian Alps has been chosen as a model, and Bacteria and Archaea 16S rRNA genes abundance, distribution and diversity have been assessed by qPCR and Illumina sequencing, coupled with geochemical analyses on sediments collected along a distance gradient from the RG inflow. RG surface material and neighbouring soil have been included in the analysis to better elucidate relationships among different habitats.Our results showed that different habitats harboured different, well-separated microbial assemblages. Across the pond, the main variations in community composition (e.g. Thaumarchaeota and Cyanobacteria relative abundance) and porewater geochemistry (pH, DOC, TDN and NH4+) were not directly linked to RG proximity, but to differences in water depth. Some microbial markers potentially linked to the presence of meltwater inputs from the RG have been recognised, although the RG seems to have a greater influence on the pond microbial communities due to its contribution in terms of sedimentary material.

RevDate: 2018-10-23

Sen A, Saha R, Sivakumar K, et al (2018)

Inventorizing the modern benthic foraminiferal assemblage from marginal marine environments across the North West coast of Bay of Bengal.

Zootaxa, 4441(2):245-260 pii:zootaxa.4441.2.3.

Modern benthic foraminiferal assemblages are instrumental in providing information regarding changes in relative sea level as well as prevailing environmental conditions in marine environments. Marginal marine environments are coastal environments that are in most cases characterized by high influx of terrestrially originated nutrients. Inventorizing of modern benthic foraminiferal assemblages from such habitats can act as biotic indicators of water quality variations along with any changes in relative sea level. The present study documents the modern benthic foraminiferal assemblage from three major marginal marine habitats located along the North West coast of Bay of Bengal, in the Indian Ocean. Sediment samples for the purpose were thus collected from the Indian Sundarbans Delta, Chilika lagoon and the Gautami Godavari estuarine zone which encompasses the Kakinada bay. A total of 32 species of benthic foraminifera were documented during the study. The present observations were compared with previous reports of benthic foraminiferal diversity from these habitats and exhibited variability.

RevDate: 2018-10-12

Van Geel M, Yu K, Ceulemans T, et al (2018)

Variation in ectomycorrhizal fungal communities associated with Silver linden (Tilia tomentosa) within and across urban areas.

FEMS microbiology ecology pii:5128480 [Epub ahead of print].

Trees in urban areas face harsh environmental conditions. Ectomycorrhizal fungi (EcM) form a symbiosis with many tree species and provide a range of benefits to their host through their extraradical hyphal network. Although our understanding of the environmental drivers and large scale geographical variation of EcM communities in natural ecosystems is growing, our knowledge of EcM communities within and across urban areas is still limited. Here we characterized EcM communities using Illumina miseq sequencing on 175 root samples of the urban tree Tilia tomentosa from three European cities, namely Leuven (Belgium), Strasbourg (France) and Porto (Portugal). We found strong differences in EcM richness and community composition between cities. Soil acidity, organic matter and moisture content were significantly associated with EcM community composition. In agreement, the explained variability in EcM communities was mostly attributed to general soil characteristics, whereas very little variation was explained by city and heavy metal pollution. Overall, our results suggest that EcM communities in urban areas are significantly associated with soil characteristics, while heavy metal pollution and biogeography had little or no impact. These findings deliver new insights into EcM distribution patterns in urban areas and contribute to specific inoculation strategies to improve urban tree vitality.

RevDate: 2018-10-15

Eisenhauer N, JR Powell (2017)

Plant trait effects on soil organisms and functions.

Pedobiologia, 65:1-4.

Global change alters the composition and functioning of ecosystems by creating novel environmental conditions and thereby selecting for specific traits of organisms. Thus, trait-based approaches are promising tools to more mechanistically understand compositional and functional shifts in ecological communities as well as the dependency of response and effect traits upon global change. Such approaches have been particularly successful for the study of plant communities in terrestrial ecosystems. However, given the intimate linkages between aboveground and belowground compartments as well as the significance of plants as integrating organisms across those compartments, the role of plant traits in affecting soils communities has been understudied. This special issue contains empirical studies and reviews of plant trait effects on soil organisms and functions. Based on those contributions, we discuss here plasticity in trait expression, the context-dependency of plant trait effects, time lags in soil biotic responses to trait expression, and limitations of measured plant traits. We conclude that plant trait-based approaches are an important tool to advance soil ecological research, but also identify critical limitations and next steps.

RevDate: 2018-10-16

Cuer CA, Rodrigues RAR, Balieiro FC, et al (2018)

Short-term effect of Eucalyptus plantations on soil microbial communities and soil-atmosphere methane and nitrous oxide exchange.

Scientific reports, 8(1):15133 pii:10.1038/s41598-018-33594-6.

Soil greenhouse gas (GHG) emissions are a significant environmental problem resulting from microbially-mediated nitrogen (N) and carbon (C) cycling. This study aimed to investigate the impact of Eucalyptus plantations on the structure and function of a soil microbial community, and how resulting alterations may be linked to GHG fluxes. We sampled and monitored two adjacent Eucalyptus plantations-a recently logged site that harbored new seedlings and an adult plantation-and compared them to a site hosting native vegetation. We used 16S rRNA gene sequencing and qPCR amplifications of key nitrogen and methane cycle genes to characterize microbial structure and functional gene abundance and compared our data with soil parameters and GHG fluxes. Both microbial community attributes were significantly affected by land use and logging of Eucalyptus plantations. The genes nosZ and archaeal amoA were significantly more abundant in native forest than in either young or old Eucalyptus plantations. Statistical analyses suggest that land use type has a greater impact on microbial community structure and functional gene abundance than Eucalyptus rotation. There was no correlation between GHG fluxes and shifts in microbial community, suggesting that microbial community structure and functional gene abundance are not the main drivers of GHG fluxes in this system.

RevDate: 2018-10-12

Karmakar R, Bindiya S, P Hariprasad (2019)

Convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant.

The Science of the total environment, 650(Pt 1):858-867.

The focus of this work is to study the convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant cultivated on the Yamuna river bank. Forty-one endophytic bacteria (EB) were isolated from green leafy vegetables (GLV's) and were found to be resistant to a wide range of antibiotics (AB) and heavy metals (HM) tested. Further, they showed susceptibility to Quinolones group of antibiotics, and the HM, Cadmium, Chromium, and Mercury. Twenty-seven percent of these bacteria endowed with Class I integron. The probability of co-existence of HM resistance with β‑lactams was higher, whereas quinolones group of AB recorded lesser values. These EB owned a wide array of beneficial traits, through which they improved the plant health under HM and salt stress conditions. Bacterial identity revealed the association of both plant beneficial and human pathogenic bacteria as an endophyte with GLV's. Principal component analysis showed a pattern of convergent evolution irrespective of their origin. In conclusion, under the selection pressure of AB and HM, the susceptible EB population may reduce with time and the resistant native/introduced bacteria might survive. The vertical and horizontal gene transfer between introduced and native bacteria is the crucial factor in enhancing their fitness along with the host plant to survive under abiotic stress conditions.

