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Bibliography on: Microbial Ecology

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ESP: PubMed Auto Bibliography 08 Mar 2021 at 01:34 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®)

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RevDate: 2021-03-06

Du B, Wang Q, Yang Q, et al (2021)

Responses of bacterial and bacteriophage communities to long-term exposure to antimicrobial agents in wastewater treatment systems.

Journal of hazardous materials, 414:125486 pii:S0304-3894(21)00449-0 [Epub ahead of print].

The occurrence of antibacterial agents has received increasing concern due to their possible threats to human health. However, the effects of antibacterial residues on the evolution and dynamics between bacteria and bacteriophages in wastewater treatment systems have seldom been researched. Especially for phages, little is known about their response to antimicrobial exposure. In this study, two identical anoxic-aerobic wastewater treatment systems were established to evaluate the responses of bacterial and phage communities to long-term exposure to antimicrobial agents. The results indicated simultaneous exposure to combined antimicrobials significantly inhibited (p < 0.05) the abundance of phages and bacteria. Metagenomic sequencing analysis indicated the community of bacteria and phages changed greatly at the genus level due to combined antibacterial exposure. Additionally, long-term exposure to antimicrobial agents promoted the attachment of receptor-binding protein genes to Klebsiella, Escherichia and Salmonella (which were all members of Enterobacteriaceae). Compared to that in the control system, the numbers of receptor-binding protein genes on their possible phages (such as Lambdalikevirus and P2likevirus) were also obviously higher when the microorganisms were exposed to antimicrobials. The results are helpful to understanding the microbial communities and tracking the relationship of phage-bacterial host systems, especially under the pressure of antimicrobial exposure.

RevDate: 2021-03-06

Ghosh A, P Bhadury (2021)

Correction to: Vibrio chemaguriensis sp. nov., from Sundarbans, Bay of Bengal.

RevDate: 2021-03-06

Madoroba E, Magwedere K, Chaora NS, et al (2021)

Microbial Communities of Meat and Meat Products: An Exploratory Analysis of the Product Quality and Safety at Selected Enterprises in South Africa.

Microorganisms, 9(3): pii:microorganisms9030507.

Consumption of food that is contaminated by microorganisms, chemicals, and toxins may lead to significant morbidity and mortality, which has negative socioeconomic and public health implications. Monitoring and surveillance of microbial diversity along the food value chain is a key component for hazard identification and evaluation of potential pathogen risks from farm to the consumer. The aim of this study was to determine the microbial diversity in meat and meat products from different enterprises and meat types in South Africa. Samples (n = 2017) were analyzed for Yersinia enterocolitica, Salmonella species, Listeria monocytogenes, Campylobacter jejuni, Campylobacter coli, Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, and Clostridium botulinum using culture-based methods. PCR was used for confirmation of selected pathogens. Of the 2017 samples analyzed, microbial ecology was assessed for selected subsamples where next generation sequencing had been conducted, followed by the application of computational methods to reconstruct individual genomes from the respective sample (metagenomics). With the exception of Clostridium botulinum, selective culture-dependent methods revealed that samples were contaminated with at least one of the tested foodborne pathogens. The data from metagenomics analysis revealed the presence of diverse bacteria, viruses, and fungi. The analyses provide evidence of diverse and highly variable microbial communities in products of animal origin, which is important for food safety, food labeling, biosecurity, and shelf life limiting spoilage by microorganisms.

RevDate: 2021-03-06

Dumolin C, Peeters C, De Canck E, et al (2021)

Network Analysis Based on Unique Spectral Features Enables an Efficient Selection of Genomically Diverse Operational Isolation Units.

Microorganisms, 9(2): pii:microorganisms9020416.

Culturomics-based bacterial diversity studies benefit from the implementation of MALDI-TOF MS to remove genomically redundant isolates from isolate collections. We previously introduced SPeDE, a novel tool designed to dereplicate spectral datasets at an infraspecific level into operational isolation units (OIUs) based on unique spectral features. However, biological and technical variation may result in methodology-induced differences in MALDI-TOF mass spectra and hence provoke the detection of genomically redundant OIUs. In the present study, we used three datasets to analyze to which extent hierarchical clustering and network analysis allowed to eliminate redundant OIUs obtained through biological and technical sample variation and to describe the diversity within a set of spectra obtained from 134 unknown soil isolates. Overall, network analysis based on unique spectral features in MALDI-TOF mass spectra enabled a superior selection of genomically diverse OIUs compared to hierarchical clustering analysis and provided a better understanding of the inter-OIU relationships.

RevDate: 2021-03-06

Lambrecht E, Coillie EV, Boon N, et al (2021)

Transfer of Antibiotic Resistance Plasmid from Commensal E. coli Towards Human Intestinal Microbiota in the M-SHIME: Effect of E. coli dosis, Human Individual and Antibiotic Use.

Life (Basel, Switzerland), 11(3): pii:life11030192.

Along with (in) direct contact with animals and a contaminated environment, humans are exposed to antibiotic-resistant bacteria by consumption of food. The implications of ingesting antibiotic-resistant commensal bacteria are unknown, as dose-response data on resistance transfer and spreading in our gut is lacking. In this study, transfer of a resistance plasmid (IncF), harbouring several antibiotic resistance genes, from a commensal E. coli strain towards human intestinal microbiota was assessed using a Mucosal Simulator of the Human Intestinal Ecosystem (M-SHIME). More specifically, the effect of the initial E. coli plasmid donor concentration (105 and 107 CFU/meal), antibiotic treatment (cefotaxime) and human individual (n = 6) on plasmid transfer towards lumen coliforms and anaerobes was determined. Transfer of the resistance plasmid to luminal coliforms and anaerobes was observed shortly after the donor strain arrived in the colon and was independent of the ingested dose. Transfer occurred in all six simulated colons and despite their unique microbial community composition, no differences could be detected in antibiotic resistance transfer rates between the simulated human colons. After 72 h, resistant coliform transconjugants levels ranged from 7.6 × 104 to 7.9 × 106 CFUcefotaxime resistant/Ml colon lumen. Presence of the resistance plasmid was confirmed and quantified by PCR and qPCR. Cefotaxime treatment led to a significant reduction (85%) in resistant coliforms, however no significant effect on the total number of cultivable coliforms and anaerobes was observed.

RevDate: 2021-03-06

Vigneron A, Cruaud P, Ducellier F, et al (2021)

Syntrophic Hydrocarbon Degradation in a Decommissioned Off-Shore Subsea Oil Storage Structure.

Microorganisms, 9(2): pii:microorganisms9020356.

Over the last decade, metagenomic studies have revealed the impact of oil production on the microbial ecology of petroleum reservoirs. However, despite their fundamental roles in bioremediation of hydrocarbons, biocorrosion, biofouling and hydrogen sulfide production, oil field and oil production infrastructure microbiomes are poorly explored. Understanding of microbial activities within oil production facilities is therefore crucial for environmental risk mitigation, most notably during decommissioning. The analysis of the planktonic microbial community from the aqueous phase of a subsea oil-storage structure was conducted. This concrete structure was part of the production platform of the Brent oil field (North Sea), which is currently undergoing decommissioning. Quantification and sequencing of microbial 16S rRNA genes, metagenomic analysis and reconstruction of metagenome assembled genomes (MAGs) revealed a unique microbiome, strongly dominated by organisms related to Dethiosulfatibacter and Cloacimonadetes. Consistent with the hydrocarbon content in the aqueous phase of the structure, a strong potential for degradation of low molecular weight aromatic hydrocarbons was apparent in the microbial community. These degradation pathways were associated with taxonomically diverse microorganisms, including the predominant Dethiosulfatibacter and Cloacimonadetes lineages, expanding the list of potential hydrocarbon degraders. Genes associated with direct and indirect interspecies exchanges (multiheme type-C cytochromes, hydrogenases and formate/acetate metabolism) were widespread in the community, suggesting potential syntrophic hydrocarbon degradation processes in the system. Our results illustrate the importance of genomic data for informing decommissioning strategies in marine environments and reveal that hydrocarbon-degrading community composition and metabolisms in man-made marine structures might differ markedly from natural hydrocarbon-rich marine environments.

RevDate: 2021-03-06

De Pessemier B, Grine L, Debaere M, et al (2021)

Gut-Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions.

Microorganisms, 9(2): pii:microorganisms9020353.

The microbiome plays an important role in a wide variety of skin disorders. Not only is the skin microbiome altered, but also surprisingly many skin diseases are accompanied by an altered gut microbiome. The microbiome is a key regulator for the immune system, as it aims to maintain homeostasis by communicating with tissues and organs in a bidirectional manner. Hence, dysbiosis in the skin and/or gut microbiome is associated with an altered immune response, promoting the development of skin diseases, such as atopic dermatitis, psoriasis, acne vulgaris, dandruff, and even skin cancer. Here, we focus on the associations between the microbiome, diet, metabolites, and immune responses in skin pathologies. This review describes an exhaustive list of common skin conditions with associated dysbiosis in the skin microbiome as well as the current body of evidence on gut microbiome dysbiosis, dietary links, and their interplay with skin conditions. An enhanced understanding of the local skin and gut microbiome including the underlying mechanisms is necessary to shed light on the microbial involvement in human skin diseases and to develop new therapeutic approaches.

RevDate: 2021-03-06

Duysburgh C, Van den Abbeele P, Kamil A, et al (2021)

In vitro-in vivo Validation of Stimulatory Effect of Oat Ingredients on Lactobacilli.

Pathogens (Basel, Switzerland), 10(2): pii:pathogens10020235.

The prebiotic activity of a commercially available oat product and a novel oat ingredient, at similar β-glucan loads, was tested using a validated in vitro gut model (M-SHIME®). The novel oat ingredient was tested further at lower β-glucan loads in vitro, while the commercially available oat product was assessed in a randomised, single-blind, placebo-controlled, and cross-over human study. Both approaches focused on healthy individuals with mild hypercholesterolemia. In vitro analysis revealed that both oat products strongly stimulated Lactobacillaceae and Bifidobacteriaceae in the intestinal lumen and the simulated mucus layer, and corresponded with enhanced levels of acetate and lactate with cross-feeding interactions leading to an associated increase in propionate and butyrate production. The in vitro prebiotic activity of the novel oat ingredient remained at lower β-glucan levels, indicating the prebiotic potential of the novel oat product. Finally, the stimulation of Lactobacillus spp. was confirmed during the in vivo trial, where lactobacilli abundance significantly increased in the overall population at the end of the intervention period with the commercially available oat product relative to the control product, indicating the power of in vitro gut models in predicting in vivo response of the microbial community to dietary modulation.

RevDate: 2021-03-06

Ugalde-Salas P, Ramírez C H, Harmand J, et al (2021)

Microbial Interactions as Drivers of a Nitrification Process in a Chemostat.

Bioengineering (Basel, Switzerland), 8(3): pii:bioengineering8030031.

This article deals with the inclusion of microbial ecology measurements such as abundances of operational taxonomic units in bioprocess modelling. The first part presents the mathematical analysis of a model that may be framed within the class of Lotka-Volterra models fitted to experimental data in a chemostat setting where a nitrification process was operated for over 500 days. The limitations and the insights of such an approach are discussed. In the second part, the use of an optimal tracking technique (developed within the framework of control theory) for the integration of data from genetic sequencing in chemostat models is presented. The optimal tracking revisits the data used in the aforementioned chemostat setting. The resulting model is an explanatory model, not a predictive one, it is able to reconstruct the different forms of nitrogen in the reactor by using the abundances of the operational taxonomic units, providing some insights into the growth rate of microbes in a complex community.

RevDate: 2021-03-06

Cipriano MAP, Freitas-Iório RP, Dimitrov MR, et al (2021)

Plant-Growth Endophytic Bacteria Improve Nutrient Use Efficiency and Modulate Foliar N-Metabolites in Sugarcane Seedling.

Microorganisms, 9(3): pii:microorganisms9030479.

Beneficial plant-microbe interactions lead to physiological and biochemical changes that may result in plant-growth promotion. This study evaluated the effect of the interaction between sugarcane and endophytic bacterial strains on plant physiological and biochemical responses under two levels of nitrogen (N) fertilization. Six strains of endophytic bacteria, previously selected as plant growth-promoting bacteria (PGPB), were used to inoculate sugarcane mini stalks, with and without N fertilization. After 45 days, biomass production; shoot nutrient concentrations; foliar polyamine and free amino acid profiles; activities of nitrate reductase and glutamine synthase; and the relative transcript levels of the GS1, GS2, and SHR5 genes in sugarcane leaves were determined. All six endophytic strains promoted sugarcane growth, increasing shoot and root biomass, plant nutritional status, and the use efficiency of most nutrients. The inoculation-induced changes at the biochemical level altered the foliar free amino acid and polyamine profiles, mainly regarding the relative concentrations of citrulline, putrescine, glycine, alanine, glutamate, glutamine, proline, and aspartate. The transcription of GS1, GS2, and SHR5 was higher in the N fertilized seedlings, and almost not altered by endophytic bacterial strains. The endophytic strains promoted sugarcane seedlings growth mainly by improving nutrient efficiency. This improvement could not be explained by their ability to induce the production of amino acid and polyamine composts, or GS1, GS2, and SHR5, showing that complex interactions may be associated with enhancement of the sugarcane seedlings' performance by endophytic bacteria. The strains demonstrated biotechnological potential for sugarcane seedling production.

RevDate: 2021-03-06

Van den Abbeele P, Sprenger N, Ghyselinck J, et al (2021)

A Comparison of the In Vitro Effects of 2'Fucosyllactose and Lactose on the Composition and Activity of Gut Microbiota from Infants and Toddlers.

Nutrients, 13(3): pii:nu13030726.

Because of the recognized health benefits of breast milk, it is recommended as the sole nutrition source during the first 6 months of life. Among the bioactive components are human milk oligosaccharides (HMOs) that exert part of their activity via the gut microbiota. Here, we investigated the gut microbiota fermentation of HMO 2'fucosyllactose (2'-FL), using two in vitro models (48 h fecal incubations and the long-term mucosal simulator of the human intestinal microbial ecosystem [M-SHIME®]) with fecal samples from 3-month-old breastfed (BF) infants as well as 2-3 year old toddlers. The short-term model allowed the screening of five donors for each group and provided supportive data for the M-SHIME® study. A key finding was the strong and immediate increase in the relative abundance of Bifidobacteriaceae following 2'-FL fermentation by both the BF infant and toddler microbiota in the M-SHIME®. At the metabolic level, while decreasing branched-chain fatty acids, 2'-FL strongly increased acetate production together with increases in the health-related propionate and butyrate whilst gas production only mildly increased. Notably, consistently lower gas production was observed with 2'-FL fermentation as compared to lactose, suggesting that reduced discomfort during the dynamic microbiome establishment in early life may be an advantage along with the bifidogenic effect observed.

RevDate: 2021-03-06

Becker AAMJ, Hill KC, P Butaye (2021)

Unraveling the Gut Microbiome of the Invasive Small Indian Mongoose (Urva auropunctata) in the Caribbean.

Microorganisms, 9(3): pii:microorganisms9030465.

Small Indian mongooses (Urva auropunctata) are among the most pervasive predators to disrupt the native ecology on Caribbean islands and are strongly entrenched in their areas of introduction. Few studies, however, have considered the microbial ecology of such biological invasions. In this study, we investigated the gut microbiota of invasive small Indian mongooses in terms of taxonomic diversity and functional potential. To this end, we collected fecal samples from 60 free-roaming mongooses trapped in different vegetation zones on the island Saint Kitts. The core gut microbiome, assessed by 16S rRNA amplicon gene sequencing on the Ion S5TM XL platform, reflects a carnivore-like signature with a dominant abundance of Firmicutes (54.96%), followed by Proteobacteria (13.98%) and Fusobacteria (12.39%), and a relatively minor contribution of Actinobacteria (10.4%) and Bacteroidetes (6.40%). Mongooses trapped at coastal sites exhibited a higher relative abundance of Fusobacterium spp. whereas those trapped in scrubland areas were enriched in Bacteroidetes, but there was no site-specific difference in predicted metabolic properties. Between males and females, beta-diversity was not significantly different and no sex-specific strategies for energy production were observed. However, the relative abundance of Gammaproteobacteria, and more specifically, Enterobacteriaceae, was significantly higher in males. This first description of the microbial profile of small Indian mongooses provides new insights into their bioecology and can serve as a springboard to further elucidating this invasive predator's impact throughout the Caribbean.

RevDate: 2021-03-05

Ranallo RT, Clifford McDonald L, Laufer Halpin A, et al (2021)

The State of Microbiome Science at the Intersection of Infectious Diseases and Antimicrobial Resistance.

The Journal of infectious diseases pii:6154668 [Epub ahead of print].

Along with the rise in modern chronic diseases, ranging from diabetes to asthma, lay the challenges posed by increasing antibiotic resistance resulting in difficult to treat infections, as well as sepsis. An emerging and unifying theme in the pathogenesis of these diverse public health threats is changes in the microbial communities that inhabit multiple body sites. Although there is great promise in exploring the role of these microbial communities in chronic disease pathogenesis, the shorter timeframe of most infectious disease pathogenesis may allow early translation of our basic scientific understanding of microbial ecology and host-microbiota-pathogen interactions. Likely translation avenues include development of preventive strategies, diagnostics, and therapeutics. For example, as basic research related to microbial pathogenesis continues to progress, Clostridioides difficile infection (CDI) is already being addressed clinically through at least two of these three avenues: targeted antibiotic stewardship and treatment of recurrent disease through fecal microbiota transplantation (FMT).

RevDate: 2021-03-05

Fitzgerald RS, Sanderson IR, MJ Claesson (2021)

Paediatric Inflammatory Bowel Disease and its Relationship with the Microbiome.

Microbial ecology [Epub ahead of print].

Paediatric inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the digestive tract, comprising of Crohn's disease (CD), ulcerative colitis (UC), and, where classification is undetermined, inflammatory bowel disease unclassified (IBDU). Paediatric IBD incidence is increasing globally, with prevalence highest in the developed world. Though no specific causative agent has been identified for paediatric IBD, it is believed that a number of factors may contribute to the development of the disease, including genetics and the environment. Another potential component in the development of IBD is the microbiota in the digestive tract, particularly the gut. While the exact role that the microbiome plays in IBD is unclear, many studies acknowledge the complex relationship between the gut bacteria and pathogenesis of IBD. In this review, we look at the increasing number of studies investigating the role the microbiome and other biomes play in paediatric patients with IBD, particularly changes associated with IBD, varying disease states, and therapeutics. The paediatric IBD microbiome is significantly different to that of healthy children, with decreased diversity and differences in bacterial composition (such as a decrease in Firmicutes). Changes in the microbiome relating to various treatments of IBD and disease severity have also been observed in multiple studies. Changes in diversity and composition may also extend to other biomes in paediatric IBD, such as the virome and the mycobiome. Research into biome differences in IBD paediatric patients may help progress our understanding of the aetiology of the disease.