RevDate: 2018-10-12

Lourenço KS, Rossetto R, Vitti AC, et al (2019)

Strategies to mitigate the nitrous oxide emissions from nitrogen fertilizer applied with organic fertilizers in sugarcane.

The Science of the total environment, 650(Pt 1):1476-1486.

Vinasse is a major byproduct of the sugarcane biofuel industry, recycled in the fields. However, there is evidence that the application of vinasse with mineral nitrogen (N) fertilizers in sugarcane enhances the emission of greenhouse gases (GHGs). Therefore, strategies are needed to decrease the environmental impacts caused by both inputs. We carried out three sugarcane field experiments by applying N fertilizer (ammonium nitrate) with types of vinasses (concentrated-CV and standard-V) in different combinations (vinasses with N fertilizer and vinasses one month before or after mineral N fertilization). The gases nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) were measured in one experiment fertilized in the beginning (fall/winter = dry season) and two experiments fertilized in the end (spring = rainy season) of the harvest season. Sugarcane fields were sinks rather than sources of CH4, while total carbon emitted as CO2 was similar between seasons and treatments. The effect of mineral fertilization and vinasses (CV and V) on N2O emissions was highly dependent on soil moisture (rain events). The N2O-N fertilizer emission factor (EF) varied from 0.07% to 0.51%, whereas the average EF of V and CV were 0.66% and 0.34%, respectively. On average across the three experiments, the combination of vinasse (CV or V) with N fertilizer increased the N2O emissions 2.9-fold compared to that of N fertilizer alone. For CV + N, the EF was 0.94% of the applied N and 0.23% of the ammonium nitrate-N, and for V + N (EF = 0.47%), increased emissions were observed in two out of three experiments. The strategy of anticipating or postponing vinasse application by one month with respect to mineral N reduced the N2O emissions by 51% for CV, but not for V. Therefore, to avoid boosting N2O emissions, we suggest applying vinasses (CV and V) before or after mineral N fertilization.

RevDate: 2018-10-11

Hessler T, Harrison STL, RJ Huddy (2018)

Stratification of microbial communities throughout a biological sulphate reducing up-flow anaerobic packed bed reactor, revealed through 16S metagenomics.

Research in microbiology pii:S0923-2508(18)30139-6 [Epub ahead of print].

Biological sulphate reduction (BSR) is a promising low-cost treatment of acid rock drainage effluents. In this paper, the system performance and microbial ecology of a lactate supplemented BSR up-flow anaerobic packed bed reactor (UAPBR) are evaluated across reactor height and compared to a continuous stirred tank reactor (CSTR). The biomass concentrations of planktonic and biofilm communities were quantified and subsequently characterised by 16S rRNA gene amplicon sequencing. The defined microbial communities were shown to correlate with differing availability of lactate, volatile fatty acids produced from lactate degradation and sulphate concentration. The UAPBR was able to achieve near complete sulphate conversion at a 4-day hydraulic residence time (HRT) at a sulphate feed concentration of 10.41 mM (1 g/L). The high volumetric sulphate reduction rate of 0.184 mM/L.h achieved in the first third of the reactor was attributed to OTUs present in the planktonic and biofilm communities. While the scavenging of sulphate within the final third of the UAPBR was attributed to an acetate oxidising genus of SRB which was not detected in the lactate-fed CSTR. The detailed analyses of the microbial communities throughout the UAPBR and CSTR contribute to the growing understanding of the impact of the microbial communities of BSR reactors on system performance.

RevDate: 2018-10-14

Cassman NA, Lourenço KS, do Carmo JB, et al (2018)

Correction to: Genome-resolved metagenomics of sugarcane vinasse bacteria.

Biotechnology for biofuels, 11:270 pii:1254.

[This corrects the article DOI: 10.1186/s13068-018-1036-9.].

RevDate: 2018-10-10

Ghosh A, P Bhadury (2018)

Exploring biogeographic patterns of bacterioplankton communities across global estuaries.

MicrobiologyOpen [Epub ahead of print].

Estuaries provide an ideal niche to study structure and function of bacterioplankton communities owing to the presence of a multitude of environmental stressors. Bacterioplankton community structures from nine global estuaries were compared to understand their broad-scale biogeographic patterns. Bacterioplankton community structure from four estuaries of Sundarbans, namely Mooriganga, Thakuran, Matla, and Harinbhanga, was elucidated using Illumina sequencing. Bacterioplankton communities from these estuaries were compared against available bacterioplankton sequence data from Columbia, Delaware, Jiulong, Pearl, and Hangzhou estuaries. All nine estuaries were dominated by Proteobacteria. Other abundant phyla included Bacteroidetes, Firmicutes, Acidobacteria, Actinobacteria, Cyanobacteria, Planctomycetes, and Verrucomicrobia. The abundant bacterial phyla showed a ubiquitous presence across the estuaries. At class level, the overwhelming abundance of Gammaproteobacteria in the estuaries of Sundarbans and Columbia estuary clearly stood out amidst high abundance of Alphaproteobacteria observed in the other estuaries. Abundant bacterial families including Rhodobacteriaceae, Shingomonadaceae, Acidobacteriaceae, Vibrionaceae, and Xanthomondaceae also showed ubiquitous presence in the studied estuaries. However, rare taxa including Chloroflexi, Tenericutes, Nitrospirae, and Deinococcus-Thermus showed clear site-specific distribution patterns. Such distribution patterns were also reinstated by nMDS ordination plots. Such clustering patterns could hint toward the potential role of environmental parameters and substrate specificity which could result in distinct bacterioplankton communities at specific sites. The ubiquitous presence of abundant bacterioplankton groups along with their strong correlation with surface water temperature and dissolved nutrient concentrations indicates the role of such environmental parameters in shaping bacterioplankton community structure in estuaries. Overall, studies on biogeographic patters of bacterioplankton communities can provide interesting insights into ecosystem functioning and health of global estuaries.

RevDate: 2018-10-24

Weber Y, Sinninghe Damsté JS, Zopfi J, et al (2018)

Redox-dependent niche differentiation provides evidence for multiple bacterial sources of glycerol tetraether lipids in lakes.

Proceedings of the National Academy of Sciences of the United States of America, 115(43):10926-10931.