RevDate: 2021-03-05

Cureau N, Threlfall R, Marasini D, et al (2021)

Year, Location, and Variety Impact on Grape-Associated Mycobiota of Arkansas-Grown Wine Grapes for Wine Production.

Microbial ecology [Epub ahead of print].

Wine grape berries (Vitis spp.) harbor a wide variety of yeasts and filamentous fungi that impact grapevine health and the winemaking process. Identification of these fungi could be important for controlling and improving wine production. The use of high-throughput sequencing (HTS) strategies has enabled identification and quantification of bacterial and fungal species in vineyards. The aims of this study were to identify mycobiota from Cabernet Sauvignon and Zinfandel (V. vinifera), Carlos and Noble muscadines (V. rotundifolia), Cynthiana (V. aestivalis), and Vignoles hybrid (cross of different Vitis spp.) grapes, and investigate the effect of grape variety, location, and year on grape fungal communities. Grape berries were collected in 2016 and 2017 from four vineyards located in Arkansas. The HTS of the Internal Transcribed Spacer 1 region was used to identify grape indigenous epiphytic and endophytic fungal communities. The predominant genera identified on the Arkansas wine grapes were Uwebraunia, Zymoseptoria, Papiliotrema, Meyerozyma, Filobasidium, and Curvibasidium. Overall, the data suggested that grape fungal community distribution and relative abundance were influenced by grape variety, year, and location, but each was influenced to a different extent. Not only were grape mycobiota influenced by year, variety, and location but also it appeared that communities from the previous year impacted microbial communities the following year. For example, an increase of the mycoparasite Ampelomyces quisqualis was noticed in 2017 on grapes that carried the causal agent of powdery mildew, Erysiphe necator, in 2016, thus, amplifying the importance of vineyard microbiota knowledge for disease management and winemaking.

RevDate: 2021-03-05

Zhou X, Li B, Wei J, et al (2021)

Temperature Influenced the Comammox Community Composition in Drinking Water and Wastewater Treatment Plants.

Microbial ecology [Epub ahead of print].

Nitrification is a pivotal step applied in water engineered systems for nitrogen removal. Temperature variation due to seasonal changes is a great challenge for maintaining nitrogen removal efficiency in water engineered ecosystems by affecting nitrifier activities. Research on the abundance, activity, and metabolic characteristics of nitrifiers can provide information for selecting suitable design parameters to ensure efficient nitrogen removal in different seasons. To date, the temperature-related niche separation of comammox, a newly discovered nitrifier with potential high-growth yield, has been rarely investigated. This study addressed the distribution of comammox and canonical nitrifying guilds in drinking water treatment plants (DWTPs) and wastewater treatment plants (WWTPs) in different seasons. qPCR-based surveys showed that comammox ubiquitously distributed and greatly outnumbered other ammonia-oxidizing prokaryotes in both DWTPs and WWTPs, except in Aug samples from DWTPs, suggesting the potential competitive advantage of AOA in summer. The nitrificans-like comammox and nitrosa-like comammox comprised the majority of the comammox community in DWTPs and WWTPs, respectively, and COD and NH4+ concentrations significantly contributed to the distinct comammox phylotype distribution between DWTPs and WWTPs. The temperature-related distribution pattern of the comammox community was observed at each site. Moreover, the network complex of comammox communities was highest in Dec at all the sites, possibly contributing to the survival of comammox community in low temperature conditions.

RevDate: 2021-03-05

de Assis Costa OY, Meima-Franke M, PLE Bodelier (2021)

Complete and Draft Genome Sequences of Aerobic Methanotrophs Isolated from a Riparian Wetland.

Microbiology resource announcements, 10(9):.

Wetlands are important sources of methane emissions, and the impacts of these emissions can be mitigated by methanotrophic bacteria. The genomes of methanotrophs Methylomonas sp. strain LL1 and Methylosinus sp. strain H3A, as well as Methylocystis sp. strains H4A, H15, H62, and L43, were sequenced and are reported here.

RevDate: 2021-03-05

Petri RM, Aditya S, Humer E, et al (2021)

Effect of an intramammary lipopolysaccharide challenge on the hindgut microbial composition and fermentation of dairy cattle experiencing intermittent subacute ruminal acidosis.

Journal of dairy science pii:S0022-0302(21)00217-4 [Epub ahead of print].

Feeding grain-rich diets often results in subacute ruminal acidosis (SARA), a condition associated with ruminal dysbiosis and systemic inflammation. Yet, the effect of SARA on hindgut microbiota, and whether this condition is aggravated by exogenous immune stimuli, is less understood. Therefore, the aims of this study were to determine the effects of an intermittent high-grain SARA model on the hindgut microbial community, and to evaluate whether the effects of SARA on the fecal microbiome and fermentation were further affected by an intramammary lipopolysaccharide (LPS) challenge. A total of 18 early-lactating Simmental cows were divided into 3 groups (n = 6); 2 were fed a SARA-inducing feeding regimen (60% concentrate), 1 was fed a control (CON) diet (40% concentrate). On d 30, 1 SARA group (SARA-LPS) and the CON group (CON-LPS) were intramammarily challenged with a single dose of 50 µg of LPS from Escherichia coli O26:B6, whereas the remaining 6 SARA cows (SARA-PLA) received a placebo. Using a longitudinal randomized controlled design, with grouping according to parity and days in milk), statistical analysis was performed with baseline measurements used as a covariate in a mixed model procedure. The SARA-inducing feeding challenge resulted in decreased fecal pH and increased butyrate as a proportion of total short-chain fatty acids in the feces. On d 30, SARA-challenged cows had decreased fecal diversity as shown by the Shannon and Chao1 indices and a decrease in the relative abundance of Euryarchaeota and cellulolytic genera, and numerical increases in the relative abundance of several Firmicutes associated with starch and secondary fermentation. The LPS challenge did not affect the fecal pH and short-chain fatty acids, but increased the Chao1 richness index in an interaction with the SARA challenge, and affected the relative abundance of Verrucomicrobia (1.13%), Actinobacteria (0.19%), and Spirochaetes (0.002%), suggesting an effect on the microbial ecology of the hindgut during SARA conditions. In conclusion, the SARA-inducing feeding regimen promoted important microbial changes at d 30, including reduced diversity and evenness compared with CON, whereas the external LPS challenge led to changes in the microbial community without affecting fecal fermentation properties.

RevDate: 2021-03-04

González-Olalla JM, Medina-Sánchez JM, Norici A, et al (2021)

Regulation of Phagotrophy by Prey, Low Nutrients, and Low Light in the Mixotrophic Haptophyte Isochrysis galbana.

Microbial ecology [Epub ahead of print].

Mixotrophy combines autotrophy and phagotrophy in the same cell. However, it is not known to what extent the phagotrophy influences metabolism, cell composition, and growth. In this work, we assess, on the one hand (first test), the role of phagotrophy on the elemental and biochemical composition, cell metabolism, and enzymes related to C, N, and S metabolism of Isochrysis galbana Parke, 1949. On the other hand, we study how a predicted increase of phagotrophy under environmental conditions of low nutrients (second test) and low light (third test) can affect its metabolism and growth. Our results for the first test revealed that bacterivory increased the phosphorous and iron content per cell, accelerating cell division and improving the cell fitness; in addition, the stimulation of some C and N enzymatic routes help to maintain, to some degree, compositional homeostasis. Under nutrient or light scarcity, I. galbana grew more slowly despite greater bacterial consumption, and the activities of key enzymes involved in C, N, and S metabolism changed according to a predominantly phototrophic strategy of nutrition in this alga. Contrary to recent studies, the stimulation of phagotrophy under low nutrient and low irradiance did not imply greater and more efficient C flux.

RevDate: 2021-03-04

Wang H, Li X, Li X, et al (2021)

Community Composition and Co-Occurrence Patterns of Diazotrophs along a Soil Profile in Paddy Fields of Three Soil Types in China.

Microbial ecology [Epub ahead of print].

Diazotrophs play a key role in biological nitrogen (N2) fixation. However, we know little about the distribution of the diazotrophic community along the soil profile in paddy fields. Here, we used Illumina MiSeq sequencing, targeting the nitrogenase reductase (nifH) gene, to investigate changes with depth (0-100 cm) in the diazotrophic community in paddy soils of three regions (Changshu, Hailun, and Yingtan) in China. The results indicated that most diazotrophs belonged to the phylum Proteobacteria, accounting for 78.05% of the total number of sequences. The diazotrophic diversity was generally highest in the 10-20 cm layer, and then significantly decreased with soil depth. Principal coordinate analysis and PERMANOVA indicated that the diazotrophic community structure was significantly affected by region and soil depth. There were obvious differences in the composition of the diazotrophic community between the topsoil (0-40 cm) and the subsoil (40-100 cm). Anaeromyxobacter, Sideroxydans, Methylomonas, Nostoc, Methanocella, and Methanosaeta were enriched in the topsoil, while Geobacter, Azoarcus, Bradyrhizobium, and Dechloromonas were concentrated in the subsoil. Furthermore, co-occurrence network analysis showed that the diazotrophic network in the topsoil was more complex than that in the subsoil. Distance-based redundancy analysis indicated that soil total C and N content and pH were the main factors influencing the vertical variation in the diazotrophic community. These results highlighted that depth has a great impact on the diazotrophic diversity, community composition, and co-occurrence patterns in paddy soil.

RevDate: 2021-03-04

Ross BN, M Whiteley (2020)

Ignoring social distancing: advances in understanding multi-species bacterial interactions.

Faculty reviews, 9:23.

Almost every ecosystem on this planet is teeming with microbial communities made of diverse bacterial species. At a reductionist view, many of these bacteria form pairwise interactions, but, as the field of view expands, the neighboring organisms and the abiotic environment can play a crucial role in shaping the interactions between species. Over the years, a strong foundation of knowledge has been built on isolated pairwise interactions between bacteria, but now the field is advancing toward understanding how cohabitating bacteria and natural surroundings affect these interactions. Use of bottom-up approaches, piecing communities together, and top-down approaches that deconstruct communities are providing insight on how different species interact. In this review, we highlight how studies are incorporating more complex communities, mimicking the natural environment, and recurring findings such as the importance of cooperation for stability in harsh environments and the impact of bacteria-induced environmental pH shifts. Additionally, we will discuss how omics are being used as a top-down approach to identify previously unknown interspecies bacterial interactions and the challenges of these types of studies for microbial ecology.

RevDate: 2021-03-04

Marinkovic ZS, Vulin C, Acman M, et al (2020)

Observing Nutrient Gradients, Gene Expression and Growth Variation Using the "Yeast Machine" Microfluidic Device.

Bio-protocol, 10(13):e3668 pii:3668.

The natural environment of microbial cells like bacteria and yeast is often a complex community in which growth and internal organization reflect morphogenetic processes and interactions that are dependent on spatial position and time. While most of research is performed in simple homogeneous environments (e.g., bulk liquid cultures), which cannot capture full spatiotemporal community dynamics, studying biofilms or colonies is complex and usually does not give access to the spatiotemporal dynamics at single cell level. Here, we detail a protocol for generation of a microfluidic device, the "yeast machine", with arrays of long monolayers of yeast colonies to advance the global understanding of how intercellular metabolic interactions affect the internal structure of colonies within defined and customizable spatial dimensions. With Saccharomyces cerevisiae as a model yeast system we used the "yeast machine" to demonstrate the emergence of glucose gradients by following expression of fluorescently labelled hexose transporters. We further quantified the expression spatial patterns with intra-colony growth rates and expression of other genes regulated by glucose availability. In addition to this, we showed that gradients of amino acids also form within a colony, potentially opening similar approaches to study spatiotemporal formation of gradients of many other nutrients and metabolic waste products. This approach could be used in the future to decipher the interplay between long-range metabolic interactions, cellular development, and morphogenesis in other same species or more complex multi-species systems at single-cell resolution and timescales relevant to ecology and evolution.

RevDate: 2021-03-04

Graf JS, Schorn S, Kitzinger K, et al (2021)

Anaerobic endosymbiont generates energy for ciliate host by denitrification.

Nature [Epub ahead of print].

Mitochondria are specialized eukaryotic organelles that have a dedicated function in oxygen respiration and energy production. They evolved about 2 billion years ago from a free-living bacterial ancestor (probably an alphaproteobacterium), in a process known as endosymbiosis1,2. Many unicellular eukaryotes have since adapted to life in anoxic habitats and their mitochondria have undergone further reductive evolution3. As a result, obligate anaerobic eukaryotes with mitochondrial remnants derive their energy mostly from fermentation4. Here we describe 'Candidatus Azoamicus ciliaticola', which is an obligate endosymbiont of an anaerobic ciliate and has a dedicated role in respiration and providing energy for its eukaryotic host. 'Candidatus A. ciliaticola' contains a highly reduced 0.29-Mb genome that encodes core genes for central information processing, the electron transport chain, a truncated tricarboxylic acid cycle, ATP generation and iron-sulfur cluster biosynthesis. The genome encodes a respiratory denitrification pathway instead of aerobic terminal oxidases, which enables its host to breathe nitrate instead of oxygen. 'Candidatus A. ciliaticola' and its ciliate host represent an example of a symbiosis that is based on the transfer of energy in the form of ATP, rather than nutrition. This discovery raises the possibility that eukaryotes with mitochondrial remnants may secondarily acquire energy-providing endosymbionts to complement or replace functions of their mitochondria.

RevDate: 2021-03-04

Langdahl BR, Bisp P, K Ingvorsen (1996)

Nitrile hydrolysis by Rhodococcus erythropolis BL1, an acetonitrile-tolerant strain isolated from a marine sediment.

Microbiology (Reading, England), 142(1):145-154.

A number of physiologically different nitrile-hydrolysing bacteria were isolated from coastal marine sediments in Denmark by enrichment culture. One strain, BL1, identified as Rhodococcus erythropolis, grew on acetonitrile as sole carbon and nitrogen source in a defined medium. Growth occurred between 0 and 8% NaCl with an optimum around 2%, thus reflecting the marine origin of the isolate. Intact cells of R. erythropolis BL1 could hydrolyse a large variety of saturated and unsaturated aliphatic nitriles to their corresponding acids. Benzonitrile and benzylcyanide were not hydrolysed, whereas some aromatic compounds containing a -CN group attached to a C3 or C4 aliphatic side chain were accepted as substrates. The substrate spectrum of R. erythropolis BL1 was thus markedly different from those of other Grampositive nitrile-hydrolysing bacteria isolated from non-marine environments. Nitrile hydrolysis during growth and in resting cell suspensions usually occurred without intermediate accumulation of amide outside the cells. Detailed studies, however, showed that nitrile hydrolysis by strain BL1 was due to a nitrile hydratase/amidase enzyme system. Nitrile hydratase activity was found to be inducible whereas amidase activity was constitutive. The amidase activity of cells could, however, be enhanced manyfold by growth in media containing acetamide or acetonitrile. In most cases amides were hydrolysed at a much higher rate than the corresponding nitriles, which explained why amides were rarely detected in the surrounding medium during nitrile hydrolysis. R. erythropolis BL1 exhibited the highest tolerance towards acetonitrile ever reported for a nitrile-hydrolysing bacterium, as demonstrated by its ability to grow exponentially in the presence of 900 mM acetonitrile.

RevDate: 2021-03-04

Rosén S, Sjollema K, Veenhuis M, et al (1997)

A cytoplasmic lectin produced by the fungus Arthrobotrys oligospora functions as a storage protein during saprophytic and parasitic growth.

Microbiology (Reading, England), 143(8):2593-2604.

It was recently shown that the nematode-infecting fungus Arthrobotrys oligospora contains a saline-soluble lectin (designated AOL) that is a member of a novel family of fungal lectins sharing similar primary sequences and binding specificities. During saprophytic growth in liquid cultures, levels of AOL and AOL mRNA were found to vary depending on the growth phase of the mycelium and the carbon/nitrogen (C/N) ratio of the medium. AOL was not detected in young mycelium. In older mycelium (stationary growth phase) grown in media with low C/N ratios (1 or 6), AOL comprised 5-20% of the total amount of saline-soluble proteins present in the mycelium. Neither the lectin nor its transcript was detected in mycelia grown in medium with higher C/N ratios (≥150). Under conditions of nitrogen starvation, AOL was preferentially degraded in relation to the total amount of saline-soluble proteins present in the mycelium. During the infection of nematodes, the level of AOL protein and AOL mRNA increased significantly once the nematodes had been penetrated and digested. Large amounts of AOL accumulated in the trophic hyphae growing inside the nematode as visualized by immunofluorescence microscopy. Later, AOL labelling was detected outside the digested nematodes, preferentially in strands of aggregated hyphae and in newly developed trap cells. Electron microscopy showed that AOL was localized to the cytoplasm and the nucleus of both vegetative mycelium and trap cells, and in the trophic hyphae growing inside the infected nematodes. These results indicate that AOL functions as a storage protein during both saprophytic and parasitic growth.

RevDate: 2021-03-03

Ceola G, Goss-Souza D, Alves J, et al (2021)

Biogeographic Patterns of Arbuscular Mycorrhizal Fungal Communities Along a Land-Use Intensification Gradient in the Subtropical Atlantic Forest Biome.

Microbial ecology [Epub ahead of print].

Information concerning arbuscular mycorrhizal (AM) fungal geographical distribution in tropical and subtropical soils from the Atlantic Forest (a global hotspot of biodiversity) are scarce and often restricted to the evaluation of richness and abundance of AM fungal species at specific ecosystems or local landscapes. In this study, we hypothesized that AM fungal diversity and community composition in subtropical soils would display fundamental differences in their geographical patterns, shaped by spatial distance and land-use change, at local and regional scales. AM fungal community composition was examined by spore-based taxonomic analysis, using soil trap cultures. Acaulospora koskei and Glomus were found as generalists, regardless of mesoregions and land uses. Other Acaulospora species were also found generalists within mesoregions. Land-use change and intensification did not influence AM fungal composition, partially rejecting our first hypothesis. We then calculated the distance-decay of similarities among pairs of AM fungal communities and the distance-decay relationship within and over mesoregions. We also performed the Mantel test and redundancy analysis to discriminate the main environmental drivers of AM fungal diversity and composition turnover. Overall, we found significant distance-decays for all land uses. We also observed a distance-decay relationship within the mesoregion scale (< 104 km) and these changes were correlated mainly to soil type (not land use), with the secondary influence of both total organic carbon and clay contents. AM fungal species distribution presented significant distance-decays, regardless of land uses, which was indicative of dispersal limitation, a stochastic neutral process. Although, we found evidence that, coupled with dispersal limitation, niche differentiation also played a role in structuring AM fungal communities, driven by long-term historical contingencies, as represented by soil type, resulting from different soil origin and mineralogy across mesoregions.

RevDate: 2021-03-03

Salawu-Rotimi A, Lebre PH, Vos HC, et al (2021)

Gone with the Wind: Microbial Communities Associated with Dust from Emissive Farmlands.

Microbial ecology [Epub ahead of print].

Dust is a major vehicle for the dispersal of microorganisms across the globe. While much attention has been focused on microbial dispersal in dust plumes from major natural dust sources, very little is known about the fractionation processes that select for the "dust microbiome." The recent identification of highly emissive, agricultural land dust sources in South Africa has provided the opportunity to study the displacement of microbial communities through dust generation and transport. In this study, we aimed to document the microbial communities that are carried in the dust from one of South Africa's most emissive locations, and to investigate the selective factors that control the partitioning of microbial communities from soil to dust. For this purpose, dust samples were generated at different emission sources using a Portable In-Situ Wind Erosion Lab (PI-SWERL), and the taxonomic composition of the resulting microbiomes was compared with the source soils. Dust emission processes resulted in the clear fractionation of the soil bacterial community, where dust samples were significantly enriched in spore-forming taxa. Conversely, little fractionation was observed in the soil fungal communities, such that the dust fungal fingerprint could be used to identify the source soil. Dust microbiomes were also found to vary according to the emission source, suggesting that land use significantly affected the structure and fractionation of microbial communities transported in dust plumes. In addition, several potential biological allergens of fungal origin were detected in the dust microbiomes, highlighting the potential detrimental effects of dust plumes emitted in South Africa. This study represents the first description of the fractionation of microbial taxa occurring at the source of dust plumes and provides a direct link between land use and its impact on the dust microbiome.

RevDate: 2021-03-03

Chaudhary DK, J Kim (2019)

Experimental Setup for a Diffusion Bioreactor to Isolate Unculturable Soil Bacteria.

Bio-protocol, 9(19):e3388 pii:3388.

Unculturable bacteria are those bacteria which proliferate in their native habitat but unable to grow or thrive in the normal laboratory media and conditions. The molecular techniques have revealed the significance of these uncultured bacteria in terms of their functional diversity and potential to produce secondary metabolites. To achieve these benefits, scientists have attempted to isolate and cultivate unculturable bacteria in the laboratory using transwell plates, optical tweezers, laser microdissection, microbioreactors, and diffusions bioreactors. However, these techniques are still inadequate to resolve the difficulties of cultivating unculturable bacteria. Therefore, it is essential to develop new cultivation method that enables growth of diverse range of bacteria in the laboratory conditions. Diffusion bioreactor is a membrane bound chamber which allows microbes to proliferate in their native environment by providing the excess to naturally occurring nutrients and signaling compounds. This paper presents efficient and reliable protocol to construct a diffusion bioreactor and its utilization to isolate and cultivate unculturable soil bacteria in laboratory.

RevDate: 2021-03-03

Hennessy RC, Stougaard P, S Olsson (2019)

Imaging Gene Expression Dynamics in Pseudomonas fluorescens In5 duringInteractions with the Fungus Fusarium graminearum PH-1.

Bio-protocol, 9(12):e3264 pii:3264.

Genomics, transcriptomics and metabolomics are powerful technologies for studying microbial interactions. The main drawback of these methods is the requirement for destructive sampling. We have established an alternative but complementary technique based on a microplate system combined with promoter fusions for visualizing gene expression in space and time. Here we provide a protocol for measuring spatial and temporal gene expression of a bacterial reporter strain interacting with a fungus on a solid surface.

RevDate: 2021-03-03

Belk AD, Duarte T, Quinn C, et al (2021)

Air versus Water Chilling of Chicken: a Pilot Study of Quality, Shelf-Life, Microbial Ecology, and Economics.

mSystems, 6(2):.

The United States' large-scale poultry meat industry is energy and water intensive, and opportunities may exist to improve sustainability during the broiler chilling process. By USDA regulation, after harvest the internal temperature of the chicken must be reduced to 40°F or less within 16 h to inhibit bacterial growth that would otherwise compromise the safety of the product. This step is accomplished most commonly by water immersion chilling in the United States, while air chilling methods dominate other global markets. A comprehensive understanding of the differences between these chilling methods is lacking. Therefore, we assessed the meat quality, shelf-life, microbial ecology, and techno-economic impacts of chilling methods on chicken broilers in a university meat laboratory setting. We discovered that air chilling methods resulted in superior chicken odor and shelf-life, especially prior to 14 days of dark storage. Moreover, we demonstrated that air chilling resulted in a more diverse microbiome that we hypothesize may delay the dominance of the spoilage organism Pseudomonas Finally, a techno-economic analysis highlighted potential economic advantages to air chilling compared to water chilling in facility locations where water costs are a more significant factor than energy costs.IMPORTANCE As the poultry industry works to become more sustainable and to reduce the volume of food waste, it is critical to consider points in the processing system that can be altered to make the process more efficient. In this study, we demonstrate that the method used during chilling (air versus water chilling) influences the final product microbial community, quality, and physiochemistry. Notably, the use of air chilling appears to delay the bloom of Pseudomonas spp. that are the primary spoilers in packaged meat products. By using air chilling to reduce carcass temperatures instead of water chilling, producers may extend the time until spoilage of the products and, depending on the cost of water in the area, may have economic and sustainability advantages. As a next step, a similar experiment should be done in an industrial setting to confirm these results generated in a small-scale university lab facility.

RevDate: 2021-03-03

Yanuka-Golub K, Dubinsky V, Korenblum E, et al (2021)

Anode Surface Bioaugmentation Enhances Deterministic Biofilm Assembly in Microbial Fuel Cells.

mBio, 12(2):.

Microbial fuel cells (MFCs) generate energy while aiding the biodegradation of waste through the activity of an electroactive mixed biofilm. Metabolic cooperation is essential for MFCs' efficiency, especially during early colonization. Thus, examining specific ecological processes that drive the assembly of anode biofilms is highly important for shortening startup times and improving MFC performance, making this technology cost-effective and sustainable. Here, we use metagenomics to show that bioaugmentation of the anode surface with a taxonomically defined electroactive consortium, dominated by Desulfuromonas, resulted in an extremely rapid current density generation. Conversely, the untreated anode surface resulted in a highly stochastic and slower biofilm assembly. Remarkably, an efficient anode colonization process was obtained only if wastewater was added, leading to a nearly complete replacement of the bioaugmented community by Geobacter lovleyi Although different approaches to improve MFC startup have been investigated, we propose that only the combination of anode bioaugmentation with wastewater inoculation can reduce stochasticity. Such an approach provides the conditions that support the growth of specific newly arriving species that positively support the fast establishment of a highly functional anode biofilm.IMPORTANCE Mixed microbial communities play important roles in treating wastewater, in producing renewable energy, and in the bioremediation of pollutants in contaminated environments. While these processes are well known, especially the community structure and biodiversity, how to efficiently and robustly manage microbial community assembly remains unknown. Moreover, it has been shown that a high degree of temporal variation in microbial community composition and structure often occurs even under identical environmental conditions. This heterogeneity is directly related to stochastic processes involved in microbial community organization, similarly during the initial stages of biofilm formation on surfaces. In this study, we show that anode surface pretreatment alone is not sufficient for a substantial improvement in startup times in microbial fuel cells (MFCs), as previously thought. Rather, we have discovered that the combination of applying a well-known consortium directly on the anode surface together with wastewater (including the bacteria that they contain) is the optimized management scheme. This allowed a selected colonization process by the wastewater species, which improved the functionality relative to that of untreated systems.

RevDate: 2021-02-19
CmpDate: 2021-02-19

Patel D, Shittu TA, Baroncelli R, et al (2021)

Genome Sequence of the Biocontrol Agent Coniothyrium minitans Conio (IMI 134523).

Molecular plant-microbe interactions : MPMI, 34(2):222-225.

Coniothyrium minitans (synonym, Paraphaeosphaeria minitans) is a highly specific mycoparasite of the wide host range crop pathogen Sclerotinia sclerotiorum. The capability of C. minitans to destroy the sclerotia of S. sclerotiorum has been well recognized and it is available as a widely used biocontrol product Contans WG. We present the draft genome sequence of C. minitans Conio (IMI 134523), which has previously been used in extensive studies that formed part of a registration package of the commercial product. This work provides a distinctive resource for further research into the molecular basis of mycoparasitism to harness the biocontrol potential of C. minitans.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

RevDate: 2021-03-02

Pavlovic J, Cavalieri D, Mastromei G, et al (2021)

MinION technology for microbiome sequencing applications for the conservation of cultural heritage.

Microbiological research, 247:126727 pii:S0944-5013(21)00033-1 [Epub ahead of print].

The MinION single-molecule sequencing system has been attracting the attention of the community of microbiologists involved in the conservation of cultural heritage. The use of MinION for the conservation of cultural heritage is extremely recent, but surprisingly the only few applications available have been exploring many different substrates: stone, textiles, paintings and wax. The use of MinION sequencing is mainly used to address the metataxonomy (with special emphasis on non-cultivable microorganisms) with the effort to identify species involved in the degradation of the substrates. In this review, we show the current applications available on different artworks, showing how this technology can be a useful tool for microbiologists and conservators also in light of its low cost and the easy chemistry.

RevDate: 2021-03-02

Li Z, Pan D, Wei G, et al (2021)

Deep sea sediments associated with cold seeps are a subsurface reservoir of viral diversity.

The ISME journal [Epub ahead of print].

In marine ecosystems, viruses exert control on the composition and metabolism of microbial communities, influencing overall biogeochemical cycling. Deep sea sediments associated with cold seeps are known to host taxonomically diverse microbial communities, but little is known about viruses infecting these microorganisms. Here, we probed metagenomes from seven geographically diverse cold seeps across global oceans to assess viral diversity, virus-host interaction, and virus-encoded auxiliary metabolic genes (AMGs). Gene-sharing network comparisons with viruses inhabiting other ecosystems reveal that cold seep sediments harbour considerable unexplored viral diversity. Most cold seep viruses display high degrees of endemism with seep fluid flux being one of the main drivers of viral community composition. In silico predictions linked 14.2% of the viruses to microbial host populations with many belonging to poorly understood candidate bacterial and archaeal phyla. Lysis was predicted to be a predominant viral lifestyle based on lineage-specific virus/host abundance ratios. Metabolic predictions of prokaryotic host genomes and viral AMGs suggest that viruses influence microbial hydrocarbon biodegradation at cold seeps, as well as other carbon, sulfur and nitrogen cycling via virus-induced mortality and/or metabolic augmentation. Overall, these findings reveal the global diversity and biogeography of cold seep viruses and indicate how viruses may manipulate seep microbial ecology and biogeochemistry.

RevDate: 2021-03-01

Rüger L, Feng K, Dumack K, et al (2021)

Assembly Patterns of the Rhizosphere Microbiome Along the Longitudinal Root Axis of Maize (Zea mays L.).

Frontiers in microbiology, 12:614501.

It is by now well proven that different plant species within their specific root systems select for distinct subsets of microbiota from bulk soil - their individual rhizosphere microbiomes. In maize, root growth advances several centimeters each day, with the locations, quality and quantity of rhizodeposition changing. We investigated the assembly of communities of prokaryotes (archaea and bacteria) and their protistan predators (Cercozoa, Rhizaria) along the longitudinal root axis of maize (Zea mays L.). We grew maize plants in an agricultural loamy soil and sampled rhizosphere soil at distinct locations along maize roots. We applied high-throughput sequencing, followed by diversity and network analyses in order to track changes in relative abundances, diversity and co-occurrence of rhizosphere microbiota along the root axis. Apart from a reduction of operational taxonomic unit (OTU) richness and a strong shift in community composition between bulk soil and root tips, patterns of microbial community assembly along maize-roots were more complex than expected. High variation in beta diversity at root tips and the root hair zone indicated substantial randomness of community assembly. Root hair zone communities were characterized by massive co-occurrence of microbial taxa, likely fueled by abundant resource supply from rhizodeposition. Further up the root where lateral roots emerged processes of community assembly appeared to be more deterministic (e.g., through competition and predation). This shift toward significance of deterministic processes was revealed by low variability of beta diversity, changes in network topology, and the appearance of regular phylogenetic co-occurrence patterns in bipartite networks between prokaryotes and their potential protistan predators. Such patterns were strongest in regions with fully developed laterals, suggesting that a consistent rhizosphere microbiome finally assembled. For the targeted improvement of microbiome function, such knowledge on the processes of microbiome assembly on roots and its temporal and spatial variability is crucially important.

RevDate: 2021-02-27

Koroleva E, Mqulwa AZ, Norris-Jones S, et al (2021)

Impact of cigarette butts on bacterial community structure in soil.

Environmental science and pollution research international [Epub ahead of print].

Cigarette butts contribute significantly to global pollution present on the planet. The filters found in cigarette butts contain a microplastic, cellulose acetate, as well as toxic metals and metalloids which are responsible for pollution in the environment. Although cigarette butt litter is prevalent in many soils, research on the effects of these cigarette butts is limited. In this study, we used Automated Ribosomal Intergenic Spacer Analysis (ARISA) to generate DNA fingerprints of bacterial communities in soil before and after the addition of cigarette butt leachate treatments. An ICP-MS analysis of the biodegradable and non-biodegradable cigarette butts revealed the presence of various elements: Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zn. The analysis also specified which metals were present at the highest concentrations in the biodegradable and non-biodegradable cigarette butts, and these were, respectively, Al (1,31 g/kg and 2,35 g/kg), Fe (2,03 g/kg and 1,11 g/kg), and Zn (3,18 mg/kg and 15,70 mg/kg). Our results show that biodegradable cigarette butts had a significant effect on bacterial community composition (beta diversity), unlike the non-biodegradable butts. This effect can be attributed to higher concentrations of certain metals and metalloids in the leachate of biodegradable cigarette butts compared to the non-biodegradable ones. Our findings suggest that biodegradable and non-biodegradable cigarette butts can significantly affect bacterial communities in soil as a result of the leaching of significant quantities of certain elements into the surrounding soils.

RevDate: 2021-02-27

Vashistha G, Mungi NA, Lang JW, et al (2021)

Gharial nesting in a reservoir is limited by reduced river flow and by increased bank vegetation.

Scientific reports, 11(1):4805.

The gharial (Gavialis gangeticus Gmelin) is a fish-eating specialist crocodylian, endemic to south Asia, and critically endangered in its few remaining wild localities. A secondary gharial population resides in riverine-reservoir habitat adjacent to the Nepal border, within the Katerniaghat Wildlife Sanctuary (KWS), and nests along a 10 km riverbank of the Girwa River. A natural channel shift in the mainstream Karnali River (upstream in Nepal) has reduced seasonal flow in the Girwa stretch where gharials nest, coincident with a gradual loss of nest sites, which in turn was related to an overall shift to woody vegetation at these sites. To understand how these changes in riparian vegetation on riverbanks were related to gharial nesting, we sampled vegetation at these sites from 2017 to 2019, and derived an Enhanced Vegetation Index (EVI) from LANDSAT 8 satellite data to quantify riverside vegetation from 1988 through 2019. We found that sampled sites transitioned to woody cover, the number of nesting sites declined, and the number of nests were reduced by > 40%. At these sites, after the channel shift, woody vegetation replaced open sites that predominated prior to the channel shift. Our findings indicate that the lack of open riverbanks and the increase in woody vegetation at potential nesting sites threatens the reproductive success of the KWS gharial population. This population persists today in a regulated river ecosystem, and nests in an altered riparian habitat which appears to be increasingly unsuitable for the continued successful recruitment of breeding adults. This second-ranking, critically endangered remnant population may have incurred an "extinction debt" by living in a reservoir that will lead to its eventual extirpation.

RevDate: 2021-02-27

Wang Z, Chen Z, Kowalchuk GA, et al (2021)

Succession of the Resident Soil Microbial Community in Response to Periodic Inoculations.

Applied and environmental microbiology pii:AEM.00046-21 [Epub ahead of print].

To maintain the beneficial effects of microbial inoculants on plant and soil, repeated inoculation represents a promising option. Until now, the impacts of one-off inoculation on the native microbiome have been explored, but it remains unclear how long and to what extent the periodic inoculations would affect the succession of the resident microbiome in bulk soil. Here we examined the dynamic responses of plant growth, soil functions and resident bacterial community in the bulk soil to periodic inoculations of phosphate-solubilizing and N2-fixing bacteria alone or in combination. Compared to single-strain inoculation, co-inoculation better stimulated plant growth and soil nutrients. However, the benefits from inoculants did not increase with repeated inoculations and were not maintained after transplanting to a different site. In response to microbial inoculants, three patterns of shifts in bacterial composition were observed - fold increased, fold decreased, and resilience. The periodic inoculations impacted the succession course of resident bacterial communities in bulk soil, mainly driven by changes in soil pH and nitrate, resulting in the development of three main cluster types throughout the investigation. The single and mixed inoculants transiently modulated the variation in the resident community in association with soil pH and C/N, but finally the community established and showed resilience to following inoculations. Consequently, the necessity of repeated inoculations should be reconsidered, and while the different microbial inoculants showed distinct impacts on resident microbiome succession, communities ultimately exhibited resilience.IMPORTANCEIntroducing beneficial microbes to the plant-soil system is an environmentally friendly approach to improve crop yield and soil environment. Numerous studies have attempted to reveal the impacts of inoculation on rhizosphere microbiome. However, little is known about the effectiveness of periodic inoculations on soil functioning. In addition, the impact persistence of repeated inoculations on the native community remains unclear. Here, we track the succession traits of resident microbiome in the bulk soil across a growing season and identify the taxa clusters that diversely respond to periodic inoculation. Crucially, we compare the development of resident community composition with and without inoculation, thus providing new insight into understanding the interactions between resident microbes and intruders. Finally, we conclude that initial inoculation plays a more important role in influencing the whole system, and the native microbial community exhibits traits of resilience, but no resistance, to the subsequent inoculations.