Terrestrial paleoclimate archives such as lake sediments are essential for our understanding of the continental climate system and for the modeling of future climate scenarios. However, quantitative proxies for the determination of paleotemperatures are sparse. The relative abundances of certain bacterial lipids, i.e., branched glycerol dialkyl glycerol tetraethers (brGDGTs), respond to changes in environmental temperature, and thus have great potential for climate reconstruction. Their application to lake deposits, however, is hampered by the lack of fundamental knowledge on the ecology of brGDGT-producing microbes in lakes. Here, we show that brGDGTs are synthesized by multiple groups of bacteria thriving under contrasting redox regimes in a deep meromictic Swiss lake (Lake Lugano). This niche partitioning is evidenced by highly distinct brGDGT inventories in oxic vs. anoxic water masses, and corresponding vertical patterns in bacterial 16S rRNA gene abundances, implying that sedimentary brGDGT records are affected by temperature-independent changes in the community composition of their microbial producers. Furthermore, the stable carbon isotope composition (δ13C) of brGDGTs in Lake Lugano and 34 other (peri-)Alpine lakes attests to the widespread heterotrophic incorporation of 13C-depleted, methane-derived biomass at the redox transition zone of mesotrophic to eutrophic lake systems. The brGDGTs produced under such hypoxic/methanotrophic conditions reflect near-bottom water temperatures, and are characterized by comparatively low δ13C values. Depending on climate zone and water depth, lake sediment archives predominated by deeper water/low-13C brGDGTs may provide more reliable records of climate variability than those where brGDGTs derive from terrestrial and/or aquatic sources with distinct temperature imprints.

RevDate: 2018-10-09

Hall M, RG Beiko (2018)

16S rRNA Gene Analysis with QIIME2.

Methods in molecular biology (Clifton, N.J.), 1849:113-129.

Microbial marker-gene sequence data can be used to generate comprehensive taxonomic profiles of the microorganisms present in a given community and for other community diversity analyses. The process of going from raw gene sequences to taxonomic profiles or diversity measures involves a series of data transformations performed by numerous computational tools. This includes tools for sequence quality checking, denoising, taxonomic classification, alignment, and phylogenetic tree building. In this chapter, we demonstrate how the Quantitative Insights Into Microbial Ecology version 2 (QIIME2) software suite can simplify 16S rRNA marker-gene analysis. We walk through an example data set extracted from the guts of bumblebees in order to show how QIIME2 can transform raw sequences into taxonomic bar plots, phylogenetic trees, principal co-ordinates analyses, and other visualizations of microbial diversity.

RevDate: 2018-10-24

García FC, Bestion E, Warfield R, et al (2018)

Changes in temperature alter the relationship between biodiversity and ecosystem functioning.

Proceedings of the National Academy of Sciences of the United States of America, 115(43):10989-10994.

Global warming and the loss of biodiversity through human activities (e.g., land-use change, pollution, invasive species) are two of the most profound threats to the functional integrity of the Earth's ecosystems. These factors are, however, most frequently investigated separately, ignoring the potential for synergistic effects of biodiversity loss and environmental warming on ecosystem functioning. Here we use high-throughput experiments with microbial communities to investigate how changes in temperature affect the relationship between biodiversity and ecosystem functioning. We found that changes in temperature systematically altered the relationship between biodiversity and ecosystem functioning. As temperatures departed from ambient conditions the exponent of the diversity-functioning relationship increased, meaning that more species were required to maintain ecosystem functioning under thermal stress. This key result was driven by two processes linked to variability in the thermal tolerance curves of taxa. First, more diverse communities had a greater chance of including species with thermal traits that enabled them to maintain productivity as temperatures shifted from ambient conditions. Second, we found a pronounced increase in the contribution of complementarity to the net biodiversity effect at high and low temperatures, indicating that changes in species interactions played a critical role in mediating the impacts of temperature change on the relationship between biodiversity and ecosystem functioning. Our results highlight that if biodiversity loss occurs independently of species' thermal tolerance traits, then the additional impacts of environmental warming will result in sharp declines in ecosystem function.

RevDate: 2018-10-09

Ssepuuya G, Wynants E, Verreth C, et al (2019)

Microbial characterisation of the edible grasshopper Ruspolia differens in raw condition after wild-harvesting in Uganda.

Food microbiology, 77:106-117.

This research aimed at establishing the chemical intrinsic properties and the microbial quality of an edible grasshopper Ruspolia differens and the effect of its source (geographical area) in Uganda, trading point, swarming season and plucking on these parameters. The intrinsic properties of the grasshopper can support the growth of a wide variety of microorganisms. High counts of total aerobic microbes, Enterobacteriaceae, lactic acid bacteria, total aerobic spores, and yeasts and moulds were obtained. Metagenetic analyses yielded 1793 Operational Taxonomic Units (OTUs) belonging to 24 phyla. Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria and Proteobacteria were the most abundant phyla, while members of the genera Acinetobacter, Buttiauxella, Lactococcus, Staphylococcus and Undibacterium were the most abundant OTUs. A number of genera harbouring potential pathogens (Acinetobacter, Bacillus, Buttiauxella, Campylobacter, Clostridium, Staphylococcus, Pseudomonas and Neisseria) were identified. The geographical area, trading point, swarming season and plucking significantly influenced microbial counts and bacterial diversity. The high microbial counts predispose R. differens to fast microbial spoilage, while the presence of Clostridium and Campylobacter makes this grasshopper a potential source of food borne diseases. Further research should identify the specific spoilage microorganisms of R. differens and assess the characteristics of this grasshopper that support growth of food pathogens.

RevDate: 2018-10-10

Urra J, Alkorta I, Mijangos I, et al (2018)

Data on links between structural and functional prokaryotic diversity in long-term sewage sludge amended soil.

Data in brief, 20:1787-1796 pii:S2352-3409(18)31101-6.

The application of sewage sludge to agricultural soil induces co-exposure of prokaryotic populations to antibiotics and heavy metals, thus exerting a selection pressure that may lead to the development of antibiotic resistance. Here, soil samples from a long-term factorial field experiment in which sewage sludge was applied to agricultural soil, at different rates (40 and 80 t ha-1) and frequencies (every 1, 2 and 4 years) of application, were studied to assess: (i) the effect of sewage sludge application on prokaryotic community composition, (ii) the links between prokaryotic community composition and antibiotic resistance profiles, and (iii) the links between antibiotic resistance and metal(oid) concentrations in amended soil. We found no significant impact of sewage sludge on prokaryotic community composition. Some antibiotic resistance genes (ARGs) correlated positively with particular prokaryotic taxa, being Gemmatimonadetes the taxon with the greatest number of positive correlations at phylum level. No positive correlation was found between prokaryotic taxa and genes encoding resistance to sulfonamides and FCA. All metal(oid)s showed positive correlations with, at least, one ARG. Metal(oid) concentrations in soil also showed positive correlations with mobile genetic element genes, particularly with the gene tnpA-07. These data provide useful information on the links between soil prokaryotic composition and resistome profiles, and between antibiotic resistance and metal(oid) concentrations, in agricultural soils amended with sewage sludge.