RevDate: 2021-02-26

Srivastava A, Mishra S, D Verma (2021)

Characterization of Oral Bacterial Composition of Adult Smokeless Tobacco Users from Healthy Indians Using 16S rDNA Analysis.

Microbial ecology [Epub ahead of print].

The present investigation is aiming to report the oral bacterial composition of smokeless tobacco (SLT) users and to determine the influence of SLT products on the healthy Indian population. With the aid of the V3 hypervariable region of the 16S rRNA gene, a total of 8,080,889 high-quality reads were clustered into 15 phyla and 180 genera in the oral cavity of the SLT users. Comparative analysis revealed a more diverse microbiome where two phyla and sixteen genera were significantly different among the SLT users as compared to the control group (p-value < 0.05). The prevalence of Fusobacteria-, Porphyromonas-, Desulfobulbus-, Enterococcus-, and Parvimonas-like genera among SLT users indicates altered bacterial communities among SLT users. Besides, the depletion of health-compatible bacteria such as Lactobacillus and Haemophilus also suggests poor oral health. Here, the majority of the altered genera belong to Gram-negative anaerobes that have been reported for assisting biofilm formation that leads in the progression of several oral diseases. The PICRUSt analysis further supports the hypothesis where a significant increase in the count of the genes involved in the metabolism of nitrogen, amino acids, and nicotinate/nicotinamide was observed among tobacco chewers. Moreover, this study has a high significance in Indian prospects where the SLT consumers are prevalent but we are deficient in information on their oral microbiome.

RevDate: 2021-02-25

Cho GY, KS Whang (2021)

Sandarakinorhabdus rubra sp. nov., and Sandarakinorhabdus oryzae sp. nov., isolated from oxidized rice paddy soil.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

Three Gram-stain-negative, motile or non-motile, rod-shaped, facultatively aerobic strains, designated MO-4T, NP-34 and NM-18T, were isolated from oxidized rice paddy soil in Chungbuk, Republic of Korea. Colonies were circular and convex with entire margins, red in colour on R2A after 3 days at 30 °C. The three strains grew at pH 5.0-10.0 (optimum, pH 8.0), at 15-45 °C (optimum, 30 °C) and at salinities of 0-1.5 % (w/v) NaCl (optimum, 0.4 % NaCl). The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the three isolates represent members of the genus Sandarakinorhabdus and strains MO-4T and NP-34 were most closely related to Sandarakinorhabdus cyanobacteriorum TH057T (97.7 %) and Sandarakinorhabdus limnophila DSM 17366T (97.1 %). NM-18T showed highest 16S rRNA gene sequence similarities to Sandarakinorhabdus limnophila DSM 17366T (98.7 %) and Sandarakinorhabdus cyanobacteriorum TH057T (96.7 %). Genomic similarities between strains MO-4T and NM-18T and the two type strains of species of the genus Sandarakinorhabdus based on average nucleotide identity and digital DNA-DNA hybridization values were lower than the species delineation thresholds. The major fatty acids were iso-C18 : 1 ω7c and summed feature 3. The DNA G+C contents of strains MO-4T and NM-18T, obtained from genome sequencing data, were 67.6 and 66.6 mol%, respectively. On the basis of these genotypic and phenotypic characteristics, the three strains are assigned to two novel species of the genus Sandarakinorhabdus, for which the names Sandarakinorhabdus rubra sp. nov. (type strain MO-4T =KACC 21378=NBRC 114106) and Sandarakinorhabdus oryzae sp. nov. (type strain NM-18T=KACC 21379=NBRC 113957) are proposed.

RevDate: 2021-02-25

Phillips AA, Speth DR, Miller LG, et al (2021)

Microbial succession and dynamics in meromictic Mono Lake, California.

Geobiology [Epub ahead of print].

Mono Lake is a closed-basin, hypersaline, alkaline lake located in Eastern Sierra Nevada, California, that is dominated by microbial life. This unique ecosystem offers a natural laboratory for probing microbial community responses to environmental change. In 2017, a heavy snowpack and subsequent runoff led Mono Lake to transition from annually mixed (monomictic) to indefinitely stratified (meromictic). We followed microbial succession during this limnological shift, establishing a two-year (2017-2018) water-column time series of geochemical and microbiological data. Following meromictic conditions, anoxia persisted below the chemocline and reduced compounds such as sulfide and ammonium increased in concentration from near 0 to ~400 and ~150 µM, respectively, throughout 2018. We observed significant microbial succession, with trends varying by water depth. In the epilimnion (above the chemocline), aerobic heterotrophs were displaced by phototrophic genera when a large bloom of cyanobacteria appeared in fall 2018. Bacteria in the hypolimnion (below the chemocline) had a delayed, but systematic, response reflecting colonization by sediment "seed bank" communities. Phototrophic sulfide-oxidizing bacteria appeared first in summer 2017, followed by microbes associated with anaerobic fermentation in spring 2018, and eventually sulfate-reducing taxa by fall 2018. This slow shift indicated that multi-year meromixis was required to establish a sulfate-reducing community in Mono Lake, although sulfide oxidizers thrive throughout mixing regimes. The abundant green alga Picocystis remained the dominant primary producer during the meromixis event, abundant throughout the water column including in the hypolimnion despite the absence of light and prevalence of sulfide. Our study adds to the growing literature describing microbial resistance and resilience during lake mixing events related to climatic events and environmental change.

RevDate: 2021-02-25

Benítez-Páez A, Hess AL, Krautbauer S, et al (2021)

Sex, Food, and the Gut Microbiota: Disparate Response to Caloric Restriction Diet with Fibre Supplementation in Women and Men.

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

SCOPE: Dietary-based strategies are regularly explored in controlled clinical trials to provide cost-effective therapies to tackle obesity and its comorbidities. We present a complementary analysis based on a multivariate multi-omics approach of a caloric restriction intervention with fibre supplementation to unveil synergic effects on body weight control, lipid metabolism, and gut microbiota.

METHODS AND RESULTS: We explored faecal BAs and SCFAs, plasma BAs, and faecal shotgun metagenomics on 80 overweight participants of a 12-week caloric restriction clinical trial (-500 kcal/day) randomly allocated into fibre (10 g/day inulin + 10 g/day resistant maltodextrin) or placebo (maltodextrin) supplementation groups. The multi-omic data integration analysis (sparse PLS-DA method) uncovered the benefits of the fibre supplementation and/or the CRD (e.g., increase of Parabacteroides distasonis and faecal propionate), showing sex-specific effects on either adiposity and fasting insulin; effects thought to be linked to changes of specific gut microbiota species, functional genes, and bacterially produced metabolites like SCFAs and secondary BAs.

CONCLUSIONS: Our study has identified diet-microbe-host interactions helping to design personalised interventions. It also suggests that sex perspective should be considered routinely in future studies on dietary interventions efficacy. All in all, we uncovered that our dietary intervention was more beneficial for women than men. This article is protected by copyright. All rights reserved.

RevDate: 2021-02-25

Tang Y, Ma KY, Cheung MK, et al (2021)

Gut Microbiota in Decapod Shrimps: Evidence of Phylosymbiosis.

Microbial ecology [Epub ahead of print].

Gut microbiota have long attracted the interest of scientists due to their profound impact on the well-being of animals. A non-random pattern of microbial assembly that results in a parallelism between host phylogeny and microbial similarity is described as phylosymbiosis. Phylosymbiosis has been consistently observed in different clades of animal hosts, but there have been no studies on crustaceans. In this study, we investigated whether host phylogeny has an impact on the gut microbiota assemblages in decapod shrimps. We examined the gut microbial communities in 20 shrimp species from three families inhabiting distinct environments, using metabarcoding analyses of the V1-V3 hypervariable region of the 16S rRNA gene. Gut microbial communities varied within each shrimp group but were generally dominated by Proteobacteria. A prevalent phylosymbiotic pattern in shrimps was evidenced for the first time by the observations of (1) the distinguishability of microbial communities among species within each group, (2) a significantly lower intraspecific than interspecific gut microbial beta diversity across shrimp groups, (3) topological congruence between host phylogenetic trees and gut microbiota dendrograms, and (4) a correlation between host genetic distances and microbial dissimilarities. Consistent signals of phylosymbiosis were observed across all groups in dendrograms based on the unweighted UniFrac distances at 99% operational taxonomic units (OTUs) level and in Mantel tests based on the weighted UniFrac distances based on 97% OTUs and amplicon sequence variants. Penaeids exhibited phylosymbiosis in most tests, while phylosymbiotic signals in atyids and pandalids were only detected in fewer than half of the tests. A weak phylogenetic signal was detected in the predicted functions of the penaeid gut microbiota. However, the functional diversities of the two caridean groups were not significantly related to host phylogeny. Our observations of a parallelism in the taxonomy of the gut microbiota with host phylogeny for all shrimp groups examined and in the predicted functions for the penaeid shrimps indicate a tight host-microbial relationship during evolution.

RevDate: 2021-02-24

Cho JC (2021)

Omics-based microbiome analysis in microbial ecology: from sequences to information.

Journal of microbiology (Seoul, Korea), 59(3):229-232.

Microbial ecology is the study of microorganisms present in nature. It particularly focuses on microbial interactions with any biota and with surrounding environments. Microbial ecology is entering its golden age with innovative multi-omics methods triggered by next-generation sequencing technologies. However, the extraction of ecologically relevant information from ever-increasing omics data remains one of the most challenging tasks in microbial ecology. This special issue includes 11 review articles that provide an overview of the state of the art of omics-based approaches in the field of microbial ecology, with particular emphasis on the interpretation of omics data, environmental pollution tracking, interactions in microbiomes, and viral ecology.

RevDate: 2021-02-24

Hyun HR, Yoon H, Lyou ES, et al (2021)

Short-Term Legacy Effects of Mercury Contamination on Plant Growth and nifH-Harboring Microbial Community in Rice Paddy Soil.

Microbial ecology [Epub ahead of print].

Methylmercury (MeHg), which is formed in rice paddy soil, exhibits strong neurotoxicity through bioaccumulation in the food chain. A few groups of microorganisms drive both mercury methylation and nitrogen fixation in the rhizosphere. Little is known about how the shifted soil microbial community by Hg contamination affects nitrogen fixation rate and plant growth in paddy soil. Here, we examined how stimulated short-term Hg amendment affects the nitrogen fixing microbial community and influences plant-microbe interactions. Soil was treated with low (0.2 mg/kg) and high (1.1 mg/kg) concentrations of Hg for 4 weeks; then, rice (Oryza sativa) was planted and grown for 12 weeks. The nitrogen-fixation rate and rice growth were measured. The diversity and structure of the microbial community were analyzed by sequencing the nifH gene before and after rice cultivation. Hg treatments significantly decreased the nitrogen fixation rate and dry weight of the rice plants. The structure of the nifH-harboring community was remarkably changed after rice cultivation depending on Hg treatments. Iron- or sulfate-reducing bacteria, including Desulfobacca, Desulfoporosimus, and Geobacter, were observed as legacy response groups; their abundances increased in the soil after Hg treatment. The high abundance of those groups were maintained in control, but the abundance drastically decreased after rice cultivation in the soil treated with Hg, indicating that symbiotic behavior of rice plants changes according to the legacy effects on Hg contamination. These results suggested that Hg contamination can persist in soil microbial communities, affecting their nitrogen-fixation ability and symbiosis with rice plants in paddy soil.

RevDate: 2021-02-22

Zwart MP, Blanc S, Johnson M, et al (2021)

Unresolved advantages of multipartitism in spatially structured environments.

Virus evolution, 7(1):veab004 pii:veab004.

Multipartite viruses have segmented genomes and package each of their genome segments individually into distinct virus particles. Multipartitism is common among plant viruses, but why this apparently costly genome organization and packaging has evolved remains unclear. Recently Zhang and colleagues developed network epidemiology models to study the epidemic spread of multipartite viruses and their distribution over plant and animal hosts (Phys. Rev. Lett. 2019, 123, 138101). In this short commentary, we call into question the relevance of these results because of key model assumptions. First, the model of plant hosts assumes virus transmission only occurs between adjacent plants. This assumption overlooks the basic but imperative fact that most multipartite viruses are transmitted over variable distances by mobile animal vectors, rendering the model results irrelevant to differences between plant and animal hosts. Second, when not all genome segments of a multipartite virus are transmitted to a host, the model assumes an incessant latent infection occurs. This is a bold assumption for which there is no evidence to date, making the relevance of these results to understanding multipartitism questionable.

RevDate: 2021-02-22

Gil J, Andrade-Martínez JS, J Duitama (2021)

Accurate, Efficient and User-Friendly Mutation Calling and Sample Identification for TILLING Experiments.

Frontiers in genetics, 12:624513.

TILLING (Targeting Induced Local Lesions IN Genomes) is a powerful reverse genetics method in plant functional genomics and breeding to identify mutagenized individuals with improved behavior for a trait of interest. Pooled high throughput sequencing (HTS) of the targeted genes allows efficient identification and sample assignment of variants within genes of interest in hundreds of individuals. Although TILLING has been used successfully in different crops and even applied to natural populations, one of the main issues for a successful TILLING experiment is that most currently available bioinformatics tools for variant detection are not designed to identify mutations with low frequencies in pooled samples or to perform sample identification from variants identified in overlapping pools. Our research group maintains the Next Generation Sequencing Experience Platform (NGSEP), an open source solution for analysis of HTS data. In this manuscript, we present three novel components within NGSEP to facilitate the design and analysis of TILLING experiments: a pooled variants detector, a sample identifier from variants detected in overlapping pools and a simulator of TILLING experiments. A new implementation of the NGSEP calling model for variant detection allows accurate detection of low frequency mutations within pools. The samples identifier implements the process to triangulate the mutations called within overlapping pools in order to assign mutations to single individuals whenever possible. Finally, we developed a complete simulator of TILLING experiments to enable benchmarking of different tools and to facilitate the design of experimental alternatives varying the number of pools and individuals per pool. Simulation experiments based on genes from the common bean genome indicate that NGSEP provides similar accuracy and better efficiency than other tools to perform pooled variants detection. To the best of our knowledge, NGSEP is currently the only tool that generates individual assignments of the mutations discovered from the pooled data. We expect that this development will be of great use for different groups implementing TILLING as an alternative for plant breeding and even to research groups performing pooled sequencing for other applications.

RevDate: 2021-02-22

Chang J, Sun Y, Tian L, et al (2021)

The Structure of Rhizosphere Fungal Communities of Wild and Domesticated Rice: Changes in Diversity and Co-occurrence Patterns.

Frontiers in microbiology, 12:610823.

The rhizosphere fungal community affects the ability of crops to acquire nutrients and their susceptibility to pathogen invasion. However, the effects of rice domestication on the diversity and interactions of rhizosphere fungal community still remain largely unknown. Here, internal transcribed spacer amplicon sequencing was used to systematically analyze the structure of rhizosphere fungal communities of wild and domesticated rice. The results showed that domestication increased the alpha diversity indices of the rice rhizosphere fungal community. The changes of alpha diversity index may be associated with the enrichment of Acremonium, Lecythophora, and other specific rare taxa in the rhizosphere of domesticated rice. The co-occurrence network showed that the complexity of wild rice rhizosphere fungal community was higher than that of the domesticated rice rhizosphere fungal community. Arbuscular mycorrhizal fungi (AMF) and soilborne fungi were positively and negatively correlated with more fungi in the wild rice rhizosphere, respectively. For restructuring the rhizomicrobial community of domesticated crops, we hypothesize that microbes that hold positive connections with AMF and negative connections with soilborne fungi can be used as potential sources for bio-inoculation. Our findings provide a scientific basis for reshaping the structure of rhizomicrobial community and furthermore create potential for novel intelligent and sustainable agricultural solutions.

RevDate: 2021-02-22

Patin NV, Dietrich ZA, Stancil A, et al (2021)

Gulf of Mexico blue hole harbors high levels of novel microbial lineages.

The ISME journal [Epub ahead of print].

Exploration of oxygen-depleted marine environments has consistently revealed novel microbial taxa and metabolic capabilities that expand our understanding of microbial evolution and ecology. Marine blue holes are shallow karst formations characterized by low oxygen and high organic matter content. They are logistically challenging to sample, and thus our understanding of their biogeochemistry and microbial ecology is limited. We present a metagenomic and geochemical characterization of Amberjack Hole on the Florida continental shelf (Gulf of Mexico). Dissolved oxygen became depleted at the hole's rim (32 m water depth), remained low but detectable in an intermediate hypoxic zone (40-75 m), and then increased to a secondary peak before falling below detection in the bottom layer (80-110 m), concomitant with increases in nutrients, dissolved iron, and a series of sequentially more reduced sulfur species. Microbial communities in the bottom layer contained heretofore undocumented levels of the recently discovered phylum Woesearchaeota (up to 58% of the community), along with lineages in the bacterial Candidate Phyla Radiation (CPR). Thirty-one high-quality metagenome-assembled genomes (MAGs) showed extensive biochemical capabilities for sulfur and nitrogen cycling, as well as for resisting and respiring arsenic. One uncharacterized gene associated with a CPR lineage differentiated hypoxic from anoxic zone communities. Overall, microbial communities and geochemical profiles were stable across two sampling dates in the spring and fall of 2019. The blue hole habitat is a natural marine laboratory that provides opportunities for sampling taxa with under-characterized but potentially important roles in redox-stratified microbial processes.

RevDate: 2021-02-20

Green EA, Smedley SR, JL Klassen (2021)

North American Fireflies Host Low Bacterial Diversity.

Microbial ecology [Epub ahead of print].

Although there are numerous studies of firefly mating flashes, lantern bioluminescence, and anti-predation lucibufagin metabolites, almost nothing is known about their microbiome. We therefore used 16S rRNA community amplicon sequencing to characterize the gut and body microbiomes of four North American firefly taxa: Ellychnia corrusca, the Photuris versicolor species complex, Pyractomena borealis, and Pyropyga decipiens. These firefly microbiomes all have very low species diversity, often dominated by a single species, and each firefly type has a characteristic microbiome. Although the microbiomes of male and female fireflies did not differ from each other, Ph. versicolor gut and body microbiomes did, with their gut microbiomes being enriched in Pseudomonas and Acinetobacter. Ellychnia corrusca egg and adult microbiomes were unique except for a single egg microbiome that shared a community type with E. corrusca adults, which could suggest microbial transmission from mother to offspring. Mollicutes that had been previously isolated from fireflies were common in our firefly microbiomes. These results set the stage for further research concerning the function and transmission of these bacterial symbionts.

RevDate: 2021-02-19

Tatsumi C, Azuma WA, Ogawa Y, et al (2021)

Nitrogen Availability and Microbial Communities of Canopy Soils in a Large Cercidiphyllum japonicum Tree of a Cool-Temperate Old Growth Forest.

Microbial ecology [Epub ahead of print].

Canopy soils on large trees are important for supporting the lives of many canopy plants, and thereby increasing regional biodiversity. However, because of the less accessibility to canopy soils, there is insufficient knowledge on how canopy soils produce available nitrogen (N) for canopy plants through the activity of canopy soil microbes. Canopy soils usually have different soil properties from ground soils, so we hypothesized that canopy soils would have unique microbial communities compared to ground soils, but still provide available N for canopy plants. Here, we compared soil N availability, including net N mineralization and nitrification rate, and microbial communities between canopy soils (organic soils) collected at various heights of a large Cercidiphyllum japonicum tree and ground soils (organic and mineral soils) in a cool-temperate old-growth forest of Japan. The canopy soils had significantly different N availability (mass-based higher but volume-based lower) and microbial communities from the ground mineral soils. Among organic soils, the height of the soil had an impact on the microbial communities but not on the N availability, which agreed with our hypothesis. Despite the decrease in fungal abundance in the higher soils, the increase in certain components of the cellulose-decomposing fungi and oligotrophic bacteria may contribute to the available N production. Also, the abundance of ammonia-oxidizers did not change with the height, which would be important for the nitrification rate. Our study implied canopy soils could provide N to canopy plants partly through the functional redundancy within different microbial communities and constant population of ammonia-oxidizers.

RevDate: 2021-02-19

Dlamini ST, Jaiswal SK, Mohammed M, et al (2021)

Studies of Phylogeny, Symbiotic Functioning and Ecological Traits of Indigenous Microsymbionts Nodulating Bambara Groundnut (Vigna subterranea L. Verdc) in Eswatini.

Microbial ecology [Epub ahead of print].

Rhizobial microsymbionts of grain legumes are ubiquitous in soils and exhibit a wide range of diversity with respect to colony morphology, genetic variability, biochemical characteristics, and phylogenetic relationships. This study assessed the phylogenetic positions of rhizobial microsymbionts of Bambara groundnut from Eswatini exhibiting variations in morpho-physiology, adaptive characteristics, and N2-fixing efficiency. The isolates' ERIC-PCR profiles revealed the presence of high genetic variation among them. These test isolates also exhibited differences in pH tolerance and IAA production. Multilocus sequence analysis based on the 16S rRNA, atpD, glnII, gyrB, and recA gene sequences of representative test isolates closely aligned them to the type strains of Bradyrhizobium arachidis, B. manausense, B. guangdongense, B. elkanii, and B. pachyrhizi. However, some isolates showed a high divergence from the known reference type strains, indicating that they may represent species yet to be properly characterized and described. Functional characterization in the glasshouse revealed that most of the isolates from the contrasting Agro-ecologies of Eswatini were efficient in N2 fixation, and therefore elicited greater stomatal conductance and photosynthetic rates in the homologous Bambara groundnut. Of the 75 isolates tested, 51% were more effective than the commercial Bradyrhizobium sp. strain CB756, with relative symbiotic effectiveness ranging from 138 to 308%. The findings of this study indicated that the analysis of housekeeping genes and functional traits of Bambara-nodulating microsymbionts can provide a clear view for understanding and predicting rhizobial community structure across environmental gradients.

RevDate: 2021-02-19

Ritter CD, Forster D, Azevedo JAR, et al (2021)

Assessing Biotic and Abiotic Interactions of Microorganisms in Amazonia through Co-Occurrence Networks and DNA Metabarcoding.

Microbial ecology [Epub ahead of print].

Species may co-occur due to responses to similar environmental conditions, biological associations, or simply because of coincident geographical distributions. Disentangling patterns of co-occurrence and potential biotic and abiotic interactions is crucial to understand ecosystem function. Here, we used DNA metabarcoding data from litter and mineral soils collected from a longitudinal transect in Amazonia to explore patterns of co-occurrence. We compared data from different Amazonian habitat types, each with a characteristic biota and environmental conditions. These included non-flooded rainforests (terra-firme), forests seasonally flooded by fertile white waters (várzeas) or by unfertile black waters (igapós), and open areas associated with white sand soil (campinas). We ran co-occurrence network analyses based on null models and Spearman correlation for all samples and for each habitat separately. We found that one third of all operational taxonomic units (OTUs) were bacteria and two thirds were eukaryotes. The resulting networks were nevertheless mostly composed of bacteria, with fewer fungi, protists, and metazoans. Considering the functional traits of the OTUs, there is a combination of metabolism modes including respiration and fermentation for bacteria, and a high frequency of saprotrophic fungi (those that feed on dead organic matter), indicating a high turnover of organic material. The organic carbon and base saturation indices were important in the co-occurrences in Amazonian networks, whereas several other soil properties were important for the co-exclusion. Different habitats had similar network properties with some variation in terms of modularity, probably associated with flooding pulse. We show that Amazonian microorganism communities form highly interconnected co-occurrence and co-exclusion networks, which highlights the importance of complex biotic and abiotic interactions in explaining the outstanding biodiversity of the region.

RevDate: 2021-02-18

Verspecht T, Ghesquière J, Bernaerts K, et al (2021)

Evaluating the intrinsic capacity of oral bacteria to produce hydrogen peroxide (H2O2) in liquid cultures: Interference by bacterial growth media.

Journal of microbiological methods pii:S0167-7012(21)00038-5 [Epub ahead of print].

This work highlights the issue of interference by growth media when measuring bacterial H2O2 production. H2O2 was shown to be stable in phosphate buffered saline (PBS) but not in growth media. The protocol used for evaluating the intrinsic capacity of oral streptococci to produce H2O2 was shown to be reliable.

RevDate: 2021-02-18

Nava-González B, Suazo-Ortuño I, López PB, et al (2021)

Inhibition of Batrachochytrium dendrobatidis Infection by Skin Bacterial Communities in Wild Amphibian Populations.

Microbial ecology [Epub ahead of print].

Skin-associated bacteria are known to inhibit infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd) in amphibians. It has also been postulated that skin-associated bacterial community is related to Bd infection intensity. However, our understanding of host microbial dynamics and their importance in regulating Bd intensity is limited. We analyzed Bd infection and skin-associated bacteria from two amphibian species, the salamander Ambystoma rivulare and the frog Lithobates spectabilis that co-occurred in a tropical high-altitude site in central Mexico. Sixty-three percent of sampled salamander individuals and 80% of frog individuals tested positive for Bd. Overall, we registered 622 skin-associated bacterial genera, from which 73 are known to have Bd inhibitory effects. These inhibitory taxa represented a relative abundance of 50% in relation to total relative bacterial abundance. Our results indicated that, although sharing some bacterial taxa, bacterial community from the skin of both species was different in taxonomic composition and in relative abundance. Pseudomonas spp. and Stenotrophomonas spp. were among the five most abundant bacterial taxa of both species. Both bacterial taxa inhibit Bd infection. We detected that bacterial richness and relative abundance of inhibitory Bd bacteria were negatively related to intensity of Bd infection independent of species and seasons. Despite the high Bd prevalence in both host species, no dead or sick individuals were registered during field surveys. The relatively low levels of Bd load apparently do not compromise survival of host species. Therefore, our results suggested that individuals analyzed were able to survive and thrive under a dynamic relation with enzootic infections of Bd and their microbiota.

RevDate: 2021-02-18

Zhang W, Bahadur A, Sajjad W, et al (2021)

Seasonal Variation in Fungal Community Composition Associated with Tamarix chinensis Roots in the Coastal Saline Soil of Bohai Bay, China.

Microbial ecology [Epub ahead of print].

Coastal salinity typically alters the soil microbial communities, which subsequently affect the biogeochemical cycle of nutrients in the soil. The seasonal variation of the soil fungal communities in the coastal area, closely associated with plant population, is poorly understood. This study provides an insight into the fungal community's variations from autumn to winter and spring to summer at a well-populated area of salt-tolerant Tamarix chinensis and beach. The richness and diversity of fungal community were higher in the spring season and lower in the winter season, as showed by high throughput sequencing of the 18S rRNA gene. Ascomycota was the predominant phylum reported in all samples across the region, and higher difference was reported at order level across the seasonal variations. The redundancy analysis suggested that the abundance and diversity of fungal communities in different seasons are mainly correlated to total organic carbon and total nitrogen. Additionally, the saprotrophic and pathotrophic fungi decreased while symbiotic fungi increased in the autumn season. This study provides a pattern of seasonal variation in fungal community composition that further broadens our limited understanding of how the density of the salt-tolerant T. chinensis population of the coastal saline soil could respond to their seasonal variations.

RevDate: 2021-02-19

Lyu W, Jia H, Deng C, et al (2021)

Zeolite-containing mixture alleviates microbial dysbiosis in dextran sodium sulfate-induced colitis in mice.

Food science & nutrition, 9(2):772-780.

Inflammatory bowel disease (IBD) is a multifactorial immunomodulatory disorder. In relative nosogenesis, gut microbiota has been the focus of research on IBD. In our previous study, we demonstrated the ameliorating effect of zeolite-containing mixture (Hydryeast®, HY) on dextran sodium sulfate (DSS)-induced colitis, through transcriptomics and proteomics. In the present study, we performed further investigation from the perspective of metagenomics using the gut microbiota. C57BL6 mice were provided an AIN-93G basal diet or a 0.8% HY-containing diet, and sterilized tap water for 11 days. Thereafter, colitis was induced by providing 1.5% (w/v) DSS-containing water for 9 days. DNA was extracted from the cecal contents and pooled into libraries in a single Illumina MiSeq run. The resulting sequences were analyzed using Quantitative Insights Into Microbial Ecology (QIIME) software. According to the alterations in the relative abundance of certain bacteria, and the related gene and protein expressions, HY supplementation could improve the gut microbiota composition, ameliorate the degree of inflammation, inhibit the colonic mucosal microbial growth, and, to some extent, promote energy metabolism in the colon compared with the DSS treatment. Thus, we believe that HY may be a candidate to prevent and treat IBD.

RevDate: 2021-02-19

Izabel-Shen D (2021)

Understanding response of microbial communities to saltwater intrusion through microcosms.

Computational and structural biotechnology journal, 19:929-933.

A central pursuit of microbial ecology is to accurately describe and explain the shifts in microbial community composition and function that occur in response to environmental changes. This goal requires a thorough understanding of the individual responses of different species and of the processes guiding the assembly of microbial populations similar in their response traits and corresponding functional traits. These research topics are addressed and synthesized in this Highlights, in four studies applying a trait-based framework to assess how environmental change affected the composition and functional performance of bacterioplankton of natural origin in microcosm experiments. The salinity of many aquatic environments is currently changing, due to climate change and anthropogenic activities. The mechanisms by which salinity influences community assembly, functional redundancy and functional genes involved in nitrogen cycle, and how dispersal modifies community outcome are explored in the four studies. Together, the findings of these case studies demonstrate the feasibility of using novel experiments in combination with integrative analyses of 16S rRNA and meta-'omic' data to address ecological questions. This combined approach has the potential to elucidate both the processes contributing to bacterial community assembly and the possible links between the compositional and functional changes that occur under shifting environmental conditions.

RevDate: 2021-02-19

Wahdan SFM, Heintz-Buschart A, Sansupa C, et al (2021)

Targeting the Active Rhizosphere Microbiome of Trifolium pratense in Grassland Evidences a Stronger-Than-Expected Belowground Biodiversity-Ecosystem Functioning Link.

Frontiers in microbiology, 12:629169.

The relationship between biodiversity and ecosystem functioning (BEF) is a central issue in soil and microbial ecology. To date, most belowground BEF studies focus on the diversity of microbes analyzed by barcoding on total DNA, which targets both active and inactive microbes. This approach creates a bias as it mixes the part of the microbiome currently steering processes that provide actual ecosystem functions with the part not directly involved. Using experimental extensive grasslands under current and future climate, we used the bromodeoxyuridine (BrdU) immunocapture technique combined with pair-end Illumina sequencing to characterize both total and active microbiomes (including both bacteria and fungi) in the rhizosphere of Trifolium pratense. Rhizosphere function was assessed by measuring the activity of three microbial extracellular enzymes (β-glucosidase, N-acetyl-glucosaminidase, and acid phosphatase), which play central roles in the C, N, and P acquisition. We showed that the richness of overall and specific functional groups of active microbes in rhizosphere soil significantly correlated with the measured enzyme activities, while total microbial richness did not. Active microbes of the rhizosphere represented 42.8 and 32.1% of the total bacterial and fungal taxa, respectively, and were taxonomically and functionally diverse. Nitrogen fixing bacteria were highly active in this system with 71% of the total operational taxonomic units (OTUs) assigned to this group detected as active. We found the total and active microbiomes to display different responses to variations in soil physicochemical factors in the grassland, but with some degree of resistance to a manipulation mimicking future climate. Our findings provide critical insights into the role of active microbes in defining soil ecosystem functions in a grassland ecosystem. We demonstrate that the relationship between biodiversity-ecosystem functioning in soil may be stronger than previously thought.

RevDate: 2021-02-18

Gupta S, Shariff M, Chaturvedi G, et al (2021)

Comparative analysis of the alveolar microbiome in COPD, ECOPD, Sarcoidosis, and ILD patients to identify respiratory illnesses specific microbial signatures.

Scientific reports, 11(1):3963.

Studying respiratory illness-specific microbial signatures and their interaction with other micro-residents could provide a better understanding of lung microbial ecology. Each respiratory illness has a specific disease etiology, however, so far no study has revealed disease-specific microbial markers. The present study was designed to determine disease-specific microbial features and their interactions with other residents in chronic obstructive pulmonary diseases (stable and exacerbated), sarcoidosis, and interstitial lung diseases. Broncho-alveolar lavage samples (n = 43) were analyzed by SSU rRNA gene sequencing to study the alveolar microbiome in these diseases. A predominance of Proteobacteria followed by Firmicutes, Bacteroidetes, Actinobacteria, and Fusobacteria was observed in all the disease subsets. Shannon diversity was significantly higher in stable COPD when compared to exacerbated chronic obstructive pulmonary disease (ECOPD) (p = 0.0061), and ILD patient samples (p = 0.037). The lung microbiome of the patients with stable COPD was more diverse in comparison to ECOPD and ILD patients (p < 0.001). Lefse analysis identified 40 disease-differentiating microbial features (LDA score (log10) > 4). Species network analysis indicated a significant correlation (p < 0.05) of diseases specific microbial signature with other lung microbiome members. The current study strengthens the proposed hypothesis that each respiratory illness has unique microbial signatures. These microbial signatures could be used as diagnostic markers to differentiate among various respiratory illnesses.

RevDate: 2021-02-18

Keller CM, Kendra CG, Bruna RE, et al (2021)

Genetic Modification of Sodalis Species by DNA Transduction.

mSphere, 6(1):.

Bacteriophages (phages) are ubiquitous in nature. These viruses play a number of central roles in microbial ecology and evolution by, for instance, promoting horizontal gene transfer (HGT) among bacterial species. The ability of phages to mediate HGT through transduction has been widely exploited as an experimental tool for the genetic study of bacteria. As such, bacteriophage P1 represents a prototypical generalized transducing phage with a broad host range that has been extensively employed in the genetic manipulation of Escherichia coli and a number of other model bacterial species. Here we demonstrate that P1 is capable of infecting, lysogenizing, and promoting transduction in members of the bacterial genus Sodalis, including the maternally inherited insect endosymbiont Sodalis glossinidius While establishing new tools for the genetic study of these bacterial species, our results suggest that P1 may be used to deliver DNA to many Gram-negative endosymbionts in their insect host, thereby circumventing a culturing requirement to genetically manipulate these organisms.IMPORTANCE A large number of economically important insects maintain intimate associations with maternally inherited endosymbiotic bacteria. Due to the inherent nature of these associations, insect endosymbionts cannot be usually isolated in pure culture or genetically manipulated. Here we use a broad-host-range bacteriophage to deliver exogenous DNA to an insect endosymbiont and a closely related free-living species. Our results suggest that broad-host-range bacteriophages can be used to genetically alter insect endosymbionts in their insect host and, as a result, bypass a culturing requirement to genetically alter these bacteria.

RevDate: 2021-02-17

Kleerebezem R, Stouten G, Koehorst J, et al (2021)

Experimental infrastructure requirements for quantitative research on microbial communities.

Current opinion in biotechnology, 67:158-165 pii:S0958-1669(21)00022-7 [Epub ahead of print].

Natural microbial communities are composed of a large diversity of interacting microorganisms, each with a specific role in the functional properties of the ecosystem. The objectives in microbial ecology research are related to identifying, understanding and exploring the role of these different microorganisms. Because of the rapidly increasing power of DNA sequencing and the rapid increase of genomic data, main attention of microbial ecology research shifted from cultivation-oriented studies towards metagenomic studies. Despite these efforts, the direct link between the molecular properties and the measurable changes in the functional performance of the ecosystem is often poorly documented. A quantitative understanding of functional properties in relation to the molecular changes requires effective integration, standardization, and parallelization of experiments. High-resolution functional characterization is a prerequisite for interpretation of changes in metagenomic properties, and will improve our understanding of microbial communities and facilitate their exploration for health and circular economy related objectives.

RevDate: 2021-02-17

Labrador MDM, Doña J, Serrano D, et al (2021)

Correction to: Quantitative Interspecific Approach to the Stylosphere: Patterns of Bacteria and Fungi Abundance on Passerine Bird Feathers.

RevDate: 2021-02-17

Katsoula A, Vasileiadis S, Karamanoli K, et al (2021)

Factors Structuring the Epiphytic Archaeal and Fungal Communities in a Semi-arid Mediterranean Ecosystem.

Microbial ecology [Epub ahead of print].