RevDate: 2018-10-10

Purahong W, Wubet T, Lentendu G, et al (2018)

Determinants of Deadwood-Inhabiting Fungal Communities in Temperate Forests: Molecular Evidence From a Large Scale Deadwood Decomposition Experiment.

Frontiers in microbiology, 9:2120.

Despite the important role of wood-inhabiting fungi (WIF) in deadwood decomposition, our knowledge of the factors shaping the dynamics of their species richness and community composition is scarce. This is due to limitations regarding the resolution of classical methods used for characterizing WIF communities and to a lack of well-replicated long-term experiments with sufficient numbers of tree species. Here, we used a large scale experiment with logs of 11 tree species at an early stage of decomposition, distributed across three regions of Germany, to identify the factors shaping WIF community composition and Operational Taxonomic Unit (OTU) richness using next generation sequencing. We found that tree species identity was the most significant factor, corresponding to (P < 0.001) and explaining 10% (representing 48% of the explainable variance) of the overall WIF community composition. The next important group of variables were wood-physicochemical properties, of which wood pH was the only factor that consistently corresponded to WIF community composition. For overall WIF richness patterns, we found that approximately 20% of the total variance was explained by wood N content, location, tree species identity and wood density. It is noteworthy that the importance of determinants of WIF community composition and richness appeared to depend greatly on tree species group (broadleaved vs. coniferous) and it differed between the fungal phyla Ascomycota and Basidiomycota.

RevDate: 2018-10-26

Cipullo S, Negrin I, Claveau L, et al (2019)

Linking bioavailability and toxicity changes of complex chemicals mixture to support decision making for remediation endpoint of contaminated soils.

The Science of the total environment, 650(Pt 2):2150-2163.

A six-month laboratory scale study was carried out to investigate the effect of biochar and compost amendments on complex chemical mixtures of tar, heavy metals and metalloids in two genuine contaminated soils. An integrated approach, where organic and inorganic contaminants bioavailability and distribution changes, along with a range of microbiological indicators and ecotoxicological bioassays, was used to provide multiple lines of evidence to support the risk characterisation and assess the remediation end-point. Both compost and biochar amendment (p = 0.005) as well as incubation time (p = 0.001) significantly affected the total and bioavailable concentrations of the total petroleum hydrocarbons (TPH) in the two soils. Specifically, TPH concentration decreased by 46% and 30% in Soil 1 and Soil 2 amended with compost. These decreases were accompanied by a reduction of 78% (Soil 1) and 6% (Soil 2) of the bioavailable hydrocarbons and the most significant decrease was observed for the medium to long chain aliphatic compounds (EC16-35) and medium molecular weight aromatic compounds (EC16-21). Compost amendment enhanced the degradation of both the aliphatic and aromatic fractions in the two soils, while biochar contributed to lock the hydrocarbons in the contaminated soils. Neither compost nor biochar affected the distribution and behaviour of the heavy metals (HM) and metalloids in the different soil phases, suggesting that the co-presence of heavy metals and metalloids posed a low risk. Strong negative correlations were observed between the bioavailable hydrocarbon fractions and the ecotoxicological assays suggesting that when bioavailable concentrations decreased, the toxicity also decreased. This study showed that adopting a combined diagnostic approach can significantly help to identify optimal remediation strategies and contribute to change the over-conservative nature of the current risk assessments thus reducing the costs associated with remediation endpoint.

RevDate: 2018-10-05

Benucci GMN, Bonito V, G Bonito (2018)

Fungal, Bacterial, and Archaeal Diversity in Soils Beneath Native and Introduced Plants in Fiji, South Pacific.

Microbial ecology pii:10.1007/s00248-018-1266-1 [Epub ahead of print].

The Fiji Islands is an archipelago of more than 330 islands located in the tropics of the South Pacific Ocean. Microbial diversity and biogeography in this region is still not understood. Here, we present the first molecular characterization of fungal, bacterial, and archaeal communities in soils from different habitats within the largest Fijian island, Viti Levu. Soil samples were collected from under native vegetation in maritime-, forest-, stream-, grassland-, and casuarina-dominated habitats, as well as from under the introduced agricultural crops sugarcane, cassava, pine, and mahogany. Soil microbial diversity was analyzed through MiSeq amplicon sequencing of 16S (for prokaryotes), ITS, LSU ribosomal DNA (for fungi). Prokaryotic communities were dominated by Proteobacteria (~ 25%), Acidobacteria (~ 19%), and Actinobacteria (~ 17%), and there were no indicator species associated with particular habitats. ITS and LSU were congruent in β-diversity patterns of fungi, and fungal communities were dominated by Ascomycota (~ 57-64%), followed by Basidiomycota (~ 20-23%) and Mucoromycota (~ 10%) according to ITS, or Chytridiomycota (~ 9%) according to LSU. Indicator species analysis of fungi found statistical associations of Cenococcum, Wilcoxina, and Rhizopogon to Pinus caribaea. We hypothesize these obligate biotrophic fungi were co-introduced with their host plant. Entoloma was statistically associated with grassland soils, and Fusarium and Lecythophora with soils under cassava. Observed richness varied from 65 (casuarina) to 404 OTUs (cassava) for fungi according to ITS region, and from 1268 (pine) to 2931 OTUs (cassava) for bacteria and archaea. A major finding of this research is that nearly 25% of the fungal OTUs are poorly classified, indicative of novel biodiversity in this region. This preliminary survey provides important baseline data on fungal, bacterial, and archaeal diversity and biogeography in the Fiji Islands.

RevDate: 2018-10-05

Peters MJ, Suwannapong G, Pelin A, et al (2018)

Genetic and Genome Analyses Reveal Genetically Distinct Populations of the Bee Pathogen Nosema ceranae from Thailand.

Microbial ecology pii:10.1007/s00248-018-1268-z [Epub ahead of print].

The recent global decline in Western honeybee (Apis mellifera) populations is of great concern for pollination and honey production worldwide. Declining honeybee populations are frequently infected by the microsporidian pathogen Nosema ceranae. This species was originally described in the Asiatic honeybee (Apis cerana), and its identification in global A. mellifera hives could result from a recent host transfer. Recent genome studies have found that global populations of this parasite are polyploid and that humans may have fueled their global expansion. To better understand N. ceranae biology, we investigated its genetic diversity within part of their native range (Thailand) and among different hosts (A. mellifera, A. cerana) using both PCR and genome-based methods. We find that Thai N. ceranae populations share many SNPs with other global populations and appear to be clonal. However, in stark contrast with previous studies, we found that these populations also carry many SNPs not found elsewhere, indicating that these populations have evolved in their current geographic location for some time. Our genome analyses also indicate the potential presence of diploidy within Thai populations of N. ceranae.