The phyllosphere microbiome exerts a strong effect on plants' productivity, and its composition is determined by various factors. To date, most phyllosphere studies have focused on bacteria, while fungi and especially archaea have been overlooked. We studied the effects of plant host and season on the abundance and diversity of the epiphytic archaeal and fungal communities in a typical semi-arid Mediterranean ecosystem. We collected leaves in two largely contrasting seasons (summer and winter) from eight perennial species of varying attributes which could be grouped into the following: (i) high-canopy, evergreen sclerophyllοus shrubs with leathery leaves, and low-canopy, either semi-deciduous shrubs or non-woody perennials with non-leathery leaves, and (ii) aromatic and non-aromatic plants. We determined the abundance of epiphytic Crenarchaea, total fungi, Alternaria and Cladosporium (main airborne fungi) via q-PCR and the structure of the epiphytic archaeal and fungal communities via amplicon sequencing. We observed a strong seasonal effect with all microbial groups examined showing higher abundance in summer. Plant host and season were equally important determinants of the composition of the fungal community consisted mostly of Ascomycota, with Hypocreales dominating in winter and Capnodiales and Pleosporales in summer. In contrast, the archaeal community showed plant host driven patterns dominated by the Soil Crenarchaeotic Group (SCG) and Aenigmarchaeota. Plant habit and aromatic nature exhibited filtering effects only on the epiphytic fungal communities. Our study provides a first in-depth analysis of the key determinants shaping the phyllosphere archaeal and fungal communities of a semi-arid Mediterranean ecosystem.

RevDate: 2021-02-16

Taş N, de Jong AE, Li Y, et al (2021)

Metagenomic tools in microbial ecology research.

Current opinion in biotechnology, 67:184-191 pii:S0958-1669(21)00024-0 [Epub ahead of print].

Ability to directly sequence DNA from the environment permanently changed microbial ecology. Here, we review the new insights to microbial life gleaned from the applications of metagenomics, as well as the extensive set of analytical tools that facilitate exploration of diversity and function of complex microbial communities. While metagenomics is shaping our understanding of microbial functions in ecosystems via gene-centric and genome-centric methods, annotating functions, metagenome assembly and binning in heterogeneous samples remains challenging. Development of new analysis and sequencing platforms generating high-throughput long-read sequences and functional screening opportunities will aid in harnessing metagenomes to increase our understanding of microbial taxonomy, function, ecology, and evolution in the environment.

RevDate: 2021-02-16

Luzzi G, Brinks E, Fritsche J, et al (2021)

Effect of reduction of sodium content on the microbial ecology of Edam cheese samples.

AMB Express, 11(1):28.

Sodium intake is a major risk factor for non-communicable diseases. Consequently, reformulation of cheeses such as Edam to contain less sodium may contribute to lowering disease risk. However, sodium is essential for cheese manufacture, influencing starter culture bacteria activity and abundance during fermentation. This study aimed to assess the microbial diversity of reformulated Edam cheese samples with a reduced sodium content using culture-independent technique. The microbial diversity of samples produced using simple sodium reduction, as well as by substituting salt with a mineral salt compound containing potassium, were analysed in comparison to regular control Edam samples during manufacture and the subsequent 6-week ripening period using 16S rDNA metagenomics. In addition, a challenge test using Listeria (List.) innocua as a surrogate species for List. monocytogenes was performed. Reducing sodium content did not influence the microbiological composition of reformulated samples in comparison to that of regular samples. The starter culture bacteria dominated the microbial diversity and no increase in spoilage or potentially pathogenic bacterial growth was detected, including that of List. innocua. From a microbiological perspective, it can be concluded that lowering sodium content in Edam samples without affecting the microbial composition is achievable through simple sodium reduction and through implementation of a mineral salt replacement approach.

RevDate: 2021-02-16

Schorn MA, Verhoeven S, Ridder L, et al (2021)

A community resource for paired genomic and metabolomic data mining.

Nature chemical biology [Epub ahead of print].

RevDate: 2021-02-16

Peixoto RS, Sweet M, Villela HDM, et al (2021)

Coral Probiotics: Premise, Promise, Prospects.

Annual review of animal biosciences, 9:265-288.

The use of Beneficial Microorganisms for Corals (BMCs) has been proposed recently as a tool for the improvement of coral health, with knowledge in this research topic advancing rapidly. BMCs are defined as consortia of microorganisms that contribute to coral health through mechanisms that include (a) promoting coral nutrition and growth, (b) mitigating stress and impacts of toxic compounds, (c) deterring pathogens, and (d) benefiting early life-stage development. Here, we review the current proposed BMC approach and outline the studies that have proven its potential to increase coral resilience to stress. We revisit and expand the list of putative beneficial microorganisms associated with corals and their proposed mechanismsthat facilitate improved host performance. Further, we discuss the caveats and bottlenecks affecting the efficacy of BMCs and close by focusing on the next steps to facilitate application at larger scales that can improve outcomes for corals and reefs globally.

RevDate: 2021-02-15

Zheng R, Wu M, Wang H, et al (2021)

Copper-induced sublethal effects in Bufo gargarizans tadpoles: growth, intestinal histology and microbial alternations.

Ecotoxicology (London, England) [Epub ahead of print].

Copper (Cu) is one of the environmental contaminations which can pose significant risks for organisms. The current study explores the effects of Cu exposure on the growth, intestinal histology and microbial ecology in Bufo gargarizans. The results revealed that 0.5-1 μM Cu exposure induced growth retardation (including reduction of total body length and wet weight) and intestinal histological injury (including disordered enterocyte, changes in the villi and vacuoles) of tadpoles. Also, high-throughput sequencing analysis showed that Cu exposure caused changes in richness, diversity and structure of intestinal microbiota. Moreover, the composition of intestinal microbiota was altered in tadpoles exposed to different concentrations of Cu. At the phylum level, we observed the abundance of proteobacteria was increased, while the abundance of fusobacteria was decreased in the intestinal microbiota of tadpoles exposed to 1 μM Cu. At the genus level, a reduced abundance of kluyvera and aeromonas was observed in the intestinal microbiota of tadpoles under the exposure of 0-0.5 μM Cu. Finally, functional predictions revealed that tadpoles exposed to copper may be at a higher risk of developing metabolic disorders or diseases. Above all, our results will develop a comprehensive view of the Cu exposure in amphibians and will yield a new consideration for sublethal effects of Cu on aquatic organisms.

RevDate: 2021-02-15

George SF, Fierer N, Levy JS, et al (2021)

Antarctic Water Tracks: Microbial Community Responses to Variation in Soil Moisture, pH, and Salinity.

Frontiers in microbiology, 12:616730.

Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (∼5-10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.

RevDate: 2021-02-15

Walker AM, Leigh MB, SL Mincks (2021)

Patterns in Benthic Microbial Community Structure Across Environmental Gradients in the Beaufort Sea Shelf and Slope.

Frontiers in microbiology, 12:581124.

The paradigm of tight pelagic-benthic coupling in the Arctic suggests that current and future fluctuations in sea ice, primary production, and riverine input resulting from global climate change will have major impacts on benthic ecosystems. To understand how these changes will affect benthic ecosystem function, we must characterize diversity, spatial distribution, and community composition for all faunal components. Bacteria and archaea link the biotic and abiotic realms, playing important roles in organic matter (OM) decomposition, biogeochemical cycling, and contaminant degradation, yet sediment microbial communities have rarely been examined in the North American Arctic. Shifts in microbial community structure and composition occur with shifts in OM inputs and contaminant exposure, with implications for shifts in ecological function. Furthermore, the characterization of benthic microbial communities provides a foundation from which to build focused experimental research. We assessed diversity and community structure of benthic prokaryotes in the upper 1 cm of sediments in the southern Beaufort Sea (United States and Canada), and investigated environmental correlates of prokaryotic community structure over a broad spatial scale (spanning 1,229 km) at depths ranging from 17 to 1,200 m. Based on hierarchical clustering, we identified four prokaryotic assemblages from the 85 samples analyzed. Two were largely delineated by the markedly different environmental conditions in shallow shelf vs. upper continental slope sediments. A third assemblage was mainly comprised of operational taxonomic units (OTUs) shared between the shallow shelf and upper slope assemblages. The fourth assemblage corresponded to sediments receiving heavier OM loading, likely resulting in a shallower anoxic layer. These sites may also harbor microbial mats and/or methane seeps. Substructure within these assemblages generally reflected turnover along a longitudinal gradient, which may be related to the quantity and composition of OM deposited to the seafloor; bathymetry and the Mackenzie River were the two major factors influencing prokaryote distribution on this scale. In a broader geographical context, differences in prokaryotic community structure between the Beaufort Sea and Norwegian Arctic suggest that benthic microbes may reflect regional differences in the hydrography, biogeochemistry, and bathymetry of Arctic shelf systems.

RevDate: 2021-02-15

Rain-Franco A, de Moraes GP, S Beier (2020)

Cryopreservation and Resuscitation of Natural Aquatic Prokaryotic Communities.

Frontiers in microbiology, 11:597653.

Experimental reproducibility in aquatic microbial ecology is critical to predict the dynamics of microbial communities. However, controlling the initial composition of naturally occurring microbial communities that will be used as the inoculum in experimental setups is challenging, because a proper method for the preservation of those communities is lacking. To provide a feasible method for preservation and resuscitation of natural aquatic prokaryote assemblages, we developed a cryopreservation procedure applied to natural aquatic prokaryotic communities. We studied the impact of inoculum size, processing time, and storage time on the success of resuscitation. We further assessed the effect of different growth media supplemented with dissolved organic matter (DOM) prepared from naturally occurring microorganisms on the recovery of the initially cryopreserved communities obtained from two sites that have contrasting trophic status and environmental heterogeneity. Our results demonstrated that the variability of the resuscitation process among replicates decreased with increasing inoculum size. The degree of similarity between initial and resuscitated communities was influenced by both the growth medium and origin of the community. We further demonstrated that depending on the inoculum source, 45-72% of the abundant species in the initially natural microbial communities could be detected as viable cells after cryopreservation. Processing time and long-term storage up to 12 months did not significantly influence the community composition after resuscitation. However, based on our results, we recommend keeping handling time to a minimum and ensure identical incubation conditions for repeated resuscitations from cryo-preserved aliquots at different time points. Given our results, we recommend cryopreservation as a promising tool to advance experimental research in the field of microbial ecology.

RevDate: 2021-02-15

Oyserman BO, Cordovez V, Flores SS, et al (2020)

Extracting the GEMs: Genotype, Environment, and Microbiome Interactions Shaping Host Phenotypes.

Frontiers in microbiology, 11:574053.

One of the fundamental tenets of biology is that the phenotype of an organism (Y) is determined by its genotype (G), the environment (E), and their interaction (GE). Quantitative phenotypes can then be modeled as Y = G + E + GE + e, where e is the biological variance. This simple and tractable model has long served as the basis for studies investigating the heritability of traits and decomposing the variability in fitness. The importance and contribution of microbe interactions to a given host phenotype is largely unclear, nor how this relates to the traditional GE model. Here we address this fundamental question and propose an expansion of the original model, referred to as GEM, which explicitly incorporates the contribution of the microbiome (M) to the host phenotype, while maintaining the simplicity and tractability of the original GE model. We show that by keeping host, environment, and microbiome as separate but interacting variables, the GEM model can capture the nuanced ecological interactions between these variables. Finally, we demonstrate with an in vitro experiment how the GEM model can be used to statistically disentangle the relative contributions of each component on specific host phenotypes.

RevDate: 2021-02-14

Petrin S, Orsini M, Mastrorilli E, et al (2021)

Identification and characterization of a spreadable IncI1 plasmid harbouring a blaCTX-M-15 gene in an Italian human isolate of Salmonella serovar Napoli.

Plasmid pii:S0147-619X(21)00013-5 [Epub ahead of print].

Salmonella enterica subsp. enterica serovar Napoli (S. Napoli) ranks among the top serovars causing human infections in Italy, although not common in other European countries. Isolates are generally pan-susceptible or resistant to aminoglycosides only, however data on antimicrobial resistance genes in strains of S. Napoli are limited. Recently an isolate encoding resistance to third generation cephalosporins was reported. This study aimed to characterize plasmid-encoded cephalosporin resistance due to the blaCTX-M-15 gene in a human S. Napoli isolate in Italy, and to investigate plasmid stability over time. S. Napoli 16/174478 was confirmed to be ESBL-producing. The blaCTX-M-15 gene was shown to be located on an IncI1α plasmid of 90,272 bp (50.03 GC%) encoding for 107 coding sequences (CDS). The plasmid was successfully transferred by conjugation to an E. coli 1816 recipient strain (conjugation frequency 3.9 × 10-2 transconjugants per donor). Transconjugants were confirmed to carry the IncI1α plasmid, and to be ESBL-producing strains as well. Moreover, transconjugant colonies maintained the plasmid for up to 10 passages. The identification of S. Napoli isolates able to produce ESBLs is of great concern, as this pathogen is frequently associated with invasive infections and a higher risk of bacteraemia, and its reservoir has not yet been clearly identified.

RevDate: 2021-02-13

Cordovez V, Rotoni C, Dini-Andreote F, et al (2021)

Successive plant growth amplifies genotype-specific assembly of the tomato rhizosphere microbiome.

The Science of the total environment, 772:144825 pii:S0048-9697(20)38358-3 [Epub ahead of print].

Plant microbiome assembly is a spatial and dynamic process driven by root exudates and influenced by soil type, plant developmental stage and genotype. Genotype-dependent microbiome assembly has been reported for different crop plant species. Despite the effect of plant genetics on microbiome assembly, the magnitude of host control over its root microbiome is relatively small or, for many plant species, still largely unknown. Here we cultivated modern and wild tomato genotypes for four successive cycles and showed that divergence in microbiome assembly between the two genotypes was significantly amplified over time. Also, we show that the composition of the rhizosphere microbiome of modern and wild plants became more dissimilar from the initial bulk soil and from each other. Co-occurrence analyses further identified amplicon sequence variants (ASVs) associated with early and late successions of the tomato rhizosphere microbiome. Among the members of the Late Successional Rhizosphere microbiome, we observed an enrichment of ASVs belonging to the genera Acidovorax, Massilia and Rhizobium in the wild tomato rhizosphere, whereas the modern tomato rhizosphere was enriched for an ASV belonging to the genus Pseudomonas. Collectively, our approach allowed us to study the dynamics of rhizosphere microbiome over successional cultivation as well as to categorize rhizobacterial taxa for their ability to form transient or long-term associations with their host plants.

RevDate: 2021-02-13

Liu W, Zhang X, Xu H, et al (2021)

Microbial community heterogeneity within colorectal neoplasia and its correlation with colorectal carcinogenesis.

Gastroenterology pii:S0016-5085(21)00407-8 [Epub ahead of print].

BACKGROUND & AIMS: Gut microbial dysbiosis has pivotal involvement in colorectal cancer (CRC). However, the intratumoural microbiota and its association with CRC progression remains elusive. Hence, we aimed to determine the microbial community architecture within a neoplasia (CRC or adenoma) and its contribution to colorectal carcinogenesis.

METHODS: We collected 436 tissue biopsies from patients with CRC (n = 36) or adenoma (n = 32) (2-6 biopsies from a neoplasia plus 2-5 biopsies from adjacent normal tissues per individual). Microbial profiling was performed by 16S rRNA gene sequencing with subsequent investigation of microbiota diversities and heterogeneity. The correlation between microbial dysbiosis and host genetic alterations (KRAS mutation and microsatellite instability (MSI)) in all neoplasia biopsies was also analysed.

RESULTS: We discovered that intra-neoplasia microbial communities are heterogeneous. Abundances of some CRC-associated pathobionts (Fusobacterium, Bacteroides, Parvimonas and Prevotella) were found to be highly varied within a single neoplasia. Correlation of such heterogeneity with CRC development revealed alteration in microbial communities involving microbes with high intra-neoplasia variation in abundance. Moreover, we found that the intra-neoplasia variation in abundance of individual microbes changed along the adenoma-carcinoma sequence. We further determined significant difference in intra-neoplasia microbiota between biopsies with and without KRAS mutation (P < 0.001) or MSI (P < 0.001) and illustrated the association of intratumoural microbial heterogeneity with genetic alteration.

CONCLUSIONS: We demonstrated that intra-neoplasia microbiota is heterogeneous and correlated with colorectal carcinogenesis. Our findings provide new insights on the contribution of gut microbiota heterogeneity to CRC progression.

RevDate: 2021-02-13

Lopes LD, Hao J, DP Schachtman (2021)

Alkaline soil pH affects bulk soil, rhizosphere and root endosphere microbiomes of plants growing in a Sandhills ecosystem.

FEMS microbiology ecology pii:6134753 [Epub ahead of print].

Soil pH is a major factor shaping bulk soil microbial communities. However, it is unclear whether the belowground microbial habitats shaped by plants (e.g. rhizosphere and root endosphere) are also affected by soil pH. We investigated this question by comparing the microbial communities associated with plants growing in neutral and strongly alkaline soils in the Sandhills, which is the largest sand dune complex in the northern hemisphere. Bulk soil, rhizosphere and root endosphere DNA were extracted from multiple plant species and analyzed using 16S rRNA amplicon sequencing. Results showed that rhizosphere, root endosphere and bulk soil microbiomes were different in the contrasting soil pH ranges. The strongest impact of plant species on the belowground microbiomes was in alkaline soils, suggesting a greater selective effect under alkali stress. Evaluation of soil chemical components showed that in addition to soil pH, cation exchange capacity also had a strong impact on shaping bulk soil microbial communities. This study extends our knowledge regarding the importance of pH to microbial ecology showing that root endosphere and rhizosphere microbial communities were also influenced by this soil component, and highlights the important role that plants play particularly in shaping the belowground microbiomes in alkaline soils.

RevDate: 2021-02-13

Kellogg JA, Reganold JP, Murphy KM, et al (2021)

A Plant-Fungus Bioassay Supports the Classification of Quinoa (Chenopodium quinoa Willd.) as Inconsistently Mycorrhizal.

Microbial ecology [Epub ahead of print].

Quinoa (Chenopodium quinoa Willd.) is becoming an increasingly important food crop. Understanding the microbiome of quinoa and its relationships with soil microorganisms may improve crop yield potential or nutrient use efficiency. Whether quinoa is a host or non-host of a key soil symbiont, arbuscular mycorrhizal fungi (AMF), is suddenly up for debate with recent field studies reporting root colonization and presence of arbuscules. This research seeks to add evidence to the mycorrhizal classification of quinoa as we investigated additional conditions not previously explored in quinoa that may affect root colonization. A greenhouse study used six AMF species, two AMF commercial inoculant products, and a diverse set of 10 quinoa genotypes. Results showed 0 to 3% quinoa root colonization by AMF when grown under greenhouse conditions. Across quinoa genotypes, AMF inoculant affected shoot dry weight (p = 0.066) and height (p = 0.031). Mykos Gold produced greater dry biomass than Claroideoglomus eutunicatum (27% increase), Rhizophagus clarus (26% increase), and within genotype CQ119, the control (21% increase). No treatment increased plant height compared to control, but Funneliformis mosseae increased height compared to C. eutunicatum (25% increase) and Rhizophagus intraradices (25% increase). Although quinoa plants were minimally colonized by AMF, plant growth responses fell along the mutualism-parasitism continuum. Individual AMF treatments increased leaf greenness in quinoa genotypes 49ALC and QQ87, while R. clarus decreased greenness in CQ119 compared to the control. Our research findings support the recommendation to classify quinoa as non-mycorrhizal when no companion plant is present and inconsistently mycorrhizal when conditional colonization occurs.

RevDate: 2021-02-13

He Y, Huang D, Li S, et al (2021)

Profiling of Microbial Communities in the Sediments of Jinsha River Watershed Exposed to Different Levels of Impacts by the Vanadium Industry, Panzhihua, China.

Microbial ecology [Epub ahead of print].

The mining, smelting, manufacturing, and disposal of vanadium (V) and associated products have caused serious environmental problems. Although the microbial ecology in V-contaminated soils has been intensively studied, the impacted watershed ecosystems have not been systematically investigated. In this study, geochemistry and microbial structure were analyzed along ~30 km of the Jinsha River and its two tributaries across the industrial areas in Panzhihua, one of the primary V mining and production cities in China. Geochemical analyses showed different levels of contamination by metals and metalloids in the sediments, with high degrees of contamination observed in one of the tributaries close to the industrial park. Analyses of the V4 hypervariable region of 16S rRNA genes of the microbial communities in the sediments showed significant decrease in microbial diversity and microbial structure in response to the environmental gradient (e.g., heavy metals, total sulfur, and total nitrogen). Strong association of the taxa (e.g., Thauera, Algoriphagus, Denitromonas, and Fontibacter species) with the metals suggested selection for these potential metal-resistant and/or metabolizing populations. Further co-occurrence network analysis showed that many identified potential metal-mediating species were among the keystone taxa that were closely associated in the same module, suggesting their strong inter-species interactions but relative independence from other microorganisms in the hydrodynamic ecosystems. This study provided new insight into the microbe-environment interactions in watershed ecosystems differently impacted by the V industries. Some of the phylotypes identified in the highly contaminated samples exhibited potential for bioremediation of toxic metals (e.g., V and Cr).

RevDate: 2021-02-13

Coban O, Rasigraf O, de Jong AEE, et al (2021)

Quantifying potential N turnover rates in hypersaline microbial mats by 15N tracer techniques.

Applied and environmental microbiology pii:AEM.03118-20 [Epub ahead of print].

Microbial mats, due to stratification of the redox zones, have a potential to include a complete N cycle, however an attempt to evaluate a complete N cycle in these ecosystems has not been yet made. In this study, occurrence and rates of major N cycle processes were evaluated in intact microbial mats from Elkhorn Slough, Monterey Bay, CA, USA, and Baja California Sur, Mexico under oxic and anoxic conditions using 15N-labeling techniques. All of the major N transformation pathways, with the exception of anammox, were detected in both microbial mats. Nitrification rates were found to be low at both sites for both seasons investigated. The highest rates of ammonium assimilation were measured in Elkhorn Slough mats in April and corresponded to high in situ ammonium concentration in the overlying water. Baja mats featured higher ammonification than ammonium assimilation rates and this, along with their higher affinity for nitrate compared to ammonium and low dissimilatory nitrate reduction to ammonium rates, characterized their differences from Elkhorn Slough mats. Nitrogen fixation rates in Elkhorn Slough microbial mats were found to be low implying that other processes such as recycling and assimilation from water are main sources of N for these mats at the times sampled. Denitrification in all of the mats was incomplete with nitrous oxide as end product and not dinitrogen. Our findings highlight N cycling features not previously quantified in microbial mats and indicate a need of further investigations in these microbial ecosystems.Importance: Nitrogen is essential for life. The nitrogen cycle on Earth is mediated by microbial activity and has had a profound impact on both the atmosphere and the biosphere throughout geologic time. Microbial mats, present in many modern environments, have been regarded as living records of the organisms, genes, and phylogenies of microbes, as they are one of the most ancient ecosystems on Earth. While rates of major nitrogen metabolic pathways have been evaluated in a number of ecosystems, it remains elusive in microbial mats. In particular it is unclear what factors affect nitrogen cycling in these ecosystems and how morphological differences between mats impact nitrogen transformations. In this study we investigate nitrogen cycling in two microbial mats having morphological differences. Our findings provide insight for further understanding of biogeochemistry and microbial ecology of microbial mats.

RevDate: 2021-02-15

Jiang C, Peces M, Andersen MH, et al (2021)

Characterizing the growing microorganisms at species level in 46 anaerobic digesters at Danish wastewater treatment plants: A six-year survey on microbial community structure and key drivers.

Water research, 193:116871 pii:S0043-1354(21)00069-5 [Epub ahead of print].

Anaerobic digestion (AD) is a key technology at many wastewater treatment plants (WWTPs) for converting primary and surplus activated sludge to methane-rich biogas. However, the limited number of surveys and the lack of comprehensive datasets have hindered a deeper understanding of the characteristics and associations between key variables and the microbial community composition. Here, we present a six-year survey of 46 anaerobic digesters, located at 22 WWTPs in Denmark, which is the first and largest known study of the microbial ecology of AD at WWTPs at a regional scale. For three types of AD (mesophilic, mesophilic with thermal hydrolysis pretreatment, and thermophilic), we present the typical value range of 12 key parameters including operational variables and performance parameters. High-resolution bacterial and archaeal community analyses were carried out at species level using amplicon sequencing of >1,000 samples and the new ecosystem-specific MiDAS 3 reference database. We detected 42 phyla, 1,600 genera, and 3,584 species in the bacterial community, where 70% of the genera and 93% of the species represented environmental taxa that were only classified based on MiDAS 3 de novo placeholder taxonomy. More than 40% of the bacterial species were found not to grow in the mesophilic and thermophilic digesters and were only present due to immigration with the feed sludge. Ammonium concentration was the main driver shaping the bacterial community while temperature and pH were main drivers for the archaea in the three types of ADs. Sub-setting for the growing microbes improved significantly the correlation analyses and revealed the main drivers for the presence of specific species. Within mesophilic digesters, feed sludge composition and other key parameters (organic loading rate, biogas yield, and ammonium concentration) correlated with specific growing species. This survey provides a comprehensive insight into community structure at species level, providing a foundation for future studies of the ecological significance/characteristics and function of the many novel or poorly described taxa.

RevDate: 2021-02-15

Pratscher J (2021)

Extraction of Microbial Cells from Environmental Samples for FISH Approaches.

Methods in molecular biology (Clifton, N.J.), 2246:291-299.

Fluorescent in situ hybridization (FISH) on environmental samples has become a standard technique to identify and enumerate microbial populations. However, visualization and quantification of cells in environmental samples with complex matrices is often challenging to impossible, and downstream protocols might also require the absence of organic and inorganic particles for analysis. Therefore, quite often microbial cells have to be detached and extracted from the sample matrix prior to use in FISH. Here, details are given for a routine protocol to extract intact microbial cells from environmental samples using density gradient centrifugation. This protocol is suitable and adaptable for a wide range of environmental samples.

RevDate: 2021-02-15

Nielsen JL (2021)

Assigning Function to Phylogeny: MAR-FISH.

Methods in molecular biology (Clifton, N.J.), 2246:225-236.

Microautoradiography (MAR) is a technique by which assimilated radioactive tracers incorporated into the biomass can be detected by a film emulsion. This allows for the testing of cellular preferences in electron donors and acceptors of individual cells in complex microbial assemblages, as well as the ability to take up substrates under diverse environmental exposures.Combination with staining techniques such as fluorescence in situ hybridization (FISH) can be used to identify the involved cells. Here, the practical aspects of a combined microautoradiography and fluorescence in situ hybridization (MAR-FISH) approach are described.

RevDate: 2021-02-12

Zhou G, Tong H, Cai L, et al (2021)

Transgenerational Effects on the Coral Pocillopora damicornis Microbiome Under Ocean Acidification.

Microbial ecology [Epub ahead of print].

Reef-building corals are inhabited by functionally diverse microorganisms which play important roles in coral health and persistence in the Anthropocene. However, our understanding of the complex associations within coral holobionts is largely limited, particularly transgenerational exposure to environmental stress, like ocean acidification. Here we investigated the microbiome development of an ecologically important coral Pocillopora damicornis following transgenerational exposure to moderate and high pCO2 (partial pressure of CO2) levels, using amplicon sequencing and analysis. Our results showed that the Symbiodiniaceae community structures in adult and juvenile had similar patterns, all of which were dominated by Durusdinium spp., previously known as clade D. Conversely, prokaryotic communities varied between adults and juveniles, possibly driven by the effect of host development. Surprisingly, there were no significant changes in both Symbiodiniaceae and prokaryotic communities with different pCO2 treatments, which was independent of the life history stage. This study shows that ocean acidification has no significant effect on P. damicornis microbiome, and warrants further research to test whether transgenerational acclimation exists in coral holobiont to projected future climate change.

RevDate: 2021-02-13

Yang P, Tan C, Han M, et al (2020)

Correlation-Centric Network (CCN) representation for microbial co-occurrence patterns: new insights for microbial ecology.

NAR genomics and bioinformatics, 2(2):lqaa042.

Mainstream studies of microbial community focused on critical organisms and their physiology. Recent advances in large-scale metagenome analysis projects initiated new researches in the complex correlations between large microbial communities. Specifically, previous studies focused on the nodes (i.e. species) of the Species-Centric Networks (SCNs). However, little was understood about the change of correlation between network members (i.e. edges of the SCNs) when the network was disturbed. Here, we introduced a Correlation-Centric Network (CCN) to the microbial research based on the concept of edge networks. In CCN, each node represented a species-species correlation, and edge represented the species shared by two correlations. In this research, we investigated the CCNs and their corresponding SCNs on two large cohorts of microbiome. The results showed that CCNs not only retained the characteristics of SCNs, but also contained information that cannot be detected by SCNs. In addition, when the members of microbial communities were decreased (i.e. environmental disturbance), the CCNs fluctuated within a small range in terms of network connectivity. Therefore, by highlighting the important species correlations, CCNs could unveil new insights when studying not only the functions of target species, but also the stabilities of their residing microbial communities.

RevDate: 2021-02-11

Franco-Frías E, Mercado-Guajardo V, Merino-Mascorro A, et al (2021)

Analysis of Bacterial Communities by 16S rRNA Gene Sequencing in a Melon-Producing Agro-environment.

Microbial ecology [Epub ahead of print].

Cantaloupe melons, which have been responsible of an increasing number of foodborne disease outbreaks, may become contaminated with microbial pathogens during production. However, little information is available on the microbial populations in the cantaloupe farm environment. The purpose of this work was to characterize the bacterial communities present on cantaloupe farms. Fruit, soil, and harvester hand rinsates were collected from two Mexican cantaloupe farms, each visited three times. Microbiome analysis was performed by sequencing 16sRNA and analyzed using qiime2 software. Correlations were determined between sample type and microbial populations. The α and β diversity analysis identified 2777 sequences across all samples. The soil samples had the highest number and diversity of unique species (from 130 to 1329 OTUs); cantaloupe (from 112 to 205 OTUs), and hands (from 67 to 151 OTUs) had similar diversity. Collectively, Proteobacteria was the most abundant phyla (from 42 to 95%), followed by Firmicutes (1-47%), Actinobacteria (< 1 to 23%), and Bacteroidetes (< 1 to 4.8%). The most abundant genera were Acinetobacter (20-58%), Pseudomonas (14.5%), Erwinia (13%), and Exiguobacterium (6.3%). Genera with potential to be pathogenic included Bacillus (4%), Salmonella (0.85%), Escherichia-Shigella (0.38%), Staphylococcus (0.32%), Listeria (0.29%), Clostridium (0.28%), and Cronobacter (0.27%), which were found at lower frequencies. This study provides information on the cantaloupe production microbiome, which can inform future research into critical food safety issues such as antimicrobial resistance, virulence, and genomic epidemiology.

RevDate: 2021-02-12

Aubry F, Jacobs S, Darmuzey M, et al (2021)

Recent African strains of Zika virus display higher transmissibility and fetal pathogenicity than Asian strains.

Nature communications, 12(1):916.

The global emergence of Zika virus (ZIKV) revealed the unprecedented ability for a mosquito-borne virus to cause congenital birth defects. A puzzling aspect of ZIKV emergence is that all human outbreaks and birth defects to date have been exclusively associated with the Asian ZIKV lineage, despite a growing body of laboratory evidence pointing towards higher transmissibility and pathogenicity of the African ZIKV lineage. Whether this apparent paradox reflects the use of relatively old African ZIKV strains in most laboratory studies is unclear. Here, we experimentally compare seven low-passage ZIKV strains representing the recently circulating viral genetic diversity. We find that recent African ZIKV strains display higher transmissibility in mosquitoes and higher lethality in both adult and fetal mice than their Asian counterparts. We emphasize the high epidemic potential of African ZIKV strains and suggest that they could more easily go unnoticed by public health surveillance systems than Asian strains due to their propensity to cause fetal loss rather than birth defects.

RevDate: 2021-02-12

Westhoff S, Kloosterman AM, van Hoesel SFA, et al (2021)

Competition Sensing Changes Antibiotic Production in Streptomyces.

mBio, 12(1):.

One of the most important ways that bacteria compete for resources and space is by producing antibiotics that inhibit competitors. Because antibiotic production is costly, the biosynthetic gene clusters coordinating their synthesis are under strict regulatory control and often require "elicitors" to induce expression, including cues from competing strains. Although these cues are common, they are not produced by all competitors, and so the phenotypes causing induction remain unknown. By studying interactions between 24 antibiotic-producing strains of streptomycetes, we show that strains commonly inhibit each other's growth and that this occurs more frequently if strains are closely related. Next, we show that antibiotic production is more likely to be induced by cues from strains that are closely related or that share secondary metabolite biosynthetic gene clusters (BGCs). Unexpectedly, antibiotic production is less likely to be induced by competitors that inhibit the growth of a focal strain, indicating that cell damage is not a general cue for induction. In addition to induction, antibiotic production often decreases in the presence of a competitor, although this response was not associated with genetic relatedness or overlap in BGCs. Finally, we show that resource limitation increases the chance that antibiotic production declines during competition. Our results reveal the importance of social cues and resource availability in the dynamics of interference competition in streptomycetes.IMPORTANCE Bacteria secrete antibiotics to inhibit their competitors, but the presence of competitors can determine whether these toxins are produced. Here, we study the role of the competitive and resource environment on antibiotic production in Streptomyces, bacteria renowned for their production of antibiotics. We show that Streptomyces cells are more likely to produce antibiotics when grown with competitors that are closely related or that share biosynthetic pathways for secondary metabolites, but not when they are threatened by competitor's toxins, in contrast to predictions of the competition sensing hypothesis. Streptomyces cells also often reduce their output of antibiotics when grown with competitors, especially under nutrient limitation. Our findings highlight that interactions between the social and resource environments strongly regulate antibiotic production in these medicinally important bacteria.

RevDate: 2021-02-10

Otwell AE, Carr AV, Majumder ELW, et al (2021)

Sulfur Metabolites Play Key System-Level Roles in Modulating Denitrification.

mSystems, 6(1):.

Competition between nitrate-reducing bacteria (NRB) and sulfate-reducing bacteria (SRB) for resources in anoxic environments is generally thought to be governed largely by thermodynamics. It is now recognized that intermediates of nitrogen and sulfur cycling (e.g., hydrogen sulfide, nitrite, etc.) can also directly impact NRB and SRB activities in freshwater, wastewater, and sediment and therefore may play important roles in competitive interactions. Here, through comparative transcriptomic and metabolomic analyses, we have uncovered mechanisms of hydrogen sulfide- and cysteine-mediated inhibition of nitrate respiratory growth for the NRB Intrasporangium calvum C5. Specifically, the systems analysis predicted that cysteine and hydrogen sulfide inhibit growth of I. calvum C5 by disrupting distinct steps across multiple pathways, including branched-chain amino acid (BCAA) biosynthesis, utilization of specific carbon sources, and cofactor metabolism. We have validated these predictions by demonstrating that complementation with BCAAs and specific carbon sources relieves the growth inhibitory effects of cysteine and hydrogen sulfide. We discuss how these mechanistic insights give new context to the interplay and stratification of NRB and SRB in diverse environments.IMPORTANCE Nitrate-reducing bacteria (NRB) and sulfate-reducing bacteria (SRB) colonize diverse anoxic environments, including soil subsurface, groundwater, and wastewater. NRB and SRB compete for resources, and their interplay has major implications on the global cycling of nitrogen and sulfur species, with undesirable outcomes in some contexts. For instance, the removal of reactive nitrogen species by NRB is desirable for wastewater treatment, but in agricultural soils, NRB can drive the conversion of nitrates from fertilizers into nitrous oxide, a potent greenhouse gas. Similarly, the hydrogen sulfide produced by SRB can help sequester and immobilize toxic heavy metals but is undesirable in oil wells where competition between SRB and NRB has been exploited to suppress hydrogen sulfide production. By characterizing how reduced sulfur compounds inhibit growth and activity of NRB, we have gained systems-level and mechanistic insight into the interplay of these two important groups of organisms and drivers of their stratification in diverse environments.

RevDate: 2021-02-10

de la Cuesta-Zuluaga J, Spector TD, Youngblut ND, et al (2021)

Genomic Insights into Adaptations of Trimethylamine-Utilizing Methanogens to Diverse Habitats, Including the Human Gut.

mSystems, 6(1):.