RevDate: 2018-10-10

Walker TWN, Kaiser C, Strasser F, et al (2018)

Microbial temperature sensitivity and biomass change explain soil carbon loss with warming.

Nature climate change, 8(10):885-889.

Soil microorganisms control carbon losses from soils to the atmosphere1-3, yet their responses to climate warming are often short-lived and unpredictable4-7. Two mechanisms, microbial acclimation and substrate depletion, have been proposed to explain temporary warming effects on soil microbial activity8-10. However, empirical support for either mechanism is unconvincing. Here we used geothermal temperature gradients (> 50 years of field warming)11 and a short-term experiment to show that microbial activity (gross rates of growth, turnover, respiration and carbon uptake) is intrinsically temperature sensitive and does not acclimate to warming (+ 6 ºC) over weeks or decades. Permanently accelerated microbial activity caused carbon loss from soil. However, soil carbon loss was temporary because substrate depletion reduced microbial biomass and constrained the influence of microbes over the ecosystem. A microbial biogeochemical model12-14 showed that these observations are reproducible through a modest, but permanent, acceleration in microbial physiology. These findings reveal a mechanism by which intrinsic microbial temperature sensitivity and substrate depletion together dictate warming effects on soil carbon loss via their control over microbial biomass. We thus provide a framework for interpreting the links between temperature, microbial activity and soil carbon loss on timescales relevant to Earth's climate system.

RevDate: 2018-10-26

Staley C, MJ Sadowsky (2018)

Practical considerations for sampling and data analysis in contemporary metagenomics-based environmental studies.

Journal of microbiological methods, 154:14-18 pii:S0167-7012(18)30695-X [Epub ahead of print].

Recent advancements in metagenomic-based studies, especially analyses of amplicon-based DNA sequencing targeting taxonomic marker genes, has led to an unprecedented characterization of microbial communities from diverse ecosystems around the world. While originally constrained by a lack of appropriate analytical tools and sequencing depth, new technologies and computational and statistical algorithms have been developed to handle highly dimensional, next-generation sequencing datasets. Both these tools allow for the robust analysis of structural and distributional patterns of microbiota essential for the understanding of microbial ecology and biogeography. Furthermore, consortia of individual laboratories working on large interdisciplinary research programs, like the Human and Earth Microbiome Projects, have developed standardized protocols for DNA extraction, sequencing pipelines, and bioinformatics. These approaches provide large repositories of publicly available data to serve as references for on-going and future, hypothesis-driven studies to better characterize the roles of microbial communities in diverse ecosystems. In this review, we outline the currently available statistical approaches and tools to aid in statistically powered study designs and analyses. Given what is now known about the enormous diversity and variability of the microbial communities in aquatic and terrestrial habitats, we also discuss practical considerations for sample collection. Due to the extensive advances made in the field of metagenomics over the last decade, rigorous, well replicated, hypothesis-driven studies are: 1) needed, 2) now possible, and 3) essential to make best use of sequencing-based technologies to characterize the roles of microbial communities in the structure and function of diverse ecosystems.

RevDate: 2018-10-11

Mehrshad M, Salcher MM, Okazaki Y, et al (2018)

Hidden in plain sight-highly abundant and diverse planktonic freshwater Chloroflexi.

Microbiome, 6(1):176 pii:10.1186/s40168-018-0563-8.

BACKGROUND: Representatives of the phylum Chloroflexi, though reportedly highly abundant in the extensive deep water habitats of both marine (SAR202 up to 30% of total prokaryotes) and freshwater (CL500-11 up to 26% of total prokaryotes), remain uncultivated and uncharacterized. There are few metagenomic studies on marine Chloroflexi representatives, while the pelagic freshwater Chloroflexi community is largely unknown except for a single metagenome-assembled genome of CL500-11.

RESULTS: Here, we provide the first extensive examination of the community composition of this cosmopolitan phylum in a range of pelagic habitats (176 datasets) and highlight the impact of salinity and depth on their phylogenomic composition. Reconstructed genomes (53 in total) provide a perspective on the phylogeny, metabolism, and distribution of three novel classes and two family-level taxa within the phylum Chloroflexi. We unraveled a remarkable genomic diversity of pelagic freshwater Chloroflexi representatives that thrive not only in the hypolimnion as previously suspected, but also in the epilimnion. Our results suggest that the lake hypolimnion provides a globally stable habitat reflected in lower species diversity among hypolimnion-specific CL500-11 and TK10 clusters in distantly related lakes compared to a higher species diversity of the epilimnion-specific SL56 cluster. Cell volume analyses show that the CL500-11 are among the largest prokaryotic cells in the water column of deep lakes and with a biomass to abundance ratio of two they significantly contribute to the deep lake carbon flow. Metabolic insights indicate participation of JG30-KF-CM66 representatives in the global cobalamin production via cobinamide to cobalamin salvage pathway.

CONCLUSIONS: Extending phylogenomic comparisons to brackish and marine habitats suggests salinity as the major influencer of the community composition of the deep-dwelling Chloroflexi in marine (SAR202) and freshwater (CL500-11) habitats as both counterparts thrive in intermediate brackish salinity; however, freshwater habitats harbor the most phylogenetically diverse community of pelagic Chloroflexi representatives that reside both in epi- and hypolimnion.

RevDate: 2018-10-11

Lebre PH, Aliyu H, De Maayer P, et al (2018)

In silico characterization of the global Geobacillus and Parageobacillus secretome.

Microbial cell factories, 17(1):156 pii:10.1186/s12934-018-1005-9.

BACKGROUND: Geobacillus and Parageobacillus are two ecologically diverse thermophilic genera within the phylum Firmicutes. These taxa have long been of biotechnological interest due to their ability to secrete thermostable enzymes and other biomolecules that have direct applications in various industrial and clinical fields. Despite the commercial and industrial interest in these microorganisms, the full scope of the secreted protein, i.e. the secretome, of Geobacillus and Parageobacillus species remains largely unexplored, with most studies focusing on single enzymes. A genome-wide exploration of the global secretome can provide a platform for understanding the extracellular functional "protein cloud" and the roles that secreted proteins play in the survival and adaptation of these biotechnologically relevant organisms.