Archaea of the order Methanomassiliicoccales use methylated amines such as trimethylamine as the substrates for methanogenesis. They form two large phylogenetic clades and reside in diverse environments, from soil to the human gut. Two genera, one from each clade, inhabit the human gut: Methanomassiliicoccus, which has one cultured representative, and "Candidatus Methanomethylophilus," which has none. Questions remain regarding their distribution across biomes and human populations, their association with other taxa in the gut, and whether host genetics correlate with their abundance. To gain insight into the Methanomassiliicoccales clade, particularly its human-associated members, we performed a genomic comparison of 72 Methanomassiliicoccales genomes and assessed their presence in metagenomes derived from the human gut (n = 4,472, representing 22 populations), nonhuman animal gut (n = 145), and nonhost environments (n = 160). Our analyses showed that all taxa are generalists; they were detected in animal gut and environmental samples. We confirmed two large clades, one enriched in the gut and the other enriched in the environment, with notable exceptions. Genomic adaptations to the gut include genome reduction and genes involved in the shikimate pathway and bile resistance. Genomic adaptations differed by clade, not habitat preference, indicating convergent evolution between the clades. In the human gut, the relative abundance of Methanomassiliicoccales spp. correlated with trimethylamine-producing bacteria and was unrelated to host genotype. Our results shed light on the microbial ecology of this group and may help guide Methanomassiliicoccales-based strategies for trimethylamine mitigation in cardiovascular disease.IMPORTANCEMethanomassiliicoccales are less-known members of the human gut archaeome. Members of this order use methylated amines, including trimethylamine, in methane production. This group has only one cultured representative; how its members adapted to inhabit the mammalian gut and how they interact with other microbes is largely unknown. Using bioinformatics methods applied to DNA from a wide range of samples, we profiled the abundances of these Archaea spp. in environmental and host-associated microbial communities. We observed two groups of Methanomassiliicoccales, one largely host associated and one largely found in environmental samples, with some exceptions. When host associated, these Archaea have smaller genomes and possess genes related to bile resistance and aromatic amino acid precursors. We did not detect Methanomassiliicoccales in all human populations tested, but when present, they were correlated with bacteria known to produce trimethylamine. Due to their metabolism of trimethylamine, these intriguing Archaea may form the basis of novel therapies for cardiovascular disease.

RevDate: 2021-02-10

Maillet A, Denojean P, Bouju-Albert A, et al (2021)

Characterization of Bacterial Communities of Cold-Smoked Salmon during Storage.

Foods (Basel, Switzerland), 10(2): pii:foods10020362.

Cold-smoked salmon is a widely consumed ready-to-eat seafood product that is a fragile commodity with a long shelf-life. The microbial ecology of cold-smoked salmon during its shelf-life is well known. However, to our knowledge, no study on the microbial ecology of cold-smoked salmon using next-generation sequencing has yet been undertaken. In this study, cold-smoked salmon microbiotas were investigated using a polyphasic approach composed of cultivable methods, V3-V4 16S rRNA gene metabarcoding and chemical analyses. Forty-five cold-smoked salmon products processed in three different factories were analyzed. The metabarcoding approach highlighted 12 dominant genera previously reported as fish spoilers: Firmicutes Staphylococcus, Carnobacterium, Lactobacillus, β-Proteobacteria Photobacterium, Vibrio, Aliivibrio, Salinivibrio, Enterobacteriaceae Serratia,Pantoea, γ-Proteobacteria Psychrobacter, Shewanella and Pseudomonas. Specific operational taxonomic units were identified during the 28-day storage study period. Operational taxonomic units specific to the processing environment were also identified. Although the 45 cold-smoked salmon products shared a core microbiota, a processing plant signature was found. This suggest that the bacterial communities of cold-smoked salmon products are impacted by the processing environment, and this environment could have a negative effect on product quality. The use of a polyphasic approach for seafood products and food processing environments could provide better insights into residential bacteria dynamics and their impact on food safety and quality.

RevDate: 2021-02-10

Szczypta A, Talaga-Ćwiertnia K, Kielar M, et al (2021)

Investigation of Acinetobacter baumannii Activity in Vascular Surgery Units through Epidemiological Management Based on the Analysis of Antimicrobial Resistance, Biofilm Formation and Genotyping.

International journal of environmental research and public health, 18(4): pii:ijerph18041563.

BACKGROUND/OBJECTIVES: The genus Acinetobacter demonstrates resistance to antibiotics and has been shown to spread in the hospital environment causing epidemic outbreaks among hospitalized patients. The objectives of the present study was to investigate the antibiotic resistance, biofilm formation, and clonality among Acinetobacter baumannii strains.

MATERIALS AND METHODS: The study involved 6 (I Outbreak) and 3 (II Outbreak) A. baumannii strains isolated from patients hospitalized in vascular surgery unit.

RESULTS: All tested A. baumannii strains were extensively drug resistant (XDR) and all the isolates were carbapenem-resistant and among them, all carried the blaOXA-51 gene, the blaOXA-24 gene, as well as the blaOXA-23 gene. All of the investigated strains had the ability to form a biofilm, but all of them produced less biofilm than the reference strain. Multi-locus sequence typing (MLST) showed that all strains belonged to the ST2 clone. Pulsed-field gel electrophoresis (PFGE) divided the tested outbreak strains into two clones (A and B).

CONCLUSION: This study shows a nosocomial spread of XDR A. baumannii ST2 having the blaOXA-51 gene, the blaOXA-24 gene, as well as the blaOXA-23 gene, low biofilm formers, that was prevalent in the vascular surgery unit. To identify the current situation of vascular surgery departments targeted epidemiological investigation was needed. Effective implementation of infection control prevented the spread of the epidemic outbreaks.

RevDate: 2021-02-11

Higgins P, Grace CA, Lee SA, et al (2021)

Whole-genome sequencing from the New Zealand Saccharomyces cerevisiae population reveals the genomic impacts of novel microbial range expansion.

G3 (Bethesda, Md.), 11(1):.

Saccharomyces cerevisiae is extensively utilized for commercial fermentation, and is also an important biological model; however, its ecology has only recently begun to be understood. Through the use of whole-genome sequencing, the species has been characterized into a number of distinct subpopulations, defined by geographical ranges and industrial uses. Here, the whole-genome sequences of 104 New Zealand (NZ) S. cerevisiae strains, including 52 novel genomes, are analyzed alongside 450 published sequences derived from various global locations. The impact of S. cerevisiae novel range expansion into NZ was investigated and these analyses reveal the positioning of NZ strains as a subgroup to the predominantly European/wine clade. A number of genomic differences with the European group correlate with range expansion into NZ, including 18 highly enriched single-nucleotide polymorphism (SNPs) and novel Ty1/2 insertions. While it is not possible to categorically determine if any genetic differences are due to stochastic process or the operations of natural selection, we suggest that the observation of NZ-specific copy number increases of four sugar transporter genes in the HXT family may reasonably represent an adaptation in the NZ S. cerevisiae subpopulation, and this correlates with the observations of copy number changes during adaptation in small-scale experimental evolution studies.

RevDate: 2021-02-09

Ayyasamy A, Kempraj V, KJ Pagadala Damodaram (2021)

Endosymbiotic Bacteria Aid to Overcome Temperature Induced Stress in the Oriental Fruit Fly, Bactrocera dorsalis.

Microbial ecology [Epub ahead of print].

Endosymbiotic microbiota are known to have an enormous impact on their host, influencing its physiology, behavior, fitness, and various other aspects. The present study hypothesizes that certain bacterial symbionts aid the Oriental fruit fly, Bactrocera dorsalis in its adaptation to survive thermal stress encountered in the environment. Investigative studies on the change in gut and reproductive tract microbiota diversity of male and female B. dorsalis revealed that certain genera of Acinetobacter, Brevibacillus, Bacillus, Enterobacter, Enterococcus, Pseudomonas, and Staphylococcus were involved in the adaptation of B. dorsalis to temperature stresses. The intestinal and reproductive tract bacterial community of B. dorsalis varied depending on the temperature the insects were reared at. We hypothesized that the microbiota present in B. dorsalis' gut helped it endure temperature stresses over prolonged periods. Out of 54 bacterial isolates, 25, 15, and 14 isolates were obtained from flies reared at 27 °C, 18 °C, and 35 °C, respectively. A 16S rDNA analysis revealed that the bacterial isolates (reared at different temperatures) belonged to different genera. The flies were supplemented with antibiotics to suppress the existing gut microbiota and subsequently fed with bacterial isolates from flies reared at 18 °C, 27 °C (control) or 35 °C separately. When these flies were placed in incubators pre-set at the above temperatures, the survival rate exhibited by the flies differed significantly. The flies fed with bacterial isolates from 18 °C could survive only in incubators pre-set at 18 °C, while flies fed with bacterial isolates from 35 °C could survive only at 35 °C and not vice versa. The microbiota supplementation assay established that the presence of specific bacterial isolates aided the flies' survival under varied thermal stresses.

RevDate: 2021-02-09

Joshi S, Robles A, Aguiar S, et al (2021)

The occurrence and ecology of microbial chain elongation of carboxylates in soils.

The ISME journal [Epub ahead of print].

Chain elongation is a growth-dependent anaerobic metabolism that combines acetate and ethanol into butyrate, hexanoate, and octanoate. While the model microorganism for chain elongation, Clostridium kluyveri, was isolated from a saturated soil sample in the 1940s, chain elongation has remained unexplored in soil environments. During soil fermentative events, simple carboxylates and alcohols can transiently accumulate up to low mM concentrations, suggesting in situ possibility of microbial chain elongation. Here, we examined the occurrence and microbial ecology of chain elongation in four soil types in microcosms and enrichments amended with chain elongation substrates. All soils showed evidence of chain elongation activity with several days of incubation at high (100 mM) and environmentally relevant (2.5 mM) concentrations of acetate and ethanol. Three soils showed substantial activity in soil microcosms with high substrate concentrations, converting 58% or more of the added carbon as acetate and ethanol to butyrate, butanol, and hexanoate. Semi-batch enrichment yielded hexanoate and octanoate as the most elongated products and microbial communities predominated by C. kluyveri and other Firmicutes genera not known to undergo chain elongation. Collectively, these results strongly suggest a niche for chain elongation in anaerobic soils that should not be overlooked in soil microbial ecology studies.

RevDate: 2021-02-08

Dou W, Miao Y, Xiao J, et al (2021)

Association of Wolbachia with Gene Expression in Drosophila Testes.

Microbial ecology [Epub ahead of print].

Wolbachia is a genus of intracellular symbiotic bacteria that are widely distributed in arthropods and nematodes. These maternally inherited bacteria regulate host reproductive systems in various ways to facilitate their vertical transmission. Since the identification of Wolbachia in many insects, the relationship between Wolbachia and the host has attracted great interest. Numerous studies have indicated that Wolbachia modifies a variety of biological processes in the host. Previous studies in Drosophila melanogaster (D. melanogaster) have demonstrated that Wolbachia can affect spermatid differentiation, chromosome deposition, and sperm activity in the early stages of spermatogenesis, leading to sperm dysfunction. Here, we explored the putative effect of Wolbachia in sperm maturation using transcriptomic approaches to compare gene expression in Wolbachia-infected and Wolbachia-free D. melanogaster adult testes. Our findings show that Wolbachia affects many biological processes in D. melanogaster adult testes, and most of the differentially expressed genes involved in carbohydrate metabolism, lysosomal degradation, proteolysis, lipid metabolism, and immune response were upregulated in the presence of Wolbachia. In contrast, some genes that are putatively associated with cutin and wax biosynthesis and peroxisome pathways were downregulated. We did not find any differentially expressed genes that are predicted to be related to spermatogenesis in the datasets. This work provides additional information for understanding the Wolbachia-host intracellular relationships.

RevDate: 2021-02-08

Grzesiak J, Woltyńska A, Zdanowski MK, et al (2021)

Metabolic fingerprinting of the Antarctic cyanolichen Leptogium puberulum-associated bacterial community (Western Shore of Admiralty Bay, King George Island, Maritime Antarctica).

Microbial ecology [Epub ahead of print].

Lichens are presently regarded as stable biotopes, small ecosystems providing a safe haven for the development of a diverse and numerous microbiome. In this study, we conducted a functional diversity assessment of the microbial community residing on the surface and within the thalli of Leptogium puberulum, a eurytopic cyanolichen endemic to Antarctica, employing the widely used Biolog EcoPlates which test the catabolism of 31 carbon compounds in a colorimetric respiration assay. Lichen thalli occupying moraine ridges of differing age within a proglacial chronosequence, as well as those growing in sites of contrasting nutrient concentrations, were procured from the diverse landscape of the western shore of Admiralty Bay in Maritime Antarctica. The L. puberulum bacterial community catabolized photobiont- (glucose-containing carbohydrates) and mycobiont-specific carbon compounds (D-Mannitol). The bacteria also had the ability to process degradation products of lichen thalli components (D-cellobiose and N-acetyl-D-glucosamine). Lichen thalli growth site characteristics had an impact on metabolic diversity and respiration intensity of the bacterial communities. While high nutrient contents in lichen specimens from "young" proglacial locations and in those from nitrogen enriched sites stimulated bacterial catabolic activity, in old proglacial locations and in nutrient-lacking sites, a metabolic activity restriction was apparent, presumably due to lichen-specific microbial control mechanisms.

RevDate: 2021-02-10

Yang Q, Zou P, Cao Z, et al (2020)

QseC Inhibition as a Novel Antivirulence Strategy for the Prevention of Acute Hepatopancreatic Necrosis Disease (AHPND)-Causing Vibrio parahaemolyticus.

Frontiers in cellular and infection microbiology, 10:594652.

Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus resulted in great economic losses in global shrimp aquaculture. There is an urgent need for development of novel strategies to combat AHPND-causing V. parahaemolyticus (VpAHPND), given that one of the greatest challenges currently is the widespread use of antibiotics and subsequent emergence of multidrug-resistant bacteria. Here, we proposed a broad-spectrum antivirulence approach targeting a conserved histidine kinase, QseC, which has been demonstrated to activate virulence expression in several Gram-negative pathogens. Our results showed that QseC mediated the catecholamine stimulated effects on growth and flagellar motility of VpAHPND. Transcriptome analysis revealed that QseC was involved in the global regulation of the virulence of VpAHPND as the ΔqseC mutant exhibited a decreased expression of genes related to type IV pilin, flagellar motility, and biofilm formation, while an overexpression of type VI secretion system and cell wall biosynthesis. Subsequently, the bacterial catecholamine receptor antagonist LED209 not only neutralized the stimulatory effects of host catecholamines on the growth and motility of VpAHPNDin vitro, but also attenuated the virulence of VpAHPND towards brine shrimp larvae and white shrimp in vivo. Additionally, LED209 presented no interference with pathogen growth, nor the toxicity to the experimental animals. These results suggest that QseC can be an attractive antivirulence therapy target, and LED209 is a promising candidate for development of broad-spectrum antivirulence agents. This is the first study that demonstrated the role of QseC in the global regulation of VpAHPND infection and demonstrated the antivirulence potential of LED209, which provides insight into the use of an antivirulence approach for targeting not only VpAHPND, but also a much larger collection of pathogenic bacteria.

RevDate: 2021-02-10

Bovio-Winkler P, Cabezas A, C Etchebehere (2020)

Database Mining to Unravel the Ecology of the Phylum Chloroflexi in Methanogenic Full Scale Bioreactors.

Frontiers in microbiology, 11:603234.

Although microbial communities of anaerobic bioreactors have been extensively studied using DNA-based tools, there are still several knowledge gaps regarding the microbiology of the process, in particular integration of all generated data is still limited. One understudied core phylum within anaerobic bioreactors is the phylum Chloroflexi, despite being one of the most abundant groups in anaerobic reactors. In order to address the abundance, diversity and phylogeny of this group in full-scale methanogenic reactors globally distributed, a compilation of 16S ribosomal RNA gene sequence data from 62 full-scale methanogenic reactors studied worldwide, fed either with wastewater treatment anaerobic reactors (WTARs) or solid-waste treatment anaerobic reactors (STARs), was performed. One of the barriers to overcome was comparing data generated using different primer sets and different sequencing platforms. The sequence analysis revealed that the average abundance of Chloroflexi in WTARs was higher than in STARs. Four genera belonging to the Anaerolineae class dominated both WTARs and STARs but the core populations were different. According to the phylogenetic analysis, most of the sequences formed clusters with no cultured representatives. The Anaerolineae class was more abundant in reactors with granular biomass than in reactors with disperse biomass supporting the hypothesis that Anaerolineae play an important role in granule formation and structure due to their filamentous morphology. Cross-study comparisons can be fruitfully used to understand the complexity of the anaerobic digestion process. However, more efforts are needed to standardize protocols and report metadata information.

RevDate: 2021-02-10

García-Ulloa MI, Escalante AE, Moreno-Letelier A, et al (2020)

Evolutionary Rescue of an Environmental Pseudomonas otitidis in Response to Anthropogenic Perturbation.

Frontiers in microbiology, 11:563885.

Anthropogenic perturbations introduce novel selective pressures to natural environments, impacting the genomic variability of organisms and thus altering the evolutionary trajectory of populations. Water overexploitation for agricultural purposes and defective policies in Cuatro Cienegas, Coahuila, Mexico, have strongly impacted its water reservoir, pushing entire hydrological systems to the brink of extinction along with their native populations. Here, we studied the effects of continuous water overexploitation on an environmental aquatic lineage of Pseudomonas otitidis over a 13-year period which encompasses three desiccation events. By comparing the genomes of a population sample from 2003 (original state) and 2015 (perturbed state), we analyzed the demographic history and evolutionary response to perturbation of this lineage. Through coalescent simulations, we obtained a demographic model of contraction-expansion-contraction which points to the occurrence of an evolutionary rescue event. Loss of genomic and nucleotide variation alongside an increment in mean and variance of Tajima's D, characteristic of sudden population expansions, support this observation. In addition, a significant increase in recombination rate (R/θ) was observed, pointing to horizontal gene transfer playing a role in population recovery. Furthermore, the gain of phosphorylation, DNA recombination, small-molecule metabolism and transport and loss of biosynthetic and regulatory genes suggest a functional shift in response to the environmental perturbation. Despite subsequent sampling events in the studied site, no pseudomonad was found until the lagoon completely dried in 2017. We speculate about the causes of P. otitidis final decline or possible extinction. Overall our results are evidence of adaptive responses at the genomic level of bacterial populations in a heavily exploited aquifer.

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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.

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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.

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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.

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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.

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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).

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

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Selected Bibliographies

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