RESULTS: In the present study, the global secretion profile of 64 Geobacillus and Parageobacillus strains, comprising 772 distinct proteins, was predicted using comparative genomic approaches. Thirty-one of these proteins are shared across all strains used in this study and function in cell-wall/membrane biogenesis as well as transport and metabolism of carbohydrates, amino acids and inorganic ions. An analysis of the clustering patterns of the secretomes of the 64 strains according to shared functional orthology revealed a correlation between the secreted profiles of different strains and their phylogeny, with Geobacillus and Parageobacillus species forming two distinct functional clades.

CONCLUSIONS: The in silico characterization of the global secretome revealed a metabolically diverse set of secreted proteins, which include proteases, glycoside hydrolases, nutrient binding proteins and toxins.

RevDate: 2018-10-04

Lin X, Hetharua B, Lin L, et al (2018)

Mangrove Sediment Microbiome: Adaptive Microbial Assemblages and Their Routed Biogeochemical Processes in Yunxiao Mangrove National Nature Reserve, China.

Microbial ecology pii:10.1007/s00248-018-1261-6 [Epub ahead of print].

Microorganisms play important roles in mangrove ecosystems. However, we know little about the ecological implications of mangrove microbiomes for high productivity and the efficient circulation of elements in mangrove ecosystems. Here, we focused on mangrove sediments located at the Yunxiao National Mangrove Reserve in southeast China, uncovering the mangrove microbiome using the 16S rRNA gene and shotgun metagenome sequencing approaches. Physicochemical assays characterized the Yunxiao mangrove sediments as carbon (C)-rich, sulfur (S)-rich, and nitrogen (N)-limited environment. Then phylogenetic analysis profiling a distinctive microbiome with an unexpected high frequency of Chloroflexi and Nitrospirae appeared to be an adaptive characteristic of microbial structure in S-rich habitat. Metagenome sequencing analysis revealed that the metabolic pathways of N and S cycling at the community-level were routed through ammonification and dissimilatory nitrate reduction to ammonium for N conservation in this N-limited habitat, and dissimilatory sulfate reduction along with polysulfide formation for generating bioavailable S resource avoiding the biotoxicity of sulfide in mangrove sediments. In addition, methane metabolism acted as a bridge to connect C cycling to N and S cycling. Further identification of possible biogeochemical linkers suggested Syntrophobacter, Sulfurovum, Nitrospira, and Anaerolinea potentially drive the coupling of C, N, and S cycling. These results highlighting the adaptive routed metabolism flow, a previously undescribed property of mangrove sediment microbiome, appears to be a defining characteristic of this habitat and may significantly contribute to the high productivity of mangrove ecosystems, which could be used as indicators for the health and biodiversity of mangrove ecosystems.

RevDate: 2018-10-07

El-Chakhtoura J, Saikaly PE, van Loosdrecht MCM, et al (2018)

Impact of Distribution and Network Flushing on the Drinking Water Microbiome.

Frontiers in microbiology, 9:2205.

We sampled the tap water of seven unique, full-scale drinking water distribution systems at different locations as well as the corresponding treatment plant effluents to evaluate the impact of distribution and the potential presence of a core drinking water microbiome. The water was also sampled during network flushing to examine its effect on the microbial ecology. While a core microbiome dominated by Gammaproteobacteria was found using 16S rRNA gene pyrosequencing, an increase in biomass was detected in the networks, especially during flushing. Water age did not significantly impact the microbiology. Irrespective of differences in treatment plants, tap water bacterial communities in the distinct networks converged and highly resembled the flushed water communities. Piping biofilm and sediment communities therefore largely determine the final tap water microbial quality, attenuating the impact of water source and treatment strategy and highlighting the fundamental role of local physicochemical conditions and microbial processes within infrastructure micro-niches.

RevDate: 2018-10-07

Durán P, Tortella G, Viscardi S, et al (2018)

Microbial Community Composition in Take-All Suppressive Soils.

Frontiers in microbiology, 9:2198.

Gaeumannomyces graminis var. tritici (Ggt) is the main soilborne factor that affects wheat production around the world. Recently we reported the occurrence of six suppressive soils in monoculture areas from indigenous "Mapuche" communities, and evidenced that the suppression relied on the biotic component of those soils. Here, we compare the rhizosphere and endosphere microbial community structure (total bacteria, actinomycetes, total fungi, and ascomycetes) of wheat plants grown in suppressive and conducive soils. Our results suggested that Ggt suppression could be mediated mostly by bacterial endophytes, rather than rhizosphere microorganisms, since the community structure was similar in all suppressive soils as compared with conducive. Interestingly, we found that despite the lower incidence of take-all disease in suppressive soils, the Ggt concentration in roots was not significantly reduced in all suppressive soils compared to those growing in conducive soil. Therefore, the disease suppression is not always related to a reduction of the pathogen biomass. Furthermore, we isolated endophytic bacteria from wheat roots growing in suppressive soils. Among them we identified Serratia spp. and Enterobacter spp. able to inhibit Ggt growth in vitro. Since the disease, but not always pathogen amount, was reduced in the suppressive soils, we propose that take all disease suppressiveness is not only related to direct antagonism to the pathogen.

RevDate: 2018-10-07

Boers SA, Prest EI, Taučer-Kapteijn M, et al (2018)

Monitoring of microbial dynamics in a drinking water distribution system using the culture-free, user-friendly, MYcrobiota platform.

Scientific reports, 8(1):14727 pii:10.1038/s41598-018-32987-x.

Drinking water utilities currently rely on a range of microbiological detection techniques to evaluate the quality of their drinking water (DW). However, microbiota profiling using culture-free 16S rRNA gene next-generation sequencing (NGS) provides an opportunity for improved monitoring of the microbial ecology and quality of DW. Here, we evaluated the utility of a previously validated microbiota profiling platform (MYcrobiota) to investigate the microbial dynamics of a full-scale, non-chlorinated DW distribution system (DWDS). In contrast to conventional methods, we observed spatial and temporal bacterial genus changes (expressed as operational taxonomic units - OTUs) within the DWDS. Further, a small subset of bacterial OTUs dominated with abundances that shifted across the length of the DWDS, and were particularly affected by a post-disinfection step. We also found seasonal variation in OTUs within the DWDS and that many OTUs could not be identified, even though MYcrobiota is specifically designed to reduce potential PCR sequencing artefacts. This suggests that our current knowledge about the microbial ecology of DW communities is limited. Our findings demonstrate that the user-friendly MYcrobiota platform facilitates culture-free, standardized microbial dynamics monitoring and has the capacity to facilitate the introduction of microbiota profiling into the management of drinking water quality.

RevDate: 2018-10-03

Sollai M, Villanueva L, Hopmans EC, et al (2018)

A combined lipidomic and 16S rRNA gene amplicon sequencing approach reveals archaeal sources of intact polar lipids in the stratified Black Sea water column.

Geobiology [Epub ahead of print].

Archaea are important players in marine biogeochemical cycles, and their membrane lipids are useful biomarkers in environmental and geobiological studies. However, many archaeal groups remain uncultured and their lipid composition unknown. Here, we aim to expand the knowledge on archaeal lipid biomarkers and determine the potential sources of those lipids in the water column of the euxinic Black Sea. The archaeal community was evaluated by 16S rRNA gene amplicon sequencing and by quantitative PCR. The archaeal intact polar lipids (IPLs) were investigated by ultra-high-pressure liquid chromatography coupled to high-resolution mass spectrometry. Our study revealed both a complex archaeal community and large changes with water depth in the IPL assemblages. In the oxic/upper suboxic waters (<105 m), the archaeal community was dominated by marine group (MG) I Thaumarchaeota, coinciding with a higher relative abundance of hexose phosphohexose crenarchaeol, a known marker for Thaumarchaeota. In the suboxic waters (80-110 m), MGI Nitrosopumilus sp. dominated and produced predominantly monohexose glycerol dibiphytanyl glycerol tetraethers (GDGTs) and hydroxy-GDGTs. Two clades of MGII Euryarchaeota were present in the oxic and upper suboxic zones in much lower abundances, preventing the detection of their specific IPLs. In the deep sulfidic waters (>110 m), archaea belonging to the DPANN Woesearchaeota, Bathyarchaeota, and ANME-1b clades dominated. Correlation analyses suggest that the IPLs GDGT-0, GDGT-1, and GDGT-2 with two phosphatidylglycerol (PG) head groups and archaeol with a PG, phosphatidylethanolamine, and phosphatidylserine head groups were produced by ANME-1b archaea. Bathyarchaeota represented 55% of the archaea in the deeper part of the euxinic zone and likely produces archaeol with phospho-dihexose and hexose-glucuronic acid head groups.

RevDate: 2018-10-03

Boixel AL, Delestre G, Legeay J, et al (2018)

Phenotyping Thermal Responses of Yeasts and Yeast-like Microorganisms at the Individual and Population Levels: Proof-of-Concept, Development and Application of an Experimental Framework to a Plant Pathogen.

Microbial ecology pii:10.1007/s00248-018-1253-6 [Epub ahead of print].

Deciphering the responses of microbial populations to spatiotemporal changes in their thermal environment is instrumental in improving our understanding of their eco-evolutionary dynamics. Recent studies have shown that current phenotyping protocols do not adequately address all dimensions of phenotype expression. Therefore, these methods can give biased assessments of sensitivity to temperature, leading to misunderstandings concerning the ecological processes underlying thermal plasticity. We describe here a new robust and versatile experimental framework for the accurate investigation of thermal performance and phenotypic diversity in yeasts and yeast-like microorganisms, at the individual and population levels. In addition to proof-of-concept, the application of this framework to the fungal wheat pathogen Zymoseptoria tritici resulted in detailed characterisations for this yeast-like microorganism of (i) the patterns of temperature-dependent changes in performance for four fitness traits; (ii) the consistency in thermal sensitivity rankings of strains between in planta and in vitro growth assessments; (iii) significant interindividual variation in thermal responses, with four principal thermotypes detected in a sample of 66 strains; and (iv) the ecological consequences of this diversity for population-level processes through pairwise competition experiments highlighting temperature-dependent outcomes. These findings extend our knowledge and ability to quantify and categorise the phenotypic heterogeneity of thermal responses. As such, they lay the foundations for further studies elucidating local adaptation patterns and the effects of temperature variations on eco-evolutionary and epidemiological processes.

RevDate: 2018-10-05

Li J, Lin J, Pei C, et al (2018)

Variation of soil bacterial communities along a chronosequence of Eucalyptus plantation.

PeerJ, 6:e5648 pii:5648.

Eucalyptus is harvested for wood and fiber production in many tropical and sub-tropical habitats globally. Plantation has been controversial because of its influence on the surrounding environment, however, the influence of massive Eucalyptus planting on soil microbial communities is unclear. Here we applied high-throughput sequencing of the 16S rRNA gene to assess the microbial community composition and diversity of planting chronosequences, involving two, five and ten years of Eucalyptus plantation, comparing to that of secondary-forest in South China. We found that significant changes in the composition of soil bacteria occurred when the forests were converted from secondary-forest to Eucalyptus. The bacterial community structure was clearly distinct from control and five year samples after Eucalyptus was grown for 2 and 10 years, highlighting the influence of this plantation on local soil microbial communities. These groupings indicated a cycle of impact (2 and 10 year plantations) and low impact (5-year plantations) in this chronosequence of Eucalyptus plantation. Community patterns were underpinned by shifts in soil properties such as pH and phosphorus concentration. Concurrently, key soil taxonomic groups such as Actinobacteria showed abundance shifts, increasing in impacted plantations and decreasing in low impacted samples. Shifts in taxonomy were reflected in a shift in metabolic potential, including pathways for nutrient cycles such as carbon fixation, which changed in abundance over time following Eucalyptus plantation. Combined these results confirm that Eucalyptus plantation can change the community structure and diversity of soil microorganisms with strong implications for land-management and maintaining the health of these ecosystems.

RevDate: 2018-10-07

Quintanilla E, Ramírez-Portilla C, Adu-Oppong B, et al (2018)

Local confinement of disease-related microbiome facilitates recovery of gorgonian sea fans from necrotic-patch disease.

Scientific reports, 8(1):14636 pii:10.1038/s41598-018-33007-8.

Microbiome disruptions triggering disease outbreaks are increasingly threatening corals worldwide. In the Tropical Eastern Pacific, a necrotic-patch disease affecting gorgonian corals (sea fans, Pacifigorgia spp.) has been observed in recent years. However, the composition of the microbiome and its disease-related disruptions remain unknown in these gorgonian corals. Therefore, we analysed 16S rRNA gene amplicons from tissues of healthy colonies (n = 19) and from symptomatic-asymptomatic tissues of diseased colonies (n = 19) of Pacifigorgia cairnsi (Gorgoniidae: Octocorallia) in order to test for disease-related changes in the bacterial microbiome. We found that potential endosymbionts (mostly Endozoicomonas spp.) dominate the core microbiome in healthy colonies. Moreover, healthy tissues differed in community composition and functional profile from those of the symptomatic tissues but did not show differences to asymptomatic tissues of the diseased colonies. A more diverse set of bacteria was observed in symptomatic tissues, together with the decline in abundance of the potential endosymbionts from the healthy core microbiome. Furthermore, according to a comparative taxonomy-based functional profiling, these symptomatic tissues were characterized by the increase in heterotrophic, ammonia oxidizer and dehalogenating bacteria and by the depletion of nitrite and sulphate reducers. Overall, our results suggest that the bacterial microbiome associated with the disease behaves opportunistically and is likely in a state of microbial dysbiosis. We also conclude that the confinement of the disease-related consortium to symptomatic tissues may facilitate colony recovery.

RevDate: 2018-10-02

Renoz F, Pons I, Vanderpoorten A, et al (2018)

Evidence for Gut-Associated Serratia symbiotica in Wild Aphids and Ants Provides New Perspectives on the Evolution of Bacterial Mutualism in Insects.

Microbial ecology pii:10.1007/s00248-018-1265-2 [Epub ahead of print].

Many insects engage in symbiotic associations with diverse assemblages of bacterial symbionts that can deeply impact on their ecology and evolution. The intraspecific variation of symbionts remains poorly assessed while phenotypic effects and transmission behaviors, which are key processes for the persistence and evolution of symbioses, may differ widely depending on the symbiont strains. Serratia symbiotica is one of the most frequent symbiont species in aphids and a valuable model to assess this intraspecific variation since it includes both facultative and obligate symbiotic strains. Despite evidence that some facultative S. symbiotica strains exhibit a free-living capacity, the presence of these strains in wild aphid populations, as well as in insects with which they maintain regular contact, has never been demonstrated. Here, we examined the prevalence, diversity, and tissue tropism of S. symbiotica in wild aphids and associated ants. We found a high occurrence of S. symbiotica infection in ant populations, especially when having tended infected aphid colonies. We also found that the S. symbiotica diversity includes strains found located within the gut of aphids and ants. In the latter, this tissue tropism was found restricted to the proventriculus. Altogether, these findings highlight the extraordinary diversity and versatility of an insect symbiont and suggest the existence of novel routes for symbiont acquisition in insects.

RevDate: 2018-10-02

Blachier F, Beaumont M, Portune KJ, et al (2018)

High-protein diets for weight management: Interactions with the intestinal microbiota and consequences for gut health. A position paper by the my new gut study group.

Clinical nutrition (Edinburgh, Scotland) pii:S0261-5614(18)32454-3 [Epub ahead of print].

BACKGROUND & AIMS: This review examines to what extent high-protein diets (HPD), which may favor body weight loss and improve metabolic outcomes in overweight and obese individuals, may also impact the gut environment, shaping the microbiota and the host-microbe (co)metabolic pathways and products, possibly affecting large intestine mucosa homeostasis.

METHODS: PubMed-referenced publications were analyzed with an emphasis on dietary intervention studies involving human volunteers in order to clarify the beneficial vs. deleterious effects of HPD in terms of both metabolic and gut-related health parameters; taking into account the interactions with the gut microbiota.

RESULTS: HPD generally decrease body weight and improve blood metabolic parameters, but also modify the fecal and urinary contents in various bacterial metabolites and co-metabolites. The effects of HPD on the intestinal microbiota composition appear rather heterogeneous depending on the type of dietary intervention. Recently, HPD consumption was shown to modify the expression of genes playing key roles in homeostatic processes in the rectal mucosa, without evidence of intestinal inflammation. Importantly, the effects of HPD on the gut were dependent on the protein source (i.e. from plant or animal sources), a result which should be considered for further investigations.

CONCLUSION: Although HPD appear to be efficient for weight loss, the effects of HPD on microbiota-derived metabolites and gene expression in the gut raise new questions on the impact of HPD on the large intestine mucosa homeostasis leading the authors to recommend some caution regarding the utilization of HPD, notably in a recurrent and/or long-term ways.

RevDate: 2018-10-22

De Vrieze J, Arends JBA, Verbeeck K, et al (2018)

Interfacing anaerobic digestion with (bio)electrochemical systems: Potentials and challenges.

Water research, 146:244-255 pii:S0043-1354(18)30666-3 [Epub ahead of print].

For over a century, anaerobic digestion has been a key technology in stabilizing organic waste streams, while at the same time enabling the recovery of energy. The anticipated transition to a bio-based economy will only increase the quantity and diversity of organic waste streams to be treated, and, at the same time, increase the demand for additional and effective resource recovery schemes for nutrients and organic matter. The performance of anaerobic digestion can be supported and enhanced by (bio)electrochemical systems in a wide variety of hybrid technologies. Here, the possible benefits of combining anaerobic digestion with (bio)electrochemical systems were reviewed in terms of (1) process monitoring, control, and stabilization, (2) nutrient recovery, (3) effluent polishing, and (4) biogas upgrading. The interaction between microorganisms and electrodes with respect to niche creation is discussed, and the potential impact of this interaction on process performance is evaluated. The strength of combining anaerobic digestion with (bio)electrochemical technologies resides in the complementary character of both technologies, and this perspective was used to distinguish transient trends from schemes with potential for full-scale application. This is supported by an operational costs assessment, showing that the economic potential of combining anaerobic digestion with a (bio)electrochemical system is highly case-specific, and strongly depends on engineering challenges with respect to full-scale applications.

RevDate: 2018-10-21

Tam J, Hoffmann T, Fischer S, et al (2018)

Obesity alters composition and diversity of the oral microbiota in patients with type 2 diabetes mellitus independently of glycemic control.

PloS one, 13(10):e0204724 pii:PONE-D-18-13150.

BACKGROUND AND OBJECTIVE: The involvement of the oral microbiota as a possible link between periodontitis, type 2 diabetes mellitus and obesity is still not well understood. The objective of the study was to investigate if glycemic control and obesity play a role in modulating the composition and diversity of the oral microbial ecology.

MATERIAL AND METHODS: A cohort of patients with type 2 diabetes mellitus (n = 18) was recruited. Participants demonstrating improved glycemic control after 3 months (n = 6) were included in a second examination. A full mouth examination was performed to estimate periodontitis severity followed by sample collection (subgingival plaque and saliva). Generation of large sequence libraries was performed using the high-throughput Illumina MiSeq sequencing platform.

RESULTS: The majority of participants (94.4%, n = 17) presented with moderate or severe forms of periodontitis. Differences in microbial composition and diversity between obese (BMI ≥ 30 kg/m2) and non-obese (BMI < 30 kg/m2) groups were statistically significant. Cross-sectional and longitudinal approaches failed to reveal statistically significant associations between HbA1c level and species composition or diversity.

CONCLUSIONS: Obesity was significantly associated with the oral microbial composition. The impact of glycemic control on oral microbiota, however, could not be assured statistically.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
21454 NE 143rd Street
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E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )