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Bibliography on: Biodiversity and Metagenomics

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ESP: PubMed Auto Bibliography 15 Sep 2019 at 01:30 Created: 

Biodiversity and Metagenomics

If evolution is the only light in which biology makes sense, and if variation is the raw material upon which selection works, then variety is not merely the spice of life, it is the essence of life — the sine qua non without which life could not exist. To understand biology, one must understand its diversity. Historically, studies of biodiversity were directed primarily at the realm of multicellular eukaryotes, since few tools existed to allow the study of non-eukaryotes. Because metagenomics allows the study of intact microbial communities, without requiring individual cultures, it provides a tool for understanding this huge, hitherto invisible pool of biodiversity, whether it occurs in free-living communities or in commensal microbiomes associated with larger organisms.

Created with PubMed® Query: biodiversity metagenomics NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-09-13
CmpDate: 2019-09-13

Wu L, Ning D, Zhang B, et al (2019)

Global diversity and biogeography of bacterial communities in wastewater treatment plants.

Nature microbiology, 4(7):1183-1195.

Microorganisms in wastewater treatment plants (WWTPs) are essential for water purification to protect public and environmental health. However, the diversity of microorganisms and the factors that control it are poorly understood. Using a systematic global-sampling effort, we analysed the 16S ribosomal RNA gene sequences from ~1,200 activated sludge samples taken from 269 WWTPs in 23 countries on 6 continents. Our analyses revealed that the global activated sludge bacterial communities contain ~1 billion bacterial phylotypes with a Poisson lognormal diversity distribution. Despite this high diversity, activated sludge has a small, global core bacterial community (n = 28 operational taxonomic units) that is strongly linked to activated sludge performance. Meta-analyses with global datasets associate the activated sludge microbiomes most closely to freshwater populations. In contrast to macroorganism diversity, activated sludge bacterial communities show no latitudinal gradient. Furthermore, their spatial turnover is scale-dependent and appears to be largely driven by stochastic processes (dispersal and drift), although deterministic factors (temperature and organic input) are also important. Our findings enhance our mechanistic understanding of the global diversity and biogeography of activated sludge bacterial communities within a theoretical ecology framework and have important implications for microbial ecology and wastewater treatment processes.

RevDate: 2019-09-13
CmpDate: 2019-09-13

Wang Y, F Staubach (2018)

Individual variation of natural D.melanogaster-associated bacterial communities.

FEMS microbiology letters, 365(6):.

Drosophila melanogaster has become an important model organism to study host-microbe interaction in the laboratory. However, the natural microbial communities that are associated with D. melanogaster have received less attention. Especially, information on inter-individual variation is still lacking, because most studies so far have used pooled material from several flies. Here, we collected bacterial 16S rRNA gene community profiles from a set of 32 individuals from a single population. We simulated pools from the individual data (i) to assess how well the microbiome of a host population is represented by pools, and (ii) to compare variation of Drosophila microbiomes within and between populations. Taxon richness was increased in simulated pools, suggesting that pools paint a more comprehensive picture of the taxa associated with a host population. Furthermore, microbiome composition varied less between pools than between individuals, indicating that differences even out in pools. Variation in microbiome composition was larger between populations than between simulated pools from a single population, adding to the notion that there are population-specific effects on the Drosophila microbiome. Surprisingly, samples from individuals clustered into two groups, suggesting that there are yet unknown factors that affect the composition of natural fly-associated microbial communities and need further research.

RevDate: 2019-09-12
CmpDate: 2019-09-12

Bassene H, Niang EHA, Fenollar F, et al (2018)

16S Metagenomic Comparison of Plasmodium falciparum-Infected and Noninfected Anopheles gambiae and Anopheles funestus Microbiota from Senegal.

The American journal of tropical medicine and hygiene, 99(6):1489-1498.

In the context of the pre-elimination of malaria, biological control may provide an alternative or additional tool to current malaria control strategies. During their various stages of development, mosquitoes undergo subsequent changes in their associated microbiota, depending on their environment and nutritional status. Although Anopheles gambiae s.l. and Anopheles funestus are the two major malaria vectors in Senegal, the composition of their microbiota is not yet well known. In this study, we explored the microbiota of mosquitoes naturally infected or not by Plasmodium falciparum (Pf) using the 16S ribosomal RNA gene-based bacterial metagenomic approach. In both vector species, the microbiota was more diverse in Pf-infected samples than in the noninfected ones, although the total number of reads appeared to be higher in noninfected mosquitoes. Overall, the microbiota was different between the two vector species. Noteworthy, the bacterial microbiota was significantly different between Pf-positive and Pf-negative groups whatever the species, but was similar between individuals of the same infection status within a species. Overall, the phylum of Proteobacteria was the most predominant in both species, with bacteria of the genus Burkholderia outweighing the others in noninfected vectors. The presence of some specific bacterial species such as Asaia bogorensis, Enterobacter cloacae, Burkholderia fungorum, and Burkholderia cepacia was also observed in Pf-free samples only. These preliminary observations pave the way for further characterization of the mosquito microbiota to select promising bacterial candidates for potential use in an innovative approach to controlling malaria and overcoming the challenges to achieving a malaria-free world.

RevDate: 2019-09-12
CmpDate: 2019-09-12

Platzer A, Polzin J, Rembart K, et al (2018)

BioSankey: Visualization of Microbial Communities Over Time.

Journal of integrative bioinformatics, 15(4): pii:/j/jib.ahead-of-print/jib-2017-0063/jib-2017-0063.xml.

Metagenomics provides quantitative measurements for microbial species over time. To obtain a global overview of an experiment and to explore the full potential of a given dataset, intuitive and interactive visualization tools are needed. Therefore, we established BioSankey to visualize microbial species in microbiome studies over time as a Sankey diagram. These diagrams are embedded into a project-specific webpage which depends only on JavaScript and Google API to allow searches of interesting species without requiring a web server or connection to a database. BioSankey is a valuable tool to visualize different data elements from single or dual RNA-seq datasets and additionally enables a straightforward exchange of results among collaboration partners.

RevDate: 2019-09-09
CmpDate: 2019-09-09

Taylor-Brown A, Madden D, A Polkinghorne (2018)

Culture-independent approaches to chlamydial genomics.

Microbial genomics, 4(2):.

The expanding field of bacterial genomics has revolutionized our understanding of microbial diversity, biology and phylogeny. For most species, DNA extracted from culture material is used as the template for genome sequencing; however, the majority of microbes are actually uncultivable, and others, such as obligate intracellular bacteria, require laborious tissue culture to yield sufficient genomic material for sequencing. Chlamydiae are one such group of obligate intracellular microbes whose characterization has been hampered by this requirement. To circumvent these challenges, researchers have developed culture-independent sample preparation methods that can be applied to the sample directly or to genomic material extracted from the sample. These methods, which encompass both targeted [immunomagnetic separation-multiple displacement amplification (IMS-MDA) and sequence capture] and non-targeted approaches (host methylated DNA depletion-microbial DNA enrichment and cell-sorting-MDA), have been applied to a range of clinical and environmental samples to generate whole genomes of novel chlamydial species and strains. This review aims to provide an overview of the application, advantages and limitations of these targeted and non-targeted approaches in the chlamydial context. The methods discussed also have broad application to other obligate intracellular bacteria or clinical and environmental samples.

RevDate: 2019-09-11

Liang Y, Wang L, Wang Z, et al (2019)

Metagenomic Analysis of the Diversity of DNA Viruses in the Surface and Deep Sea of the South China Sea.

Frontiers in microbiology, 10:1951.

A metagenomic analysis of the viral community from five surface and five deep sea water (>2000 m below the surface, mbs) samples collected from the central basin of the South China Sea and adjacent Northwest Pacific Ocean during July-August 2017 was conducted herein. We builded up a South China Sea DNA virome (SCSV) dataset of 29,967 viral Operational Taxonomic Units (vOTUs), which is comparable to the viral populations from the original Tara Ocean and Malaspina expeditions. The most abundant and widespread viral populations were from the uncultivated viruses annotated from the viral metagenomics. Only 74 and 37 vOTUs have similarity with the reported genomes from the cultivated viruses and the single-virus genomics, respectively. The community structures of deep sea viromes in the SCSV were generally different from the surface viromes. The carbon flux and nutrients (PO4 and NOx) were related to the surface and deep sea viromes in the SCSV, respectively. In the SCSV, the annotated vOTUs could be affiliated to the cultivated viruses mainly including Pelagibacter (SAR11) phage HTVC010P, Prochlorococcus phages (P-GSP1, P-SSM4, and P-TIM68), Cyanophages (MED4-184 and MED4-117) and Mycobacterium phages (Sparky and Squirty). It indicated that phage infection to the SAR11 cluster may occur ubiquitously and has significant impacts on bathypelagic SAR11 communities in the deep sea. Meanwhile, as Prochlorococcus is prominently distributed in the euphotic ocean, the existence of their potential phages in the deep sea suggested the sedimentation mechanism might contribute to the formation of the deep sea viromes. Intriguingly, the presence of Mycobacterium phages only in the deep sea viromes, suggests inhabitance of endemic viral populations in the deep sea viromes in the SCSV. This study provided an insight of the viral community in the South China Sea and for the first time uncovered the deep sea viral diversity in the central basin of the South China Sea.

RevDate: 2019-09-10
CmpDate: 2019-09-10

Hu YL, Pang W, Huang Y, et al (2018)

The Gastric Microbiome Is Perturbed in Advanced Gastric Adenocarcinoma Identified Through Shotgun Metagenomics.

Frontiers in cellular and infection microbiology, 8:433.

Objective: Dysbiosis of gastric microbiota such as Helicobacter pylori plays a significant role in pathogenesis and progression of gastric cancer. Our aim was to evaluate the composition and functional effects of gastric microbiota in superficial gastritis (SG) and advanced gastric adenocarcinoma (GC). Methods: We carried out shotgun metagenomic sequencing on gastric wash samples from 6 patients with GC and 5 patients with SG. The taxonomic composition was profiled using MetaPhlAn2 and functional gene pathway was profiled using HUMAnN2. Differences in microbial composition and pathways between the two patient groups were assessed via LEfSe. Results: The gastric microbiota in GC patients was characterized by reduced species richness, enrichment of 13 bacterial taxa and depletion of 31 taxa (q < 0.05). The most representative taxa which were abundant in GC corresponded to the commensals or opportunistic pathogens that usually colonize the oral cavity, including genera Neisseria, Alloprevotella, and Aggregatibacter, species Streptococcus_mitis_oralis_pneumoniae and strain Porphyromonas_endodontalis.t_GCF_000174815. Each of the three GC-associated genera could separate GC from SG completely. In particular, Sphingobium yanoikuyae, a bacterium capable of degrading carcinogenic compounds, was depleted in GC. Functionally, pathways associated with the biosynthesis of lipopolysaccharide (LPS) and L-arginine were enriched in GC, whereas pathways involved in the fermentation of short chain fatty acids (SCFAs) and branched amino acid metabolism were more abundant in SG. Conclusions: Our results present new alterations in the gastric microbiome in patients with GC from a whole-genome perspective, suggesting that microbiome composition and function can be used for prognosis and diagnosis of GC.

RevDate: 2019-09-11
CmpDate: 2019-09-11

Kojadinovic-Sirinelli M, Villain A, Puppo C, et al (2018)

Exploring the microbiome of the "star" freshwater diatom Asterionella formosa in a laboratory context.

Environmental microbiology, 20(10):3601-3615.

Most of our knowledge on the mechanisms underlying diatom-bacterial interactions has been acquired through studies involving isolation of culturable partners. Here, we established a laboratory model of intermediate complexity between complex natural communities and laboratory pure culture models. We investigated the whole community formed by the freshwater diatom Asterionella formosa and its associated bacteria in a laboratory context, including both culturable and unculturable bacteria. Combining cellular and molecular approaches, we showed that in laboratory cultures, A. formosa microbiome was dynamic and comprised of numerous bacterial species (mainly Proteobacteria and Bacteroidetes). Using metagenomics, we explored several metabolic potentials present within the bacterial community. Our analyses suggested that bacteria were heterotrophic although a third of them (Alpha- and Beta-proteobacteria) could also be phototrophic. About 60% of the bacteria, phylogenetically diverse, could metabolize glycolate. The capacity to synthesize molecules such as B vitamins appeared unevenly distributed among bacteria. Altogether, our results brought insights into the bacterial diversity found in diatom-bacterial communities and hinted at metabolic interdependencies within the community that could result in diatom-bacterial and bacterial-bacterial interactions. The present work allowed us to explore the functional architecture of the bacterial community associated with A. formosa in culture and is complementary to field studies.

RevDate: 2019-09-09
CmpDate: 2019-09-09

Abia ALK, Alisoltani A, Ubomba-Jaswa E, et al (2019)

Microbial life beyond the grave: 16S rRNA gene-based metagenomic analysis of bacteria diversity and their functional profiles in cemetery environments.

The Science of the total environment, 655:831-841.

Recent studies have identified cemeteries as potential environmental reservoirs of multi-drug resistant pathogenic bacteria that could contaminate groundwater sources posing public health threats. However, these findings were based on the identification of culturable bacteria and at times not below burial grounds. Investigation on the bacterial diversity and functional profiles of bacterial communities above and below burial grounds in human cemeteries are few. The current study used high-throughput sequencing techniques to determine the bacterial composition and their associated functional profiles in cemetery soil samples collected at the surface and below burial ground in two South African cemeteries (Maitland Cemetery in Cape Town and Fontein Street Cemetery in Middelburg) to evaluate the potential health threat to surrounding populations through contamination of groundwater. Significant differences were observed between sample depths with the clustering of the surface (0 m) and the 2 m samples into separate groups. Pseudomonas and Corynebacterium were the most abundant genera across all samples. Pseudomonas and Rhodococcus were the dominant genera in the 2 m samples while Prauserella and Staphylococcus were dominant in the surface samples. The 2 m samples showed a lower alpha diversity but recorded higher proportions of human diseases functional classes compared to the surface samples. Human disease functional profiles revealed involvement, in infectious (cholera), neurodegenerative (Alzheimer's disease) cardiovascular (hypertrophic cardiomyopathy) immune system (Systemic lupus erythematosus) metabolic (Type I & II diabetes) diseases and cancer. Antibiotic resistance and antibiotics synthesis signatures were also identified. Thus, cemeteries could be potential sources of microbial and antibiotic pollution in groundwater, especially in areas with shallow water tables such as Maitland. Selection of sites for use as cemeteries should, therefore, require a proper understanding of the hydrogeological characteristics of the selected site. However, further studies are required to trace the actual movement of these pollutants into groundwater resources.

RevDate: 2019-09-09
CmpDate: 2019-09-09

Xiao P, Li C, Zhang Y, et al (2018)

Metagenomic Sequencing From Mosquitoes in China Reveals a Variety of Insect and Human Viruses.

Frontiers in cellular and infection microbiology, 8:364.

We collected 8,700 mosquitoes in three sites in China, which belonged to seven species. Their viromes were tested using metagenomic sequencing and bioinformatic analysis. The abundant viral sequences were detected and annotated belonging to more than 50 viral taxonomic families. The results were verified by PCR, followed by phylogenetic analysis. In the present study, we identified partial viral genes of dengue virus (DENV), a novel circovirus (CCV), densovirus (DNV), Japanese encephalitis virus (JEV), and Wuhan mosquito virus (WMV) in mosquitoes. Metagenomic analysis and PCR amplification revealed three DENV sequences, which were as homologous to the NS3 gene of DENV from Singapore isolated in 2005, with at least 91% nucleotide (nt) identity. Seven fragments of JEV encoding structural proteins were identified belonging to genotype I. They all shared high homology with structural protein genes of JEV isolated from Laos in 2009. The production of infectious virus particles of the newly isolated virus YunnanJEV2017-4 increased after passage from the BHK-21 cell line to the Vero cell line. Novel circovirus-related genes were identified and as being related to an unnamed gene of a mosquito circovirus (MCCV) sequence from the USA isolated in 2011, with at least 41% nt identity: this distant relationship suggests that the parent virus might belong to a novel circovirus genus. Additionally, numerous known viruses and some unknown viruses were also detected in mosquitoes from Yunnan province, China, which will be tested for propagation.

RevDate: 2019-09-09
CmpDate: 2019-09-09

Murakami T, Segawa T, Takeuchi N, et al (2018)

Metagenomic analyses highlight the symbiotic association between the glacier stonefly Andiperla willinki and its bacterial gut community.

Environmental microbiology, 20(11):4170-4183.

The glacier stonefly Andiperla willinki is the largest metazoan inhabiting the Patagonian glaciers. In this study, we analysed the gut microbiome of the aquatic nymphs by 16S rRNA gene amplicon and metagenomic sequencing. The bacterial gut community was consistently dominated by taxa typical of animal digestive tracts, such as Dysgonomonadaceae and Lachnospiraceae, as well as those generally indigenous to glacier environments, such as Polaromonas. Interestingly, the dominant Polaromonas phylotypes detected in the stonefly gut were almost never detected in the glacier surface habitat. Fluorescence in situ hybridization analysis revealed that the bacterial lineages typical of animal guts colonized the gut wall in a co-aggregated form, while Polaromonas cells were not included in the aggregates. Draft genomes of several dominant bacterial lineages were reconstructed from metagenomic datasets and indicated that the predominant Dysgonomonadaceae bacterium is capable of degrading various polysaccharides derived from host-ingested food, such as algae, and that other dominant bacterial lineages ferment saccharides liberated by the polysaccharide degradation. Our results suggest that the gut bacteria-host association in the glacier stonefly contributes to host nutrition as well as material cycles in the glacier environment.

RevDate: 2019-09-08

Chariton AA (2019)

Book review: Environmental DNA: For Biodiversity Research and Monitoring by Pierre Taberlet, Aurélie Bonin, Lucie Zinger and Eric Coissac.

Molecular ecology [Epub ahead of print].

Environmental DNA is reshaping the way we perform ecological research, with techniques such as metabarcoding increasingly used to capture complex biotic assemblages from myriad environmental matrices. Environmental DNA: For Biodiversity Research and Monitoring (2018) is a timely publication, delivering in-depth explanations of each step associated with metabarcoding research. While other eDNA techniques such as metagenomics and metatranscriptomics are covered in less detail, these chapters still provide an excellent introduction to these topics. Informative and clearly written, Environmental DNA: For Biodiversity Research and Monitoring provides the reader with the appropriate level of background information, theory and guidance to perform high quality eDNA research, and is an essential resource for both novice and well-seasoned molecular ecologist. This article is protected by copyright. All rights reserved.

RevDate: 2019-09-06
CmpDate: 2019-09-06

Cheng Y, Sibusiso L, Hou L, et al (2019)

Sargassum fusiforme fucoidan modifies the gut microbiota during alleviation of streptozotocin-induced hyperglycemia in mice.

International journal of biological macromolecules, 131:1162-1170.

Diabetes is a complicated endocrine and metabolic disorder, which has become an epidemic health issue worldwide. Fucoidan is extensively distributed in the brown algae and several marine invertebrates exhibiting diverse biological activities. In the present study, the physicochemical property of Sargassum fusiforme fucoidan (SFF) and its effects on streptozotocin (STZ)-induced diabetic mice and gut microbiota were investigated. Diabetes mice not only showed abnormal blood glucose, but also accompanied by multiple symptoms, such as gradual emaciation, decreased body weight, increased food and water intake. Compared with diabetic mice after 6-week treatment, administration of SFF significantly decreased the fasting blood glucose, diet and water intake. Furthermore, SFF attenuated the pathological change in the heart and liver, improved the liver function, and suppressed oxidative stress in STZ-induced diabetic mice. Simultaneously, SFF significantly altered the gut microbiota in the faeces of diabetic mice, decreased the relative abundances of the diabetes-related intestinal bacteria, which is a potential mechanism for relieving the symptoms of diabetes. Therefore, SFF might be considered as one of the promising complementary and alternative medicines for the management of diabetes mellitus in future.

RevDate: 2019-09-06
CmpDate: 2019-09-06

Ji X, Hou C, Zhang X, et al (2019)

Microbiome-metabolomic analysis of the impact of Zizyphus jujuba cv. Muzao polysaccharides consumption on colorectal cancer mice fecal microbiota and metabolites.

International journal of biological macromolecules, 131:1067-1076.

It is still uncertain whether the consumption of Zizyphus jujuba cv. Muzao polysaccharides (ZMP) alleviates colorectal cancer (CRC) through the gut microbiota. In this study, we investigated the mortality, colon length, inflammatory factors and cecal microbiota, metabolites of healthy and azoxymethane (AOM) and dextran sodium sulfate (DSS) in induced CRC mice, consuming ZMP. Fecal-microbiota composition was examined using 16S rDNA sequencing and fecal-metabolome profiles were evaluated by ultra-high performance liquid chromatograph mass spectrometry (UHPLC-MS). The results showed ZMP consumption prevented CRC mouse colon shortening, decreased their mortality, reduced pro-inflammatory cytokines, increased the concentration of total short-chain fatty acids (SCFAs) and modulated gut microbiota in their feces. ZMP also increased the richness of Bifidobacterium, Bacteroides and Lactobacillus. In addition, among 39 perturbed metabolites, carbohydrate and amino acid production were noticeably altered. Moreover, higher correlations were found between fluctuant gut microbiota and metabolites. These findings provide mechanistic insights into the impact of dietary Zizyphus jujuba cv. Muzao polysaccharides on host health.

RevDate: 2019-09-06
CmpDate: 2019-09-05

Boers SA, Jansen R, JP Hays (2019)

Understanding and overcoming the pitfalls and biases of next-generation sequencing (NGS) methods for use in the routine clinical microbiological diagnostic laboratory.

European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology, 38(6):1059-1070.

Recent advancements in next-generation sequencing (NGS) have provided the foundation for modern studies into the composition of microbial communities. The use of these NGS methods allows for the detection and identification of ('difficult-to-culture') microorganisms using a culture-independent strategy. In the field of routine clinical diagnostics however, the application of NGS is currently limited to microbial strain typing for epidemiological purposes only, even though the implementation of NGS for microbial community analysis may yield clinically important information. This lack of NGS implementation is due to many different factors, including issues relating to NGS method standardization and result reproducibility. In this review article, the authors provide a general introduction to the most widely used NGS methods currently available (i.e., targeted amplicon sequencing and shotgun metagenomics) and the strengths and weaknesses of each method is discussed. The focus of the publication then shifts toward 16S rRNA gene NGS methods, which are currently the most cost-effective and widely used NGS methods for research purposes, and are therefore more likely to be successfully implemented into routine clinical diagnostics in the short term. In this respect, the experimental pitfalls and biases created at each step of the 16S rRNA gene NGS workflow are explained, as well as their potential solutions. Finally, a novel diagnostic microbiota profiling platform ('MYcrobiota') is introduced, which was developed by the authors by taking into consideration the pitfalls, biases, and solutions explained in this article. The development of the MYcrobiota, and future NGS methodologies, will help pave the way toward the successful implementation of NGS methodologies into routine clinical diagnostics.

RevDate: 2019-09-06
CmpDate: 2019-09-06

Albert K, Rani A, DA Sela (2018)

The comparative genomics of Bifidobacterium callitrichos reflects dietary carbohydrate utilization within the common marmoset gut.

Microbial genomics, 4(6):.

Bifidobacterium is a diverse genus of anaerobic, saccharolytic bacteria that colonize many animals, notably humans and other mammals. The presence of these bacteria in the gastrointestinal tract represents a potential coevolution between the gut microbiome and its mammalian host mediated by diet. To study the relationship between bifidobacterial gut symbionts and host nutrition, we analyzed the genome of two bifidobacteria strains isolated from the feces of a common marmoset (Callithrix jacchus), a primate species studied for its ability to subsist on host-indigestible carbohydrates. Whole genome sequencing identified these isolates as unique strains of Bifidobacterium callitrichos. All three strains, including these isolates and the previously described type strain, contain genes that may enable utilization of marmoset dietary substrates. These include genes predicted to contribute to galactose, arabinose, and trehalose metabolic pathways. In addition, significant genomic differences between strains suggest that bifidobacteria possess distinct roles in carbohydrate metabolism within the same host. Thus, bifidobacteria utilize dietary components specific to their host, both humans and non-human primates alike. Comparative genomics suggests conservation of possible coevolutionary relationships within the primate clade.

RevDate: 2019-08-29

Pini Prato A, Bartow-McKenney C, Hudspeth K, et al (2019)

A Metagenomics Study on Hirschsprung's Disease Associated Enterocolitis: Biodiversity and Gut Microbial Homeostasis Depend on Resection Length and Patient's Clinical History.

Frontiers in pediatrics, 7:326.

Objectives: Since 2010, several researches demonstrated that microbiota dynamics correlate and can even predispose to Hirschsprung (HSCR) associated enterocolitis (HAEC). This study aims at assessing the structure of the microbiota of HSCR patients in relation to extent of aganglionosis and HAEC status. Methods: All consecutive HSCR patients admitted to Gaslini Institute (Genova, Italy) between May 2012 and November 2014 were enrolled. Institutional review board (IRB) approval was obtained. Stools were sampled and 16S rDNA V3-V4 regions were sequenced using the Illumina-MiSeq. Taxonomy assignments were performed using QIIME RDP. Alpha diversity indexes were analyzed by Shannon and Simpson Indexes, and Phylogenetic Diversity. Results: We enrolled 20 patients. Male to female ratio was 4:1. Six patients suffered from Total Colonic Aganglionosis (TCSA). Considering sample site (i.e., extent of aganglionosis), we confirmed the known relationship between sample site and both biodiversity and composition of intestinal microbiota. Patients with TCSA showed lower biodiversity and increased Proteobacteria/Bacteroidetes relative abundance ratio. When addressing biodiversity, composition and dynamics of TCSA patients we could not find any significant relationship with regard to HAEC occurrences. Conclusions: The composition of HAEC predisposing microbiota is specific to each patient. We could confirm that total colon resections can change the composition of intestinal microbiota and to dramatically reduce microbial diversity. The subsequent reduction of system robustness could expose TCSA patients to environmental microbes that might not be part of the normal microbiota. Future long-term studies should investigate both patients and their family environment, as well as their disease history.

RevDate: 2019-08-29

Wu B, Hussain M, Zhang W, et al (2019)

Current insights into fungal species diversity and perspective on naming the environmental DNA sequences of fungi.

Mycology, 10(3):127-140 pii:1614106.

The global bio-diversity of fungi has been extensively investigated and their species number has been estimated. Notably, the development of molecular phylogeny has revealed an unexpected fungal diversity and utilisation of culture-independent approaches including high-throughput amplicon sequencing has dramatically increased number of fungal operational taxonomic units. A number of novel taxa including new divisions, classes, orders and new families have been established in last decade. Many cryptic species were identified by molecular phylogeny. Based on recently generated data from culture-dependent and -independent survey on same samples, the fungal species on the earth were estimated to be 12 (11.7-13.2) million compared to 2.2-3.8 million species recently estimated by a variety of the estimation techniques. Moreover, it has been speculated that the current use of high-throughput sequencing techniques would reveal an even higher diversity than our current estimation. Recently, the formal classification of environmental sequences and permission of DNA sequence data as fungal names' type were proposed but strongly objected by the mycologist community. Surveys on fungi in unusual niches have indicated that many previously regarded "unculturable fungi" could be cultured on certain substrates under specific conditions. Moreover, the high-throughput amplicon sequencing, shotgun metagenomics and a single-cell genomics could be a powerful means to detect novel taxa. Here, we propose to separate the fungal types into physical type based on specimen, genome DNA (gDNA) type based on complete genome sequence of culturable and uncluturable fungal specimen and digital type based on environmental DNA sequence data. The physical and gDNA type should have priority, while the digital type can be temporal supplementary before the physical type and gDNA type being available. The fungal name based on the "digital type" could be assigned as the "clade" name + species name. The "clade" name could be the name of genus, family or order, etc. which the sequence of digital type affiliates to. Facilitating future cultivation efforts should be encouraged. Also, with the advancement in knowledge of fungi inhabiting various environments mostly because of rapid development of new detection technologies, more information should be expected for fungal diversity on our planet.

RevDate: 2019-08-24

Loit K, Adamson K, Bahram M, et al (2019)

Relative Performance of MinION (Oxford Nanopore Technologies) vs. Sequel (Pacific Biosciences) Third-Generation Sequencing Instruments in Identification of Agricultural and Forest Fungal Pathogens.

Applied and environmental microbiology pii:AEM.01368-19 [Epub ahead of print].

Culture-based molecular identification methods have revolutionized detection of pathogens, yet these methods are slow and may yield inconclusive results from environmental materials. The second-generation sequencing tools have much improved precision and sensitivity of detection, but these analyses are costly and may take several days to months. Of the third-generation sequencing techniques, the portable MinION device (Oxford Nanopore Technologies) has received much attention because of its small size and possibility of rapid analysis at reasonable cost. Here, we compare the relative performance of two third-generation sequencing instruments, MinION and Sequel (Pacific Biosciences) in identification and diagnostics of fungal and oomycete pathogens from conifer (Pinaceae spp.) needles and potato (Solanum tuberosum) leaves and tubers. We demonstrate that Sequel instrument is efficient for metabarcoding of complex samples, whereas MinION is not suited for this purpose due to the high error rate and multiple biases. However, we find that MinION can be utilized for rapid and accurate identification of dominant pathogenic organisms and other associated organisms from plant tissues following both amplicon-based and PCR-free metagenomics approaches. Using the metagenomics approach with shortened DNA extraction and incubation times, we performed the entire MinION workflow from sample preparation through DNA extraction, sequencing, bioinformatics and interpretation in two and half hours. We advocate the use of MinION for rapid diagnostics of pathogens and potentially other organisms, but care needs to be taken to control or account for multiple potential technical biases.IMPORTANCE Microbial pathogens cause enormous losses to agriculture and forestry, but current combined culturing- and molecular identification-based detection methods are too slow for rapid identification and application of countermeasures. Here we develop new and rapid protocols for Oxford Nanopore MinION-based third-generation diagnostics of plant pathogens that greatly improves the speed of diagnostics. However, due to high error rate and technical biases in MinION, the Pacific BioSciences Sequel platform is more useful for in-depth amplicon-based biodiversity monitoring (metabarcoding) from complex environmental samples.

RevDate: 2019-08-25

Vavourakis CD, Mehrshad M, Balkema C, et al (2019)

Metagenomes and metatranscriptomes shed new light on the microbial-mediated sulfur cycle in a Siberian soda lake.

BMC biology, 17(1):69 pii:10.1186/s12915-019-0688-7.

BACKGROUND: The planetary sulfur cycle is a complex web of chemical reactions that can be microbial-mediated or can occur spontaneously in the environment, depending on the temperature and pH. Inorganic sulfur compounds can serve as energy sources for specialized prokaryotes and are important substrates for microbial growth in general. Here, we investigate dissimilatory sulfur cycling in the brine and sediments of a southwestern Siberian soda lake characterized by an extremely high pH and salinity, combining meta-omics analyses of its uniquely adapted highly diverse prokaryote communities with biogeochemical profiling to identify key microbial players and expand our understanding of sulfur cycling under haloalkaline conditions.

RESULTS: Peak microbial activity was found in the top 4 cm of the sediments, a layer with a steep drop in oxygen concentration and redox potential. The majority of sulfur was present as sulfate or iron sulfide. Thiosulfate was readily oxidized by microbes in the presence of oxygen, but oxidation was partially inhibited by light. We obtained 1032 metagenome-assembled genomes, including novel population genomes of characterized colorless sulfur-oxidizing bacteria (SOB), anoxygenic purple sulfur bacteria, heterotrophic SOB, and highly active lithoautotrophic sulfate reducers. Surprisingly, we discovered the potential for nitrogen fixation in a new genus of colorless SOB, carbon fixation in a new species of phototrophic Gemmatimonadetes, and elemental sulfur/sulfite reduction in the "Candidatus Woesearchaeota." Polysulfide/thiosulfate and tetrathionate reductases were actively transcribed by various (facultative) anaerobes.

CONCLUSIONS: The recovery of over 200 genomes that encoded enzymes capable of catalyzing key reactions in the inorganic sulfur cycle indicates complete cycling between sulfate and sulfide at moderately hypersaline and extreme alkaline conditions. Our results suggest that more taxonomic groups are involved in sulfur dissimilation than previously assumed.

RevDate: 2019-08-03

Cowan DA, Hopkins DW, Jones BE, et al (2019)

Microbiomics of Namib Desert habitats.

Extremophiles : life under extreme conditions pii:10.1007/s00792-019-01122-7 [Epub ahead of print].

The Namib Desert is one of the world's only truly coastal desert ecosystem. Until the end of the 1st decade of the twenty-first century, very little was known of the microbiology of this southwestern African desert, with the few reported studies being based solely on culture-dependent approaches. However, from 2010, an intense research program was undertaken by researchers from the University of the Western Cape Institute for Microbial Biotechnology and Metagenomics, and subsequently the University of Pretoria Centre for Microbial Ecology and Genomics, and their collaborators, led to a more detailed understanding of the ecology of the indigenous microbial communities in many Namib Desert biotopes. Namib Desert soils and the associated specialized niche communities are inhabited by a wide array of prokaryotic, lower eukaryotic and virus/phage taxa. These communities are highly heterogeneous on both small and large spatial scales, with community composition impacted by a range of macro- and micro-environmental factors, from water regime to soil particle size. Community functionality is also surprisingly non-homogeneous, with some taxa retaining functionality even under hyper-arid soil conditions, and with subtle changes in gene expression and phylotype abundances even on diel timescales. Despite the growing understanding of the structure and function of Namib Desert microbiomes, there remain enormous gaps in our knowledge. We have yet to quantify many of the processes in these soil communities, from regional nutrient cycling to community growth rates. Despite the progress that has been made, we still have little knowledge of either the role of phages in microbial community dynamics or inter-species interactions. Furthermore, the intense research efforts of the past decade have highlighted the immense scope for future microbiological research in this dynamic, enigmatic and charismatic region of Africa.

RevDate: 2019-08-18

Sutela S, Poimala A, EJ Vainio (2019)

Viruses of fungi and oomycetes in the soil environment.

FEMS microbiology ecology, 95(9):.

Soils support a myriad of organisms hosting highly diverse viromes. In this minireview, we focus on viruses hosted by true fungi and oomycetes (members of Stamenopila, Chromalveolata) inhabiting bulk soil, rhizosphere and litter layer, and representing different ecological guilds, including fungal saprotrophs, mycorrhizal fungi, mutualistic endophytes and pathogens. Viruses infecting fungi and oomycetes are characterized by persistent intracellular nonlytic lifestyles and transmission via spores and/or hyphal contacts. Almost all fungal and oomycete viruses have genomes composed of single-stranded or double-stranded RNA, and recent studies have revealed numerous novel viruses representing yet unclassified family-level groups. Depending on the virus-host combination, infections can be asymptomatic, beneficial or detrimental to the host. Thus, mycovirus infections may contribute to the multiplex interactions of hosts, therefore likely affecting the dynamics of fungal communities required for the functioning of soil ecosystems. However, the effects of fungal and oomycete viruses on soil ecological processes are still mostly unknown. Interestingly, new metagenomics data suggest an extensive level of horizontal virus transfer between plants, fungi and insects.

RevDate: 2019-08-02

Raimondi S, Amaretti A, Gozzoli C, et al (2019)

Longitudinal Survey of Fungi in the Human Gut: ITS Profiling, Phenotyping, and Colonization.

Frontiers in microbiology, 10:1575.

The fungal component of the intestinal microbiota of eight healthy subjects was studied over 12 months using metagenome survey and culture-based approaches. Aspergillus, Candida, Debaryomyces, Malassezia, Penicillium, Pichia, and Saccharomyces were the most recurrent and/or dominant fungal genera, according to metagenomic analysis. The biodiversity of fungal communities was lower and characterized by greater unevenness, when compared to bacterial microbiome. The dissimilarities both among subjects and over the time within the same subject suggested that most of the fungi passed through the gastro-intestinal tract (GIT) without becoming stable colonizers. Certain genera, such as Aspergillus and Penicillium, were isolated in a minority of cases, although they recurred abundantly and frequently in the metagenomics survey, likely being environmental or food-borne fungi that do not inhabit the GIT. Candida genus was recurrently detected. Candida albicans isolates dominated among the cultivable mycobiota and longitudinally persisted, likely as commensals inhabiting the intestine or regularly reaching it from Candida-colonized districts, such as the oral cavity. Other putative colonizers belonged to Candida zeylanoides, Geotrichum candidum, and Rhodotorula mucilaginosa, with persisting biotypes being identified. Phenotyping of fungal isolates indicated that C. albicans adhered to human epithelial cells more efficiently and produced greater amounts of biofilm in vitro than non-albicans Candida (NAC) and non-Candida fungi (NCF). The C. albicans isolates also induced the highest release of HBD-2 by human epithelial cells, further differing from NAC and NCF. Nine representative isolates were administered to mice to evaluate the ability to colonize the intestine. Only two out of three C. albicans strains persisted in stools of animals 2 weeks after the end of the oral administration, whereas NAC and NCF did not. These results confirm the allochthonous nature of most the intestinal fungi, while C. albicans appears to be commonly involved in stable colonization. A combination of specific genetic features in the microbe and in the host likely allow colonization from fungi normally present solely as passengers. It remains to be established if other species identified as potential colonizers, in addition to Candida, are true inhabitants of the GIT or rather reach the intestine spreading from other body districts.

RevDate: 2019-07-26

Praeg N, Pauli H, P Illmer (2019)

Microbial Diversity in Bulk and Rhizosphere Soil of Ranunculus glacialis Along a High-Alpine Altitudinal Gradient.

Frontiers in microbiology, 10:1429.

Serving as "natural laboratories", altitudinal gradients can be used to study changes in the distribution of microorganisms in response to changing environmental conditions that typically occur over short geographical distances. Besides, rhizosphere zones of plants are known to be hot-spots for microbial diversity and to contain different microbial communities when compared with surrounding bulk soil. To discriminate the effects of altitude and plants, we investigated the microbial communities in the rhizosphere of Ranunculus glacialis and bulk soil along a high-alpine altitudinal gradient (2,600-3,400 m a.s.l.). The research area of this study was Mount (Mt.) "Schrankogel" in the Central Alps of Tyrol (Austria). Our results point to significantly different microbial diversities and community compositions in the different altitudinal belts. In the case of prokaryotes, environmental parameters could explain 41% of the total variation of soil communities, with pH and temperature being the strongest influencing factors. Comparing the effects derived from fraction (bulk vs. rhizosphere soil) and environmental factors, the effects of the roots of R. glacialis accounted for about one third of the explained variation. Fungal communities on the other hand were nearly exclusively influenced by environmental parameters accounting for 37.4% of the total variation. Both, for altitudinal zones as well as for bulk and rhizosphere fractions a couple of very specific biomarker taxa could be identified. Generally, the patterns of abundance of several taxa did not follow a steady increased or decreased trend along the altitudinal gradient but in many cases a maximal or minimal occurrence was established at mid-altitudes (3,000-3,100 m). This mid-altitudinal zone is a transition zone (the so-called alpine-nival ecotone) between the (lower) alpine grassland/tundra zone and the (upper) sparsely vegetated nival zone and was shown to correspond with the summer snow line. Climate change and the associated increase in temperature will shift this transition zone and thus, might also shift the described microbial patterns and biomarkers.

RevDate: 2019-07-25

Thomas SC, Tamadonfar KO, Seymour CO, et al (2019)

Position-Specific Metabolic Probing and Metagenomics of Microbial Communities Reveal Conserved Central Carbon Metabolic Network Activities at High Temperatures.

Frontiers in microbiology, 10:1427.

Temperature is a primary driver of microbial community composition and taxonomic diversity; however, it is unclear to what extent temperature affects characteristics of central carbon metabolic pathways (CCMPs) at the community level. In this study, 16S rRNA gene amplicon and metagenome sequencing were combined with 13C-labeled metabolite probing of the CCMPs to assess community carbon metabolism along a temperature gradient (60-95°C) in Great Boiling Spring, NV. 16S rRNA gene amplicon diversity was inversely proportional to temperature, and Archaea were dominant at higher temperatures. KO richness and diversity were also inversely proportional to temperature, yet CCMP genes were similarly represented across the temperature gradient and many individual metagenome-assembled genomes had complete pathways. In contrast, genes encoding cellulosomes and many genes involved in plant matter degradation and photosynthesis were absent at higher temperatures. In situ13C-CO2 production from labeled isotopomer pairs of glucose, pyruvate, and acetate suggested lower relative oxidative pentose phosphate pathway activity and/or fermentation at 60°C, and a stable or decreased maintenance energy demand at higher temperatures. Catabolism of 13C-labeled citrate, succinate, L-alanine, L-serine, and L-cysteine was observed at 85°C, demonstrating broad heterotrophic activity and confirming functioning of the TCA cycle. Together, these results suggest that temperature-driven losses in biodiversity and gene content in geothermal systems may not alter CCMP function or maintenance energy demands at a community level.

RevDate: 2019-07-26

Chen J, McIlroy SE, Archana A, et al (2019)

A pollution gradient contributes to the taxonomic, functional, and resistome diversity of microbial communities in marine sediments.

Microbiome, 7(1):104 pii:10.1186/s40168-019-0714-6.

BACKGROUND: Coastal marine environments are one of the most productive ecosystems on Earth. However, anthropogenic impacts exert significant pressure on coastal marine biodiversity, contributing to functional shifts in microbial communities and human health risk factors. However, relatively little is known about the impact of eutrophication-human-derived nutrient pollution-on the marine microbial biosphere.

RESULTS: Here, we tested the hypothesis that benthic microbial diversity and function varies along a pollution gradient, with a focus on human pathogens and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG annotation revealed that zinc, lead, total volatile solids, and ammonia nitrogen were correlated with microbial diversity and function. We propose several microbes, including Planctomycetes and sulfate-reducing microbes as candidates to reflect pollution concentration. Annotation of antibiotic resistance genes showed that the highest abundance of efflux pumps was found at the most polluted site, corroborating the relationship between pollution and human health risk factors. This result suggests that sediments at polluted sites harbor microbes with a higher capacity to reduce intracellular levels of antibiotics, heavy metals, or other environmental contaminants.

CONCLUSIONS: Our findings suggest a correlation between pollution and the marine sediment microbiome and provide insight into the role of high-turnover microbial communities as well as potential pathogenic organisms as real-time indicators of water quality, with implications for human health and demonstrate the inner functional shifts contributed by the microcommunities.

RevDate: 2019-07-23

Bengtsson-Palme J, Milakovic M, Švecová H, et al (2019)

Industrial wastewater treatment plant enriches antibiotic resistance genes and alters the structure of microbial communities.

Water research, 162:437-445.

Antibiotic resistance is an emerging global health crisis, driven largely by overuse and misuse of antibiotics. However, there are examples in which the production of these antimicrobial agents has polluted the environment with active antibiotic residues, selecting for antibiotic resistant bacteria and the genes they carry. In this work, we have used shotgun metagenomics to investigate the taxonomic structure and resistance gene composition of sludge communities in a treatment plant in Croatia receiving wastewater from production of the macrolide antibiotic azithromycin. We found that the total abundance of antibiotic resistance genes was three times higher in sludge from the treatment plant receiving wastewater from pharmaceutical production than in municipal sludge from a sewage treatment plant in Zagreb. Surprisingly, macrolide resistance genes did not have higher abundances in the industrial sludge, but genes associated with mobile genetic elements such as integrons had. We conclude that at high concentrations of antibiotics, selection may favor taxonomic shifts towards intrinsically resistant species or strains harboring chromosomal resistance mutations rather than acquisition of mobile resistance determinants. Our results underscore the need for regulatory action also within Europe to avoid release of antibiotics into the environment.

RevDate: 2019-08-07

Ji Y, Huotari T, Roslin T, et al (2019)

SPIKEPIPE: A metagenomic pipeline for the accurate quantification of eukaryotic species occurrences and intraspecific abundance change using DNA barcodes or mitogenomes.

Molecular ecology resources [Epub ahead of print].

The accurate quantification of eukaryotic species abundances from bulk samples remains a key challenge for community ecology and environmental biomonitoring. We resolve this challenge by combining shotgun sequencing, mapping to reference DNA barcodes or to mitogenomes, and three correction factors: (a) a percent-coverage threshold to filter out false positives, (b) an internal-standard DNA spike-in to correct for stochasticity during sequencing, and (c) technical replicates to correct for stochasticity across sequencing runs. The SPIKEPIPE pipeline achieves a strikingly high accuracy of intraspecific abundance estimates (in terms of DNA mass) from samples of known composition (mapping to barcodes R2 = .93, mitogenomes R2 = .95) and a high repeatability across environmental-sample replicates (barcodes R2 = .94, mitogenomes R2 = .93). As proof of concept, we sequence arthropod samples from the High Arctic, systematically collected over 17 years, detecting changes in species richness, species-specific abundances, and phenology. SPIKEPIPE provides cost-efficient and reliable quantification of eukaryotic communities.

RevDate: 2019-08-01

Taubert M, Grob C, Crombie A, et al (2019)

Communal metabolism by Methylococcaceae and Methylophilaceae is driving rapid aerobic methane oxidation in sediments of a shallow seep near Elba, Italy.

Environmental microbiology [Epub ahead of print].

The release of abiotic methane from marine seeps into the atmosphere is a major source of this potent greenhouse gas. Methanotrophic microorganisms in methane seeps use methane as carbon and energy source, thus significantly mitigating global methane emissions. Here, we investigated microbial methane oxidation at the sediment-water interface of a shallow marine methane seep. Metagenomics and metaproteomics, combined with 13 C-methane stable isotope probing, demonstrated that various members of the gammaproteobacterial family Methylococcaceae were the key players for methane oxidation, catalysing the first reaction step to methanol. We observed a transfer of carbon to methanol-oxidizing methylotrophs of the betaproteobacterial family Methylophilaceae, suggesting an interaction between methanotrophic and methylotrophic microorganisms that allowed for rapid methane oxidation. From our microcosms, we estimated methane oxidation rates of up to 871 nmol of methane per gram sediment per day. This implies that more than 50% of methane at the seep is removed by microbial oxidation at the sediment-water interface, based on previously reported in situ methane fluxes. The organic carbon produced was further assimilated by different heterotrophic microbes, demonstrating that the methane-oxidizing community supported a complex trophic network. Our results provide valuable eco-physiological insights into this specialized microbial community performing an ecosystem function of global relevance.

RevDate: 2019-07-16

Fernández-Correa I, Truchado DA, Gomez-Lucia E, et al (2019)

A novel group of avian astroviruses from Neotropical passerine birds broaden the diversity and host range of Astroviridae.

Scientific reports, 9(1):9513 pii:10.1038/s41598-019-45889-3.

Metagenomics is helping to expand the known diversity of viruses, especially of those with poorly studied hosts in remote areas. The Neotropical region harbors a considerable diversity of avian species that may play a role as both host and short-distance vectors of unknown viruses. Viral metagenomics of cloacal swabs from 50 Neotropical birds collected in French Guiana revealed the presence of four complete astrovirus genomes. They constitute an early diverging novel monophyletic clade within the Avastrovirus phylogeny, representing a putative new astrovirus species (provisionally designated as Avastrovirus 5) according to the International Committee on Taxonomy of Viruses (ICTV) classification criteria. Their genomic organization shares some characteristics with Avastrovirus but also with Mamastrovirus. The pan-astrovirus RT-PCR analysis of the cloacal samples of 406 wild Neotropical birds showed a community-level prevalence of 4.9% (5.1% in passerines, the highest described so far in this order of birds). By screening birds of a remote region, we expanded the known host range of astroviruses to the avian families Cardinalidae, Conopophagidae, Furnariidae, Thamnophilidae, Turdidae and Tyrannidae. Our results provide important first insights into the unexplored viral communities, the ecology, epidemiology and features of host-pathogen interactions that shape the evolution of avastroviruses in a remote Neotropical rainforest.

RevDate: 2019-07-02

Pereira O, Hochart C, Auguet JC, et al (2019)

Genomic ecology of Marine Group II, the most common marine planktonic Archaea across the surface ocean.

MicrobiologyOpen [Epub ahead of print].

Planktonic Archaea have been detected in all the world's oceans and are found from surface waters to the deep sea. The two most common Archaea phyla are Thaumarchaeota and Euryarchaeota. Euryarchaeota are generally more common in surface waters, but very little is known about their ecology and their potential metabolisms. In this study, we explore the genomic ecology of the Marine Group II (MGII), the main marine planktonic Euryarchaeota, and test if it is composed of different ecologically relevant units. We re-analyzed Tara Oceans metagenomes from the photic layer and the deep ocean by annotating sequences against a custom MGII database and by mapping gene co-occurrences. Our data provide a global view of the distribution of Euryarchaeota, and more specifically of MGII subgroups, and reveal their association to a number of gene-coding sequences. In particular, we show that MGII proteorhodopsins were detected in both the surface and the deep chlorophyll maximum layer and that different clusters of these light harvesting proteins were present. Our approach helped describing the set of genes found together with specific MGII subgroups. We could thus define genomic environments that could theoretically describe ecologically meaningful units and the ecological niche that they occupy.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Wang L, Li Z, Liu R, et al (2019)

Bacterial Diversity in Soybean Rhizosphere Soil at Seedling and Mature Stages.

Polish journal of microbiology, 68(2):281-284.

Changes in the structural diversity of bacterial communities in soybean rhizospheres play important roles in plant growth and crop productivity. However, there are only a few studies on different soybean growth stages. Here, we investigated the changes in the bacterial community of soybean rhizosphere soil at two stages using Illumina high-throughput sequencing. The results showed that the bacterial abundance and diversity in the seeding stage were higher than those in the mature stage and that the diversity changed significantly. Actinobacteria, Acidobacteria, and Proteobacteria were the dominant bacteria in the soybean rhizosphere soil. Additionally, changes in Actinobacteria and Proteobacteria abundances showed opposite trends.

Changes in the structural diversity of bacterial communities in soybean rhizospheres play important roles in plant growth and crop productivity. However, there are only a few studies on different soybean growth stages. Here, we investigated the changes in the bacterial community of soybean rhizosphere soil at two stages using Illumina high-throughput sequencing. The results showed that the bacterial abundance and diversity in the seeding stage were higher than those in the mature stage and that the diversity changed significantly. Actinobacteria, Acidobacteria, and Proteobacteria were the dominant bacteria in the soybean rhizosphere soil. Additionally, changes in Actinobacteria and Proteobacteria abundances showed opposite trends.

RevDate: 2019-06-28

Goss-Souza D, Mendes LW, Rodrigues JLM, et al (2019)

Ecological Processes Shaping Bulk Soil and Rhizosphere Microbiome Assembly in a Long-Term Amazon Forest-to-Agriculture Conversion.

Microbial ecology pii:10.1007/s00248-019-01401-y [Epub ahead of print].

Forest-to-agriculture conversion has been identified as a major threat to soil biodiversity and soil processes resilience, although the consequences of long-term land use change to microbial community assembly and ecological processes have been often neglected. Here, we combined metagenomic approach with a large environmental dataset, to (i) identify the microbial assembly patterns and, (ii) to evaluate the ecological processes governing microbial assembly, in bulk soil and soybean rhizosphere, along a long-term forest-to-agriculture conversion chronosequence, in Eastern Amazon. We hypothesized that (i) microbial communities in bulk soil and rhizosphere have different assembly patterns and (ii) the weight of the four ecological processes governing assembly differs between bulk soil and rhizosphere and along the chronosequence in the same fraction. Community assembly in bulk soil fitted most the zero-sum multinomial (ZSM) neutral-based model, regardless of time. Low to intermediate dispersal was observed. Decreasing influence of abiotic factors was counterbalanced by increasing influence of biotic factors, as the chronosequence advanced. Undominated ecological processes of dispersal limitation and variable selection governing community assembly were observed in this soil fraction. For soybean rhizosphere, community assembly fitted most the lognormal niche-based model in all chronosequence areas. High dispersal and an increasing influence of abiotic factors coupled with a decreasing influence of biotic factors were found along the chronosequence. Thus, we found a dominant role of dispersal process governing microbial assembly with a secondary effect of homogeneous selection process, mainly driven by decreasing aluminum and increased cations saturation in soil solution, due to long-term no-till cropping. Together, our results indicate that long-term no-till lead community abundances in bulk soil to be in a transient and conditional state, while for soybean rhizosphere, community abundances reach a periodic and permanent distribution state. Dominant dispersal process in rhizosphere, coupled with homogeneous selection, brings evidences that soybean root system selects microbial taxa via trade-offs in order to keep functional resilience of soil processes.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Tamaki H (2019)

Cultivation Renaissance in the Post-Metagenomics Era: Combining the New and Old.

Microbes and environments, 34(2):117-120.

RevDate: 2019-08-26
CmpDate: 2019-08-26

Costa M, JS Weese (2019)

Methods and basic concepts for microbiota assessment.

Veterinary journal (London, England : 1997), 249:10-15.

There has been a marked increase in interest regarding complex microbial populations in recent years. The methodology used for microbial assessment has drastically changed over the last two decades and continues to advance at a rapid pace. Culture-based studies have been superseded by those based upon molecular methods, which have been largely used to discover new species and to better characterize complex communities, mainly driven by the advances in DNA sequencing, termed 'next generation sequencing'. These methodologies have allowed for a better understanding of the relationship between hosts and their microbiotas, which have important roles in health maintenance and in the pathophysiology of wide ranging conditions such as obesity, diabetes, allergic diseases and even behavioural changes. While most widely used in humans, these approaches are now commonly used in veterinary research, with increasing interest in direct clinical applications. As these methods provide novel insights that will constitute the basis for the development of new therapeutic and prevention strategies, and as commercial efforts to offer microbiota assessment as a clinical tool expand, it is essential for researchers and clinical veterinarians to understand and have the tools to be able to interpret research performed in this new fascinating field. The objective of this review is to describe some of the most common methods for characterization of microbial communities and to provide an overview of the basic concepts necessary for good interpretation of the research performed in this field.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Kunath BJ, Minniti G, Skaugen M, et al (2019)

Metaproteomics: Sample Preparation and Methodological Considerations.

Advances in experimental medicine and biology, 1073:187-215.

Meta-omic techniques have progressed rapidly in the past decade and are frequently used in microbial ecology to study microorganisms in their natural ecosystems independent from culture restrictions. Metaproteomics, in combination with metagenomics, enables quantitative assessment of expressed proteins and pathways from individual members of the consortium. Together, metaproteomics and metagenomics can provide a detailed understanding of which organisms occupy specific metabolic niches, how they interact, and how they utilize nutrients, and these insights can be obtained directly from environmental samples. Here, we outline key aspects of sample preparation, database generation, and other methodological considerations that are required for successful quantitative metaproteomic analyses and we describe case studies on the integration with metagenomics for enhanced functional output.

RevDate: 2019-07-24
CmpDate: 2019-07-22

Joishy TK, Dehingia M, MR Khan (2019)

Bacterial diversity and metabolite profiles of curd prepared by natural fermentation of raw milk and back sloping of boiled milk.

World journal of microbiology & biotechnology, 35(7):102 pii:10.1007/s11274-019-2677-y.

Preparation of curd vary worldwide due to which its taste, texture and impact on human health also differ. In Assam, curd prepared from raw milk (RMC) is preferred over curd prepared from boiled milk (BMC), a tradition believed to have originated from the Mongoloid customs. Microbial diversity of raw milk (RM), boiled milk (BM), RMC and BMC collected from three farms were investigated by culture dependent and independent techniques. Additionally, metabolite profiles of RMC and BMC were studied by gas chromatography and mass spectroscopy. A total of 59 bacterial isolates were identified from the four different dairy products. In RM, lactic acid bacteria such as Lactococcus, Enterococcus, Lactobacillus and Leuconostoc were obtained along with the environmental bacteria like Bacillus, Staphylococcus, Acetobacter, Chryseobacterium, Streptococcus, Acinetobacter, Kocuria, Klebsiella and Macrococcus. Additionally, Prevotella, Oscillospira, Phascolarctobacterium and Akkermansia were also detected in BM by culture independent technique. In RMC and BMC, Lactococcus, Leuconostoc and Lactobacillus were prevalent. RM and RMC shared Enterococcus, Lactococcus, Streptococcus and Acinetobacter as common bacterial genera. However, no bacterial genus was common in BM and BMC. The correlation analysis revealed that Lactobacillus was negatively correlated to other bacterial genera. Oligotyping analysis revealed that Lactobacillus brevis and L.fermentum were abundant in RMC and BMC, respectively. In metabolomic study, ascorbic acid, dodecanoic acid and hexadecanoic acid were found to be significantly higher in RMC. Presence of different types of probiotics in these curds samples opens a new avenue to understand their effects on human health.

RevDate: 2019-08-07
CmpDate: 2019-08-07

Lo C, R Marculescu (2019)

MetaNN: accurate classification of host phenotypes from metagenomic data using neural networks.

BMC bioinformatics, 20(Suppl 12):314 pii:10.1186/s12859-019-2833-2.

BACKGROUND: Microbiome profiles in the human body and environment niches have become publicly available due to recent advances in high-throughput sequencing technologies. Indeed, recent studies have already identified different microbiome profiles in healthy and sick individuals for a variety of diseases; this suggests that the microbiome profile can be used as a diagnostic tool in identifying the disease states of an individual. However, the high-dimensional nature of metagenomic data poses a significant challenge to existing machine learning models. Consequently, to enable personalized treatments, an efficient framework that can accurately and robustly differentiate between healthy and sick microbiome profiles is needed.

RESULTS: In this paper, we propose MetaNN (i.e., classification of host phenotypes from Metagenomic data using Neural Networks), a neural network framework which utilizes a new data augmentation technique to mitigate the effects of data over-fitting.

CONCLUSIONS: We show that MetaNN outperforms existing state-of-the-art models in terms of classification accuracy for both synthetic and real metagenomic data. These results pave the way towards developing personalized treatments for microbiome related diseases.

RevDate: 2019-08-14
CmpDate: 2019-08-14

Karabudak S, Ari O, Durmaz B, et al (2019)

Analysis of the effect of smoking on the buccal microbiome using next-generation sequencing technology.

Journal of medical microbiology, 68(8):1148-1158.

PURPOSE: This study aimed to investigate the effect of smoking on the buccal microbiome and to analyse the descriptive ability of each of the seven hypervariable regions in their 16S rRNA genes.

METHODOLOGY: Microbiome compositions of 40 buccal swab samples collected from smokers (n =20) and non-smokers (n =20) were determined using 16S rRNA sequencing. Seven different 16S rRNA hypervariable regions (V2, V3, V4, V6-7, V8 and V9) in each sample were amplified using the Ion Torrent 16S Metagenomics kit and were sequenced on the Ion S5 instrument.

RESULTS: Seven hypervariable regions in the 16S rRNA gene were successfully sequenced for all samples tested. The data obtained with the V2 region was found to be informative but the consensus data generated according to a number of operational taxonomic unit reads gathered from all seven hypervariable regions gave the most accurate result. At the phylum level, no statistically significant difference was found between smokers and non-smokers whereas relative abundances of Veillonella atypica, Streptococcus australis, Prevotella melaninogenica, Prevotella salivae and Rothia mucilaginosa showed significant increases in the smoker group (P-adj=0.05). Alpha diversity results did not show a significant difference between the two groups; however, beta diversity analysis indicated that samples of smoker and non-smoker groups had a tendency to be clustered within themselves.

CONCLUSION: The results of the current study indicate that smoking is a factor influencing buccal microbiome composition. In addition, sequencing of all seven hypervariable regions yielded more accurate results than those with any of the single variable regions.

RevDate: 2019-07-26
CmpDate: 2019-07-26

Chen CY, Tang SL, ST Chou (2019)

Taxonomy based performance metrics for evaluating taxonomic assignment methods.

BMC bioinformatics, 20(1):310 pii:10.1186/s12859-019-2896-0.

BACKGROUND: Metagenomics experiments often make inferences about microbial communities by sequencing 16S and 18S rRNA, and taxonomic assignment is a fundamental step in such studies. This paper addresses the weaknesses in two types of metrics commonly used by previous studies for measuring the performance of existing taxonomic assignment methods: Sequence count based metrics and Binary error measurement. These metrics made performance evaluation results biased, less informative and mutually incomparable.

RESULTS: We investigated weaknesses in two types of metrics and proposed new performance metrics including Average Taxonomy Distance (ATD) and ATD_by_Taxa, together with the visualized ATD plot.

CONCLUSIONS: By comparing the evaluation results from four popular taxonomic assignment methods across three test data sets, we found the new metrics more robust, informative and comparable.

RevDate: 2019-07-09
CmpDate: 2019-07-09

Wang N, Guo Y, Li G, et al (2019)

Geochemical-Compositional-Functional Changes in Arctic Soil Microbiomes Post Land Submergence Revealed by Metagenomics.

Microbes and environments, 34(2):180-190.

Lakes of meltwater in the Artic have become one of the transforming landscape changes under global warming. We herein compared microbial communities between sediments and bank soils at an arctic lake post land submergence using geochemistry, 16S rRNA amplicons, and metagenomes. The results obtained showed that each sample had approximately 2,609 OTUs on average and shared 1,716 OTUs based on the 16S rRNA gene V3-V4 region. Dominant phyla in sediments and soils included Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Nitrospirae; sediments contained a unique phylum, Euryarchaeota, with the phylum Thaumarchaeota being primarily present in bank soils. Among the top 35 genera across all sites, 17 were more abundant in sediments, while the remaining 18 were more abundant in bank soils; seven out of the top ten genera across all sites were only from sediments. A redundancy analysis separated sediment samples from soil samples based on the components of nitrite and ammonium. Metagenome results supported the role of nitrite because most of the genes for denitrification and methane metabolic genes were more abundant in sediments than in soils, while the abundance of phosphorus-utilizing genes was similar and, thus, was not a significant explanatory factor. We identified several modules from the global networks of OTUs that were closely related to some geochemical factors, such as pH and nitrite. Collectively, the present results showing consistent changes in geochemistry, microbiome compositions, and functional genes suggest an ecological mechanism across molecular and community levels that structures microbiomes post land submergence.

RevDate: 2019-07-15
CmpDate: 2019-07-15

Yachida S, Mizutani S, Shiroma H, et al (2019)

Metagenomic and metabolomic analyses reveal distinct stage-specific phenotypes of the gut microbiota in colorectal cancer.

Nature medicine, 25(6):968-976.

In most cases of sporadic colorectal cancers, tumorigenesis is a multistep process, involving genomic alterations in parallel with morphologic changes. In addition, accumulating evidence suggests that the human gut microbiome is linked to the development of colorectal cancer. Here we performed fecal metagenomic and metabolomic studies on samples from a large cohort of 616 participants who underwent colonoscopy to assess taxonomic and functional characteristics of gut microbiota and metabolites. Microbiome and metabolome shifts were apparent in cases of multiple polypoid adenomas and intramucosal carcinomas, in addition to more advanced lesions. We found two distinct patterns of microbiome elevations. First, the relative abundance of Fusobacterium nucleatum spp. was significantly (P < 0.005) elevated continuously from intramucosal carcinoma to more advanced stages. Second, Atopobium parvulum and Actinomyces odontolyticus, which co-occurred in intramucosal carcinomas, were significantly (P < 0.005) increased only in multiple polypoid adenomas and/or intramucosal carcinomas. Metabolome analyses showed that branched-chain amino acids and phenylalanine were significantly (P < 0.005) increased in intramucosal carcinomas and bile acids, including deoxycholate, were significantly (P < 0.005) elevated in multiple polypoid adenomas and/or intramucosal carcinomas. We identified metagenomic and metabolomic markers to discriminate cases of intramucosal carcinoma from the healthy controls. Our large-cohort multi-omics data indicate that shifts in the microbiome and metabolome occur from the very early stages of the development of colorectal cancer, which is of possible etiological and diagnostic importance.

RevDate: 2019-07-29
CmpDate: 2019-07-29

Zhong C, Yang Y, S Yooseph (2019)

GRASP2: fast and memory-efficient gene-centric assembly and homolog search for metagenomic sequencing data.

BMC bioinformatics, 20(Suppl 11):276 pii:10.1186/s12859-019-2818-1.

BACKGROUND: A crucial task in metagenomic analysis is to annotate the function and taxonomy of the sequencing reads generated from a microbiome sample. In general, the reads can either be assembled into contigs and searched against reference databases, or individually searched without assembly. The first approach may suffer from fragmentary and incomplete assembly, while the second is hampered by the reduced functional signal contained in the short reads. To tackle these issues, we have previously developed GRASP (Guided Reference-based Assembly of Short Peptides), which accepts a reference protein sequence as input and aims to assemble its homologs from a database containing fragmentary protein sequences. In addition to a gene-centric assembly tool, GRASP also serves as a homolog search tool when using the assembled protein sequences as templates to recruit reads. GRASP has significantly improved recall rate (60-80% vs. 30-40%) compared to other homolog search tools such as BLAST. However, GRASP is both time- and space-consuming. Subsequently, we developed GRASPx, which is 30X faster than GRASP. Here, we present a completely redesigned algorithm, GRASP2, for this computational problem.

RESULTS: GRASP2 utilizes Burrows-Wheeler Transformation (BWT) and FM-index to perform assembly graph generation, and reduces the search space by employing a fast ungapped alignment strategy as a filter. GRASP2 also explicitly generates candidate paths prior to alignment, which effectively uncouples the iterative access of the assembly graph and alignment matrix. This strategy makes the execution of the program more efficient under current computer architecture, and contributes to GRASP2's speedup. GRASP2 is 8-fold faster than GRASPx (and 250-fold faster than GRASP) and uses 8-fold less memory while maintaining the original high recall rate of GRASP. GRASP2 reaches ~ 80% recall rate compared to that of ~ 40% generated by BLAST, both at a high precision level (> 95%). With such a high performance, GRASP2 is only ~3X slower than BLASTP.

CONCLUSION: GRASP2 is a high-performance gene-centric and homolog search tool with significant speedup compared to its predecessors, which makes GRASP2 a useful tool for metagenomics data analysis, GRASP2 is implemented in C++ and is freely available from .

RevDate: 2019-08-28
CmpDate: 2019-07-15

Fettweis JM, Serrano MG, Brooks JP, et al (2019)

The vaginal microbiome and preterm birth.

Nature medicine, 25(6):1012-1021.

The incidence of preterm birth exceeds 10% worldwide. There are significant disparities in the frequency of preterm birth among populations within countries, and women of African ancestry disproportionately bear the burden of risk in the United States. In the present study, we report a community resource that includes 'omics' data from approximately 12,000 samples as part of the integrative Human Microbiome Project. Longitudinal analyses of 16S ribosomal RNA, metagenomic, metatranscriptomic and cytokine profiles from 45 preterm and 90 term birth controls identified harbingers of preterm birth in this cohort of women predominantly of African ancestry. Women who delivered preterm exhibited significantly lower vaginal levels of Lactobacillus crispatus and higher levels of BVAB1, Sneathia amnii, TM7-H1, a group of Prevotella species and nine additional taxa. The first representative genomes of BVAB1 and TM7-H1 are described. Preterm-birth-associated taxa were correlated with proinflammatory cytokines in vaginal fluid. These findings highlight new opportunities for assessment of the risk of preterm birth.

RevDate: 2019-08-20

Kallies R, Hölzer M, Brizola Toscan R, et al (2019)

Evaluation of Sequencing Library Preparation Protocols for Viral Metagenomic Analysis from Pristine Aquifer Groundwaters.

Viruses, 11(6): pii:v11060484.

Viral ecology of terrestrial habitats is yet-to be extensively explored, in particular the terrestrial subsurface. One problem in obtaining viral sequences from groundwater aquifer samples is the relatively low amount of virus particles. As a result, the amount of extracted DNA may not be sufficient for direct sequencing of such samples. Here we compared three DNA amplification methods to enrich viral DNA from three pristine limestone aquifer assemblages of the Hainich Critical Zone Exploratory to evaluate potential bias created by the different amplification methods as determined by viral metagenomics. Linker amplification shotgun libraries resulted in lowest redundancy among the sequencing reads and showed the highest diversity, while multiple displacement amplification produced the highest number of contigs with the longest average contig size, suggesting a combination of these two methods is suitable for the successful enrichment of viral DNA from pristine groundwater samples. In total, we identified 27,173, 5,886 and 32,613 viral contigs from the three samples from which 11.92 to 18.65% could be assigned to taxonomy using blast. Among these, members of the Caudovirales order were the most abundant group (52.20 to 69.12%) dominated by Myoviridae and Siphoviridae. Those, and the high number of unknown viral sequences, substantially expand the known virosphere.

RevDate: 2019-08-09
CmpDate: 2019-08-09

Qi M, Huang H, Zhang Y, et al (2019)

Novel tetrahydrofuran (THF) degradation-associated genes and cooperation patterns of a THF-degrading microbial community as revealed by metagenomic.

Chemosphere, 231:173-183.

Our understanding of the tetrahydrofuran (THF) degradation in complex environment is limited. The majority of THF degrading genes reported are group V soluble diiron monooxygenases and share greater than 95% homology with one another. In this study, we used sole-carbon-source incubation combined with high-throughput metagenomic sequencing to investigate this contaminant's degradation in environmental samples. We identified as-yet-uncultivated microbe from the genera Pseudonocardia and fungi Scedosporium sp. (Scedosporium sp. was successfully isolated) as THF degraders as containing THF degradation genes, while microbes from the genera Bordetella, Pandoraea and Rhodanobacter functioned as main cooperators by utilizing acidic intermediates and providing anti-acid mechanisms. Furthermore, a 9387-bp THF degradation cluster designated thmX from the as-yet-uncultivated Pseudonocardia (with 6 main ORFs and with 79-93% amino acid sequence identity with previously reported clusters) was discovered. We also found a THF-degrading related cytochrome P450 monooxygenase from the genus Scedosporium and predicted its cognate reductase for the first time. All the genes and clusters mentioned above were successfully amplified from samples and cloned into the suitable expression vectors. This study will provide novel insights for understanding of THF degradation mechanisms under acid stress conditions and mining new THF degradation genes.

RevDate: 2019-07-04
CmpDate: 2019-07-04

Ke S, Fang S, He M, et al (2019)

Age-based dynamic changes of phylogenetic composition and interaction networks of health pig gut microbiome feeding in a uniformed condition.

BMC veterinary research, 15(1):172 pii:10.1186/s12917-019-1918-5.

BACKGROUND: The gut microbiota impacts on a range of host biological processes, and the imbalances in its composition are associated with pathology. Though the understanding of contribution of the many factors, e.g. gender, diet and age, in the development of gut microbiota has been well established, the dynamic changes of the phylogenetic composition and the interaction networks along with the age remain unclear in pigs.

RESULTS: Here we applied 16S ribosomal RNA gene sequencing, enterotype-like clustering (Classification of the gut microbiome into distinct types) and phylogenetic co-occurrence network to explore the dynamic changes of pig gut microbiome following the ages with a successive investigation at four ages in a cohort of 953 pigs. We found that Firmicutes and Bacteroidetes are two predominant phyla throughout the experimental period. The richness of gut microbiota was significantly increased from 25 to 240 days of age. Principal coordinates analysis showed a clear difference in the gut microbial community compositions between pre-weaning piglets and the pigs at the other three age groups. The gut microbiota of pre-weaning piglets was clearly classified into two enterotypes, which were dominated by Fusobacterium and p-75-a5, respectively. However, Prevotella and Treponema were the main drivers of the enterotypes for pigs at the age of 80, 120 and 240 days. Besides the piglets, even some adult pigs switched putative enterotypes between ages. We confirmed that the topological features of phylogenetic co-occurrence networks, including scale, stability and complexity were increased along with the age. The biological significance for modules in the network of piglets were mainly associated with the utilization of simple carbohydrate and lactose, whereas the sub-networks identified at the ages of 80, 120 and 240 days may be involved in the digestion of complex dietary polysaccharide. The modules related to the metabolism of protein and amino acids could be identified in the networks at 120 and 240 days. This dynamic change of the functional capacities of gut microbiome was further supported by functional prediction analysis.

CONCLUSIONS: The present study provided meaningful biological insights into the age-based dynamic shifts of ecological community of porcine gut microbiota.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Li Y, Fu X, Ma J, et al (2019)

Altered respiratory virome and serum cytokine profile associated with recurrent respiratory tract infections in children.

Nature communications, 10(1):2288 pii:10.1038/s41467-019-10294-x.

Recurrent acute respiratory tract infections (ARTIs) affect a large population, yet the specific decisive factors are largely unknown. Here we study a population of 4407 children diagnosed with ARTI, comparing respiratory virome and serum cytokine profiles associated with multiple ARTIs and single ARTI during a six-year period. The relative abundance of Propionibacterium phages is significantly elevated in multiple ARTIs compared to single ARTI group. Serum levels of TIMP-1 and PDGF-BB are markedly increased in multiple ARTIs compared to single-ARTI and non-ARTI controls, making these two cytokines potential predictors for multiple ARTIs. The presence of Propionibacterium phages is associated with higher levels of TIMP-1 and PDGF-BB. Receiver operating characteristic (ROC) curve analyses show that the combination of TIMP-1, PDGF-BB and Propionibacterium phages could be a strong predictor for multiple ARTIs. These findings indicate that respiratory microbe homeostasis and specific cytokines are associated with the onset of multiple ARTIs over time.

RevDate: 2019-07-16
CmpDate: 2019-07-16

Liu S, Chen Q, Zou H, et al (2019)

A metagenomic analysis of the relationship between microorganisms and flavor development in Shaoxing mechanized huangjiu fermentation mashes.

International journal of food microbiology, 303:9-18.

Complex microbial metabolism is responsible for the unique flavor of Shaoxing mechanized huangjiu. However, the relationship between the microorganisms present during fermentation and the formation of specific flavor components is difficult to understand. In this study, gas chromatography-mass spectrometry and high-performance liquid chromatography were used to identify flavor components, and a metagenomic sequencing approach was used to characterize the taxonomic and functional attributes of the Shaoxing mechanized huangjiu fermentation microbiota. The metagenomic sequencing data were used to predict the relationship between microorganisms and flavor formation. The chromatographic analysis identified amino acids, alcohols, acids, phenols and esters as major flavor components, and six microbial genera (Saccharomyces, Aspergillus, Saccharopolyspora, Staphylococcus, Lactobacillus, and Lactococcus) were most closely related to the production of these flavor components. This study helps clarify the different metabolic roles of microorganisms in flavor formation during Shaoxing huangjiu fermentation.

RevDate: 2019-05-18

Sahoo K, Sahoo RK, Gaur M, et al (2019)

Cellulolytic thermophilic microorganisms in white biotechnology: a review.

Folia microbiologica pii:10.1007/s12223-019-00710-6 [Epub ahead of print].

Enzymes of microbial origin are of immense importance for organic material decomposition leading to bioremediation of organic waste, bioenergy generation, large-scale industrial bioprocesses, etc. The market demand for microbial cellulase enzyme is growing more rapidly which ultimately becomes the driving force towards research on this biocatalyst, widely used in various industrial activities. The use of novel cellulase genes obtained from various thermophiles through metagenomics and genetic engineering as well as following metabolic engineering pathways would be able to enhance the production of thermophilic cellulase at industrial scale. The present review is mainly focused on thermophilic cellulolytic bacteria, discoveries on cellulase gene, genetically modified cellulase, metabolic engineering, and their various industrial applications. A lot of lacunae are yet to overcome for thermophiles such as metagenome analysis, metabolic pathway modification study, search of heterologous hosts in gene expression system, and improved recombinant strain for better cellulase yield as well as value-added product formation.

RevDate: 2019-07-19
CmpDate: 2019-06-06

Sande CJ, Njunge JM, Mwongeli Ngoi J, et al (2019)

Airway response to respiratory syncytial virus has incidental antibacterial effects.

Nature communications, 10(1):2218 pii:10.1038/s41467-019-10222-z.

RSV infection is typically associated with secondary bacterial infection. We hypothesise that the local airway immune response to RSV has incidental antibacterial effects. Using coordinated proteomics and metagenomics analysis we simultaneously analysed the microbiota and proteomes of the upper airway and determined direct antibacterial activity in airway secretions of RSV-infected children. Here, we report that the airway abundance of Streptococcus was higher in samples collected at the time of RSV infection compared with samples collected one month later. RSV infection is associated with neutrophil influx into the airway and degranulation and is marked by overexpression of proteins with known antibacterial activity including BPI, EPX, MPO and AZU1. Airway secretions of children infected with RSV, have significantly greater antibacterial activity compared to RSV-negative controls. This RSV-associated, neutrophil-mediated antibacterial response in the airway appears to act as a regulatory mechanism that modulates bacterial growth in the airways of RSV-infected children.

RevDate: 2019-07-19
CmpDate: 2019-07-19

Lugli GA, Milani C, Duranti S, et al (2019)

Isolation of novel gut bifidobacteria using a combination of metagenomic and cultivation approaches.

Genome biology, 20(1):96 pii:10.1186/s13059-019-1711-6.

Whole metagenome shotgun (WMGS) sequencing is a method that provides insights into the genomic composition and arrangement of complex microbial consortia. Here, we report how WMGS coupled with a cultivation approach allows the isolation of novel bifidobacteria from animal fecal samples. A combination of in silico analyses based on nucleotide and protein sequences facilitate the identification of genetic material belonging to putative novel species. Consequently, the prediction of metabolic properties by in silico analyses permits the identification of specific substrates that are then employed to isolate these species through a cultivation method.

RevDate: 2019-07-18
CmpDate: 2019-07-18

Hu H, da Costa RR, Pilgaard B, et al (2019)

Fungiculture in Termites Is Associated with a Mycolytic Gut Bacterial Community.

mSphere, 4(3): pii:4/3/e00165-19.

Termites forage on a range of substrates, and it has been suggested that diet shapes the composition and function of termite gut bacterial communities. Through comparative analyses of gut metagenomes in nine termite species with distinct diets, we characterize bacterial community compositions and use peptide-based functional annotation method to determine biomass-degrading enzymes and the bacterial taxa that encode them. We find that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, while wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Interestingly, wood-feeding termite gut bacterial genes code for abundant chitinolytic enzymes, suggesting that fungal biomass within the decaying wood likely contributes to gut bacterial or termite host nutrition. Across diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community composition, with the most marked difference being the communities coding for the mycolytic capacity of the fungus-growing termite gut.IMPORTANCE Understanding functional capacities of gut microbiomes is important to improve our understanding of symbiotic associations. Here, we use peptide-based functional annotation to show that the gut microbiomes of fungus-farming termites code for a wealth of enzymes that likely target the fungal diet the termites eat. Comparisons to other termites showed that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, whereas wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Across termites with different diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community compositions.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Liu ZQ, Zhang Y, Ma XS, et al (2019)

[Nitrogen Removal Characteristics and Analysis of Microbial Community Structure in an IEM-UF Simultaneous Separation and Denitrification System].

Huan jing ke xue= Huanjing kexue, 40(3):1419-1425.

A system that combines an ion exchange membrane and ultrafiltration membrane (IEM-UF) to form a simultaneous separation and denitrification system was proposed for domestic sewage with a low carbon/nitrogen ratio. The removal of nitrogen and COD in the system was studied under a three phase operating condition. The characteristics of the microbial community in each reactor were analyzed using metagenomics. The results show that, the average rate of ammonia nitrogen enrichment in the separator reached above 116.1% when the current intensity was 0.2 A. When the system was at C/N 2.80 and operating well, the average removal rates of COD and TN reached above 90% and 50%, respectively. The maximum removal rate of TN was above 65.4%. The results of metagenomics showed a genus of phylum Nitrospirae (Nitrospira) and a genus of phylum Proteobacteria (Nitrosomonas), with the proportions of 12.23% and 2.31%, respectively. In the denitrifying reactor, Dechloromonas, Thauera, and Azospira were detected in the proportions 4.57%, 1.76%, and 1.03%, respectively. These proportions were far larger than those of other bacteria in this reactor. Meanwhile, the presence of iron autotrophic denitrifying bacteria increased the denitrification efficiency of the system.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Zhao H, Yan B, Mo S, et al (2019)

Carbohydrate metabolism genes dominant in a subtropical marine mangrove ecosystem revealed by metagenomics analysis.

Journal of microbiology (Seoul, Korea), 57(7):575-586.

Mangrove sediment microorganisms play a vital role in the energy transformation and element cycling in marine wetland ecosystems. Using metagenomics analysis strategy, we compared the taxonomic structure and gene profile of the mangrove and non-mangrove sediment samples at the subtropical estuary in Beibu Gulf, South China Sea. Proteobacteria, Bacteroidetes, and Firmicutes were the most abundant bacterial phyla. Archaeal family Methanosarcinaceae and bacterial genera Vibrio and Dehalococcoides were significantly higher in the mangrove sediments than in the nonmangrove sediments. Functional analysis showed that "Carbohydrate metabolism" was the most abundant metabolic category. The feature of carbohydrate-active enzymes (CZs) was analyzed using the Carbohydrate-Active EnZymes Database. The significant differences of CZs between mangrove and non-mangrove sediments, were attributed to the amounts of polyphenol oxidase (EC 1.10.3.-), hexosyltransferase (EC 2.4.1.-), and β-N-acetylhexosaminidase (EC, which were higher in the mangrove sediment samples. Principal component analysis indicated that the microbial community and gene profile between mangrove and non-mangrove sediments were distinct. Redundancy analysis showed that total organic carbon is a significant factor that affects the microbial community and gene distribution. The results indicated that the mangrove ecosystem with massive amounts of organic carbon may promote the richness of carbohydrate metabolism genes and enhance the degradation and utilization of carbohydrates in the mangrove sediments.

RevDate: 2019-08-08
CmpDate: 2019-08-08

Haran JP, Bhattarai SK, Foley SE, et al (2019)

Alzheimer's Disease Microbiome Is Associated with Dysregulation of the Anti-Inflammatory P-Glycoprotein Pathway.

mBio, 10(3): pii:mBio.00632-19.

The microbiota-gut-brain axis is a bidirectional communication system that is poorly understood. Alzheimer's disease (AD), the most common cause of dementia, has long been associated with bacterial infections and inflammation-causing immunosenescence. Recent studies examining the intestinal microbiota of AD patients revealed that their microbiome differs from that of subjects without dementia. In this work, we prospectively enrolled 108 nursing home elders and followed each for up to 5 months, collecting longitudinal stool samples from which we performed metagenomic sequencing and in vitro T84 intestinal epithelial cell functional assays for P-glycoprotein (P-gp) expression, a critical mediator of intestinal homeostasis. Our analysis identified clinical parameters as well as numerous microbial taxa and functional genes that act as predictors of AD dementia in comparison to elders without dementia or with other dementia types. We further demonstrate that stool samples from elders with AD can induce lower P-gp expression levels in vitro those samples from elders without dementia or with other dementia types. We also paired functional studies with machine learning approaches to identify bacterial species differentiating the microbiome of AD elders from that of elders without dementia, which in turn are accurate predictors of the loss of dysregulation of the P-gp pathway. We observed that the microbiome of AD elders shows a lower proportion and prevalence of bacteria with the potential to synthesize butyrate, as well as higher abundances of taxa that are known to cause proinflammatory states. Therefore, a potential nexus between the intestinal microbiome and AD is the modulation of intestinal homeostasis by increases in inflammatory, and decreases in anti-inflammatory, microbial metabolism.IMPORTANCE Studies of the intestinal microbiome and AD have demonstrated associations with microbiome composition at the genus level among matched cohorts. We move this body of literature forward by more deeply investigating microbiome composition via metagenomics and by comparing AD patients against those without dementia and with other dementia types. We also exploit machine learning approaches that combine both metagenomic and clinical data. Finally, our functional studies using stool samples from elders demonstrate how the c microbiome of AD elders can affect intestinal health via dysregulation of the P-glycoprotein pathway. P-glycoprotein dysregulation contributes directly to inflammatory disorders of the intestine. Since AD has been long thought to be linked to chronic bacterial infections as a possible etiology, our findings therefore fill a gap in knowledge in the field of AD research by identifying a nexus between the microbiome, loss of intestinal homeostasis, and inflammation that may underlie this neurodegenerative disorder.

RevDate: 2019-07-30
CmpDate: 2019-07-30

Hassan M, Essam T, Mira A, et al (2019)

Biomonitoring detoxification efficiency of an algal-bacterial microcosm system for treatment of coking wastewater: Harmonization between Chlorella vulgaris microalgae and wastewater microbiome.

The Science of the total environment, 677:120-130.

Nowadays, due to worldwide water shortage, water utilities are forced to re-evaluate treated wastewater. Consequently, wastewater treatment plants need to conduct biomonitoring. Coking wastewater (CWW) has toxic, mutative and carcinogenic components with threatening effect on the environment. CWW was selected as a model for complex highly toxic industrial wastewater that should be treated. CWW from Egypt was treated in a nine-liter photobioreactor using an algal-bacterial system. The photobioreactor was operated for 154 days changing different parameters (toxic load and light duration) for optimization. Optimized conditions achieved significant reduction (45%) in the operation cost. The algal-bacterial system was monitored using chemical assays (chemical oxygen demand and phenol analysis), bioassays (phytotoxicity, Artemia-toxicity, cytotoxicity, algal-bacterial ratio and settleability) and Illumina-MiSeq sequencing of 16S rRNA gene. The algal-bacterial system detoxified (in terms of phytotoxicity, cytotoxicity and Artemia-toxicity) CWW introduced as influent through all phases. A significant difference was recorded in the microbial diversity between influent and effluent samples. Four phyla dominated influent samples; Proteobacteria (77%), Firmicutes (11%), Bacteroidetes (5%) and Deferribacteres (3%) compared to only two in effluent samples; Proteobacteria (66%) and Bacteroidetes (26%). The significant relative-abundance of versatile aromatic degraders (Comamonadaceae and Pseudomonadaceae families) in influent samples conformed to the nature of CWW. Microbial community shifted and promoted the activity of catabolically versatile and xenobiotics degrading families (Chitinophagaceae and Xanthomonadaceae). Co-culture of microalgae had a positive effect on the biodegrading bacteria that was reflected by enhanced treatment efficiency, significant increase in relative abundance of bacterial genera with cyanide-decomposing potential and negative effect on waterborne pathogens.

RevDate: 2019-08-26
CmpDate: 2019-08-26

Xiao Joe JT, Chiou PP, Kuo CY, et al (2019)

The microbiota profile and transcriptome analysis of immune response during metamorphosis stages in orange spotted grouper (Epinephelus coioides).

Fish & shellfish immunology, 90:141-149.

Metamorphosis is a transformation process in larval development associated with changes in morphological and physiological features, including the immune system. The gastrointestinal tract harbors a plethora of bacteria, which might affect the digestion and absorption of nutrients, immunity, and gut-brain crosstalk in the host. In this study, we have performed metagenomic and transcriptomic analyses on the intestines of grouper at the pre-, mid- and post-metamorphosis stages. The sequencing data of 16S rRNA gene showed drastic changes in the microbial communities at different developmental stages. The transcriptomic data revealed that the leukocyte transendothelial migration and the phagosome pathways might play important roles in mediating immunity in grouper at the three developmental stages. This information will increase our understanding of the metamorphosis process in grouper larvae, and shed light on the development of antimicrobial strategy during larval development.

RevDate: 2019-07-16
CmpDate: 2019-07-16

Cabral L, Noronha MF, de Sousa STP, et al (2019)

The metagenomic landscape of xenobiotics biodegradation in mangrove sediments.

Ecotoxicology and environmental safety, 179:232-240.

Metagenomics is a powerful approach to study microorganisms present in any given environment and their potential to maintain and improve ecosystem health without the need of cultivating these microorganisms in the laboratory. In this study, we combined a cultivation-independent metagenomics approach with functional assays to identify the detoxification potential of microbial genes evaluating their potential to contribute to xenobiotics resistance in oil-impacted mangrove sediments. A metagenomic fosmid library containing 12,960 clones from highly contaminated mangrove sediment was used in this study. For assessment of metal resistance, clones were grown in culture medium with increasing concentrations of mercury. The analyses metagenomic library sequences revealed the presence of genes related to heavy metals and antibiotics resistance in the oil-impacted mangrove microbiome. The taxonomic profiling of these sequences suggests that at the genus level, Geobacter was the most abundant genus in our dataset. A functional screening assessment of the metagenomic library successfully detected 24 potential heavy metal tolerant clones, six of which were capable of growing with increased concentrations of mercury. The genetic characterization of selected clones allowed the detection of genes related to detoxification processes, such as chromate transport protein ChrA, haloacid dehalogenase-like hydrolase, lipopolysaccharide transport system, and 3-oxoacyl-[acyl-carrier-protein] reductase. Clones were capable of growing in medium containing increased concentrations of metals and antibiotics, but none manifested strong mercury removal from culture medium characteristic of mercuric reductase activity. These results suggest that resistance to xenobiotic stress varies greatly and that additional studies to elucidate the potential of metal biotransformation need to be carried out with the goal of improving bioremediation application.

RevDate: 2019-06-03
CmpDate: 2019-06-03

Escudeiro P, Pothier J, Dionisio F, et al (2019)

Antibiotic Resistance Gene Diversity and Virulence Gene Diversity Are Correlated in Human Gut and Environmental Microbiomes.

mSphere, 4(3): pii:4/3/e00135-19.

Human beings have used large amounts of antibiotics, not only in medical contexts but also, for example, as growth factors in agriculture and livestock, resulting in the contamination of the environment. Even when pathogenic bacteria are the targets of antibiotics, hundreds of nonpathogenic bacterial species are affected as well. Therefore, both pathogenic and nonpathogenic bacteria have gradually become resistant to antibiotics. We tested whether there is still cooccurrence of resistance and virulence determinants. We performed a comparative study of environmental and human gut metagenomes from different individuals and from distinct human populations across the world. We found a great diversity of antibiotic resistance determinants (AR diversity [ARd]) and virulence factors (VF diversity [VFd]) in metagenomes. Importantly there is a correlation between ARd and VFd, even after correcting for protein family richness. In the human gut, there are less ARd and VFd than in more diversified environments, and yet correlations between the ARd and VFd are stronger. They can vary from very high in Malawi, where antibiotic consumption is unattended, to nonexistent in the uncontacted Amerindian population. We conclude that there is cooccurrence of resistance and virulence determinants in human gut microbiomes, suggesting a possible coselective mechanism.IMPORTANCE Every year, thousands of tons of antibiotics are used, not only in human and animal health but also as growth promoters in livestock. Consequently, during the last 75 years, antibiotic-resistant bacterial strains have been selected in human and environmental microbial communities. This implies that, even when pathogenic bacteria are the targets of antibiotics, hundreds of nonpathogenic bacterial species are also affected. Here, we performed a comparative study of environmental and human gut microbial communities issuing from different individuals and from distinct human populations across the world. We found that antibiotic resistance and pathogenicity are correlated and speculate that, by selecting for resistant bacteria, we may be selecting for more virulent strains as a side effect of antimicrobial therapy.

RevDate: 2019-07-23
CmpDate: 2019-07-03

Zhang J, Liu YX, Zhang N, et al (2019)

NRT1.1B is associated with root microbiota composition and nitrogen use in field-grown rice.

Nature biotechnology, 37(6):676-684.

Nitrogen-use efficiency of indica varieties of rice is superior to that of japonica varieties. We apply 16S ribosomal RNA gene profiling to characterize root microbiota of 68 indica and 27 japonica varieties grown in the field. We find that indica and japonica recruit distinct root microbiota. Notably, indica-enriched bacterial taxa are more diverse, and contain more genera with nitrogen metabolism functions, than japonica-enriched taxa. Using genetic approaches, we provide evidence that NRT1.1B, a rice nitrate transporter and sensor, is associated with the recruitment of a large proportion of indica-enriched bacteria. Metagenomic sequencing reveals that the ammonification process is less abundant in the root microbiome of the nrt1.1b mutant. We isolated 1,079 pure bacterial isolates from indica and japonica roots and derived synthetic communities (SynComs). Inoculation of IR24, an indica variety, with an indica-enriched SynCom improved rice growth in organic nitrogen conditions compared with a japonica-enriched SynCom. The links between plant genotype and root microbiota membership established in this study will inform breeding strategies to improve nitrogen use in crops.

RevDate: 2019-08-20
CmpDate: 2019-08-20

Ghani MI, Ali A, Atif MJ, et al (2019)

Changes in the Soil Microbiome in Eggplant Monoculture Revealed by High-Throughput Illumina MiSeq Sequencing as Influenced by Raw Garlic Stalk Amendment.

International journal of molecular sciences, 20(9): pii:ijms20092125.

The incorporation of plant residues into soil can be considered a keystone sustainability factor in improving soil structure function. However, the effects of plant residue addition on the soil microbial communities involved in biochemical cycles and abiotic stress phenomena are poorly understood. In this study, experiments were conducted to evaluate the role of raw garlic stalk (RGS) amendment in avoiding monoculture-related production constraints by studying the changes in soil chemical properties and microbial community structures. RGS was applied in four different doses, namely the control (RGS0), 1% (RGS1), 3% (RGS2), and 5% (RGS3) per 100 g of soil. The RGS amendment significantly increased soil electrical conductivity (EC), N, P, K, and enzyme activity. The soil pH significantly decreased with RGS application. High-throughput Illumina MiSeq sequencing revealed significant alterations in bacterial community structures in response to RGS application. Among the 23 major taxa detected, Anaerolineaceae, Acidobacteria, and Cyanobacteria exhibited an increased abundance level. RGS2 increased some bacteria reported to be beneficial including Acidobacteria, Bacillus, and Planctomyces (by 42%, 64%, and 1% respectively). Furthermore, internal transcribed spacer (ITS) fungal regions revealed significant diversity among the different treatments, with taxa such as Chaetomium (56.2%), Acremonium (4.3%), Fusarium (4%), Aspergillus (3.4%), Sordariomycetes (3%), and Plectosphaerellaceae (2%) showing much abundance. Interestingly, Coprinellus (14%) was observed only in RGS-amended soil. RGS treatments effectively altered soil fungal community structures and reduced certain known pathogenic fungal genera, i.e., Fusarium and Acremonium. The results of the present study suggest that RGS amendment potentially affects the microbial community structures that probably affect the physiological and morphological attributes of eggplant under a plastic greenhouse vegetable cultivation system (PGVC) in monoculture.

RevDate: 2019-07-01
CmpDate: 2019-07-01

Tsiaoussis J, Antoniou MN, Koliarakis I, et al (2019)

Effects of single and combined toxic exposures on the gut microbiome: Current knowledge and future directions.

Toxicology letters, 312:72-97.

Human populations are chronically exposed to mixtures of toxic chemicals. Predicting the health effects of these mixtures require a large amount of information on the mode of action of their components. Xenobiotic metabolism by bacteria inhabiting the gastrointestinal tract has a major influence on human health. Our review aims to explore the literature for studies looking to characterize the different modes of action and outcomes of major chemical pollutants, and some components of cosmetics and food additives, on gut microbial communities in order to facilitate an estimation of their potential mixture effects. We identified good evidence that exposure to heavy metals, pesticides, nanoparticles, polycyclic aromatic hydrocarbons, dioxins, furans, polychlorinated biphenyls, and non-caloric artificial sweeteners affect the gut microbiome and which is associated with the development of metabolic, malignant, inflammatory, or immune diseases. Answering the question 'Who is there?' is not sufficient to define the mode of action of a toxicant in predictive modeling of mixture effects. Therefore, we recommend that new studies focus to simulate real-life exposure to diverse chemicals (toxicants, cosmetic/food additives), including as mixtures, and which combine metagenomics, metatranscriptomics and metabolomic analytical methods achieving in that way a comprehensive evaluation of effects on human health.

RevDate: 2019-05-21

Gregory AC, Zayed AA, Conceição-Neto N, et al (2019)

Marine DNA Viral Macro- and Microdiversity from Pole to Pole.

Cell, 177(5):1109-1123.e14.

Microbes drive most ecosystems and are modulated by viruses that impact their lifespan, gene flow, and metabolic outputs. However, ecosystem-level impacts of viral community diversity remain difficult to assess due to classification issues and few reference genomes. Here, we establish an ∼12-fold expanded global ocean DNA virome dataset of 195,728 viral populations, now including the Arctic Ocean, and validate that these populations form discrete genotypic clusters. Meta-community analyses revealed five ecological zones throughout the global ocean, including two distinct Arctic regions. Across the zones, local and global patterns and drivers in viral community diversity were established for both macrodiversity (inter-population diversity) and microdiversity (intra-population genetic variation). These patterns sometimes, but not always, paralleled those from macro-organisms and revealed temperate and tropical surface waters and the Arctic as biodiversity hotspots and mechanistic hypotheses to explain them. Such further understanding of ocean viruses is critical for broader inclusion in ecosystem models.

RevDate: 2019-06-07
CmpDate: 2019-06-07

Darlison J, Mogren L, Rosberg AK, et al (2019)

Leaf mineral content govern microbial community structure in the phyllosphere of spinach (Spinacia oleracea) and rocket (Diplotaxis tenuifolia).

The Science of the total environment, 675:501-512.

The plant microbiome is an important factor for plant health and productivity. While the impact of nitrogen (N) availability for plant growth and development is well established, its influence on the microbial phyllosphere community structure is unknown. We hypothesize that nitrogen impacts the growth and abundance of several microorganisms on the leaf surface. The bacterial and fungal communities of baby leaf spinach (Spinacia oleracea), and rocket (Diplotaxis tenuifolia) were investigated in a field trial for two years in a commercial setting. Nitrogen fertilizer was tested in four doses (basic nitrogen, basic + suboptimal, basic + commercial, basic + excess) with six replicates in each. Culture-independent (Illumina sequencing) and culture-dependent (viable count and identification of bacterial isolates) community studies were combined with monitoring of plant physiology and site weather conditions. This study found that alpha diversity of bacterial communities decreased in response to increasing nitrogen fertilizer dose, whereas viable counts showed no differences. Correspondingly, fungal communities of the spinach phyllosphere showed a decreasing pattern, whereas the decreasing diversity of fungal communities of rocket was not significant. Plant species and effects of annual variations on microbiome structure were observed for bacterial and fungal communities on both spinach and rocket. This study provides novel insights on the impact of nitrogen fertilizer regime on a nutrient scarce habitat, the phyllosphere.

RevDate: 2019-08-07
CmpDate: 2019-08-07

Pangallo D, Kraková L, Puškárová A, et al (2019)

Transcription activity of lactic acid bacterial proteolysis-related genes during cheese maturation.

Food microbiology, 82:416-425.

The catabolism of milk protein in cheese is one way how the microorganisms influence the sensorial characteristics of the final product. In this investigation, we paid attention to four genes [prtP (cell-envelope proteinase gene), pepX (X-prolyl dipeptidyl aminopeptidase gene), pepN (aminopeptidase gene) and bcaT (branched chain aminotransferase gene)] responsible for the production of volatile aroma-active compounds from milk proteins by lactic acid bacteria (LAB). We studied the dynamics of these genes and their corresponding LAB host, during the maturation of a raw ewes' milk-based cheese, using metagenomics and metatranscriptomics approaches. The transcriptome-oriented experiments included the analysis of total RNA (at three stages of cheese maturation) and also the construction of specific cDNA sub-libraries of the abovementioned genes. The proteolytic transcriptome analysis was supported by following the transcription activity of 16S rRNA gene and by metagenomic investigation. The combination of the described methods permitted to screen the dynamics of targeted genes throughout the cheese production. Lactococci were the major players in the LAB group, but the analysis provided also information on the role and properties of members of the genus Lactobacillus, such as Lb. rhamnosus, Lb. helveticus, Lb. pentosus, Lb. curvatus, Lb. parabuchneri, Lb. plantarum, Lb. brevis, Lb. delbrueckii, Lb. paracasei, Lb. fermentum and Lb. heilongjiangensis, proteolysis-related genes of which were active during cheese ripening.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Li J, Rettedal EA, van der Helm E, et al (2019)

Antibiotic Treatment Drives the Diversification of the Human Gut Resistome.

Genomics, proteomics & bioinformatics, 17(1):39-51.

Despite the documented antibiotic-induced disruption of the gut microbiota, the impact of antibiotic intake on strain-level dynamics, evolution of resistance genes, and factors influencing resistance dissemination potential remains poorly understood. To address this gap we analyzed public metagenomic datasets from 24 antibiotic treated subjects and controls, combined with an in-depth prospective functional study with two subjects investigating the bacterial community dynamics based on cultivation-dependent and independent methods. We observed that short-term antibiotic treatment shifted and diversified the resistome composition, increased the average copy number of antibiotic resistance genes, and altered the dominant strain genotypes in an individual-specific manner. More than 30% of the resistance genes underwent strong differentiation at the single nucleotide level during antibiotic treatment. We found that the increased potential for horizontal gene transfer, due to antibiotic administration, was ∼3-fold stronger in the differentiated resistance genes than the non-differentiated ones. This study highlights how antibiotic treatment has individualized impacts on the resistome and strain level composition, and drives the adaptive evolution of the gut microbiota.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Jiang X, Li X, Yang L, et al (2019)

How Microbes Shape Their Communities? A Microbial Community Model Based on Functional Genes.

Genomics, proteomics & bioinformatics, 17(1):91-105.

Exploring the mechanisms of maintaining microbial community structure is important to understand biofilm development or microbiota dysbiosis. In this paper, we propose a functional gene-based composition prediction (FCP) model to predict the population structure composition within a microbial community. The model predicts the community composition well in both a low-complexity community as acid mine drainage (AMD) microbiota, and a complex community as human gut microbiota. Furthermore, we define community structure shaping (CSS) genes as functional genes crucial for shaping the microbial community. We have identified CSS genes in AMD and human gut microbiota samples with FCP model and find that CSS genes change with the conditions. Compared to essential genes for microbes, CSS genes are significantly enriched in the genes involved in mobile genetic elements, cell motility, and defense mechanisms, indicating that the functions of CSS genes are focused on communication and strategies in response to the environment factors. We further find that it is the minority, rather than the majority, which contributes to maintaining community structure. Compared to health control samples, we find that some functional genes associated with metabolism of amino acids, nucleotides, and lipopolysaccharide are more likely to be CSS genes in the disease group. CSS genes may help us to understand critical cellular processes and be useful in seeking addable gene circuitries to maintain artificial self-sustainable communities. Our study suggests that functional genes are important to the assembly of microbial communities.

RevDate: 2019-04-28

Sirén K, Mak SST, Melkonian C, et al (2019)

Taxonomic and Functional Characterization of the Microbial Community During Spontaneous in vitro Fermentation of Riesling Must.

Frontiers in microbiology, 10:697.

Although there is an extensive tradition of research into the microbes that underlie the winemaking process, much remains to be learnt. We combined the high-throughput sequencing (HTS) tools of metabarcoding and metagenomics, to characterize how microbial communities of Riesling musts sampled at four different vineyards, and their subsequent spontaneously fermented derivatives, vary. We specifically explored community variation relating to three points: (i) how microbial communities vary by vineyard; (ii) how community biodiversity changes during alcoholic fermentation; and (iii) how microbial community varies between musts that successfully complete alcoholic fermentation and those that become 'stuck' in the process. Our metabarcoding data showed a general influence of microbial composition at the vineyard level. Two of the vineyards (4 and 5) had strikingly a change in the differential abundance of Metschnikowia. We therefore additionally performed shotgun metagenomic sequencing on a subset of the samples to provide preliminary insights into the potential relevance of this observation, and used the data to both investigate functional potential and reconstruct draft genomes (bins). At these two vineyards, we also observed an increase in non-Saccharomycetaceae fungal functions, and a decrease in bacterial functions during the early fermentation stage. The binning results yielded 11 coherent bins, with both vineyards sharing the yeast bins Hanseniaspora and Saccharomyces. Read recruitment and functional analysis of this data revealed that during fermentation, a high abundance of Metschnikowia might serve as a biocontrol agent against bacteria, via a putative iron depletion pathway, and this in turn could help Saccharomyces dominate the fermentation. During alcoholic fermentation, we observed a general decrease in biodiversity in both the metabarcoding and metagenomic data. Unexpected Micrococcus behavior was observed in vineyard 4 according to metagenomic analyses based on reference-based read mapping. Analysis of open reading frames using these data showed an increase of functions assigned to class Actinobacteria in the end of fermentation. Therefore, we hypothesize that bacteria might sit-and-wait until Saccharomyces activity slows down. Complementary approaches to annotation instead of relying a single database provide more coherent information true species. Lastly, our metabarcoding data enabled us to identify a relationship between stuck fermentations and Starmerella abundance. Given that robust chemical analysis indicated that although the stuck samples contained residual glucose, all fructose had been consumed, we hypothesize that this was because fructophilic Starmerella, rather than Saccharomyces, dominated these fermentations. Overall, our results showcase the different ways in which metagenomic analyses can improve our understanding of the wine alcoholic fermentation process.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Tokarz R, Tagliafierro T, Sameroff S, et al (2019)

Microbiome analysis of Ixodes scapularis ticks from New York and Connecticut.

Ticks and tick-borne diseases, 10(4):894-900.

We employed high throughput sequencing to survey the microbiomes of Ixodes scapularis collected in New York and Connecticut. We examined 197 individual I. scapularis adults and pools from 132 adults and 197 nymphs. We detected Borrelia burgdorferi sensu stricto in 56.3% of individual ticks, Anaplasma phagocytophilum in 10.6%, Borrelia miyamotoi in 5%, Babesia microti in 7.6%, and Powassan virus in 3.6%. We did not detect Borrelia mayonii, Ehrlichia muris eauclairensis, Bartonella spp. or pathogenic Babesia species other than B. microti. The most abundant bacterium (65%), and only rickettsial species identified, was the endosymbiont Rickettsia buchneri. A filarial nematode was found in 13.7% of adult ticks. Fourteen viruses were detected including South Bay virus (22%) and blacklegged tick phlebovirus 1 and 2 (73%). This study provides insight into the microbial diversity of I. scapularis in New York State and Connecticut.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Easton AV, Quiñones M, Vujkovic-Cvijin I, et al (2019)

The Impact of Anthelmintic Treatment on Human Gut Microbiota Based on Cross-Sectional and Pre- and Postdeworming Comparisons in Western Kenya.

mBio, 10(2): pii:mBio.00519-19.

Murine studies suggest that the presence of some species of intestinal helminths is associated with changes in host microbiota composition and diversity. However, studies in humans have produced varied conclusions, and the impact appears to vary widely depending on the helminth species present. To demonstrate how molecular approaches to the human gut microbiome can provide insights into the complex interplay among disparate organisms, DNA was extracted from cryopreserved stools collected from residents of 5 rural Kenyan villages prior to and 3 weeks and 3 months following albendazole (ALB) therapy. Samples were analyzed by quantitative PCR (qPCR) for the presence of 8 species of intestinal parasites and by MiSeq 16S rRNA gene sequencing. Based on pretreatment results, the presence of neither Ascaris lumbricoides nor Necator americanus infection significantly altered the overall diversity of the microbiota in comparison with age-matched controls. Following ALB therapy and clearance of soil-transmitted helminths (STH), there were significant increases in the proportion of the microbiota made up by Clostridiales (P = 0.0002; average fold change, 0.57) and reductions in the proportion made up by Enterobacteriales (P = 0.0004; average fold change, -0.58). There was a significant posttreatment decrease in Chao1 richness, even among individuals who were uninfected pretreatment, suggesting that antimicrobial effects must be considered in any posttreatment setting. Nevertheless, the helminth-associated changes in Clostridiales and Enterobacteriales suggest that clearance of STH, and of N. americanus in particular, alters the gut microbiota.IMPORTANCE The gut microbiome is an important factor in human health. It is affected by what we eat, what medicines we take, and what infections we acquire. In turn, it affects the way we absorb nutrients and whether we have excessive intestinal inflammation. Intestinal worms may have an important impact on the composition of the gut microbiome. Without a complete understanding of the impact of mass deworming programs on the microbiome, it is impossible to accurately calculate the cost-effectiveness of such public health interventions and to guard against any possible deleterious side effects. Our research examines this question in a "real-world" setting, using a longitudinal cohort, in which individuals with and without worm infections are treated with deworming medication and followed up at both three weeks and three months posttreatment. We quantify the impact of roundworms and hookworms on gut microbial composition, suggesting that the impact is small, but that treatment of hookworm infection results in significant changes. This work points to the need for follow-up studies to further examine the impact of hookworm on the gut microbiota and determine the health consequences of the observed changes.

RevDate: 2019-08-09
CmpDate: 2019-08-09

Laitinen K, K Mokkala (2019)

Overall Dietary Quality Relates to Gut Microbiota Diversity and Abundance.

International journal of molecular sciences, 20(8): pii:ijms20081835.

Disturbances in gut microbiota homeostasis may have metabolic consequences with potentially serious clinical manifestations. Diet influences the host's metabolic health in several ways, either directly or indirectly by modulating the composition and function of gut microbiota. This study investigated the extent to which dietary quality is reflected in gut microbiota diversity in overweight and obese pregnant women at risk for metabolic complications. Dietary quality was measured by a validated index of diet quality (IDQ) and microbiota composition was analyzed using 16SrRNA gene sequencing from 84 women pregnant less than 18 weeks. The alpha diversity, measured as Chao1, observed operational taxonomic units (OTUs), phylogenetic diversity, and the Shannon index were calculated. The IDQ score correlated positively with the Shannon index (rho = 0.319, p = 0.003), but not with the other indexes. The women who had the highest dietary quality (highest IDQ quartile) had higher gut microbiota diversity in all the investigated indexes, when compared to the women with the lowest dietary quality (lowest IDQ quartile; p < 0.032). Consequently, a higher dietary quality was reflected in a higher gut microbiota diversity. The presented approach may aid in devising new tools for dietary counseling aiming at holistic health, as well as in microbiome studies, to control for dietary variance.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Lorenzi AS, Chia MA, Lopes FAC, et al (2019)

Cyanobacterial biodiversity of semiarid public drinking water supply reservoirs assessed via next-generation DNA sequencing technology.

Journal of microbiology (Seoul, Korea), 57(6):450-460.

Next-generation DNA sequencing technology was applied to generate molecular data from semiarid reservoirs during well-defined seasons. Target sequences of 16S-23S rRNA ITS and cpcBA-IGS were used to reveal the taxonomic groups of cyanobacteria present in the samples, and genes coding for cyanotoxins such as microcystins (mcyE), saxitoxins (sxtA), and cylindrospermopsins (cyrJ) were investigated. The presence of saxitoxins in the environmental samples was evaluated using ELISA kit. Taxonomic analyses of high-throughput DNA sequencing data showed the dominance of the genus Microcystis in Mundaú reservoir. Furthermore, it was the most abundant genus in the dry season in Ingazeira reservoir. In the rainy season, 16S-23S rRNA ITS analysis revealed that Cylindrospermopsis raciborskii comprised 46.8% of the cyanobacterial community in Ingazeira reservoir, while the cpcBAIGS region revealed that C. raciborskii (31.8%) was the most abundant taxon followed by Sphaerospermopsis aphanizomenoides (17.3%) and Planktothrix zahidii (16.6%). Despite the presence of other potential toxin-producing genera, the detected sxtA gene belonged to C. raciborskii, while the mcyE gene belonged to Microcystis in both reservoirs. The detected mcyE gene had good correlation with MC content, while the amplification of the sxtA gene was related to the presence of STX. The cyrJ gene was not detected in these samples. Using DNA analyses, our results showed that the cyanobacterial composition of Mundaú reservoir was similar in successive dry seasons, and it varied between seasons in Ingazeira reservoir. In addition, our data suggest that some biases of analysis influenced the cyanobacterial communities seen in the NGS output of Ingazeira reservoir.

RevDate: 2019-08-27

Sung CM, Chen KF, Lin YF, et al (2019)

Predicting Clinical Outcomes of Cirrhosis Patients With Hepatic Encephalopathy From the Fecal Microbiome.

Cellular and molecular gastroenterology and hepatology, 8(2):301-318.e2.

BACKGROUND & AIMS: Gut dysbiosis plays a role in hepatic encephalopathy (HE), while its relationship at the acute episode of overt HE (AHE), the disease progression and clinical outcomes remains unclear. We aimed to identify AHE-specific microbiome and its association to patients' outcomes.

METHODS: We profiled fecal microbiome changes for a cohort of 62 patients with cirrhosis and AHE i) before treatment, ii) 2-3 days after medication and iii) 2-3 months after recovery, and three control cohorts i) healthy individuals, patients with ii) compensated or iii) decompensated cirrhosis.

RESULTS: Comparison of the microbiome shift from compensated, decompensated cirrhosis, AHE to recovery revealed the AHE-specific gut-dysbiosis. The gut microbiome diversity was decreased during AHE, further reduced after medication, and only partially reversed during the recovery. The relative abundance of Bacteroidetes phylum in the microbiome decreased, whereas that of Firmicute, Proteobacteria and Actinobacteria increased in patients during AHE compared with those with compensated cirrhosis. A total of 70 operational taxonomic units (OTUs) were significantly different between AHE and decompensated cirrhosis abundances. Of them, the abundance of Veillonella parvula increased the most during AHE via a metagenomics recovery of the genomes. Moreover, the relative abundances of three (Alistipes, Bacteroides, Phascolarctobacterium) and five OTUs (Clostridium-XI, Bacteroides, Bacteroides, Lactobacillus, Clostridium-sedis) at AHE were respectively associated with HE recurrence and overall survival during the subsequent one-year follow-up.

CONCLUSIONS: AHE-specific gut OTUs were identified that may be involved in HE development and able to predict clinical outcomes, providing new strategies for the prevention and treatment of HE recurrence in patients with cirrhosis.

RevDate: 2019-05-28
CmpDate: 2019-05-28

Dong X, Greening C, Rattray JE, et al (2019)

Metabolic potential of uncultured bacteria and archaea associated with petroleum seepage in deep-sea sediments.

Nature communications, 10(1):1816 pii:10.1038/s41467-019-09747-0.

The lack of microbial genomes and isolates from the deep seabed means that very little is known about the ecology of this vast habitat. Here, we investigate energy and carbon acquisition strategies of microbial communities from three deep seabed petroleum seeps (3 km water depth) in the Eastern Gulf of Mexico. Shotgun metagenomic analysis reveals that each sediment harbors diverse communities of chemoheterotrophs and chemolithotrophs. We recovered 82 metagenome-assembled genomes affiliated with 21 different archaeal and bacterial phyla. Multiple genomes encode enzymes for anaerobic oxidation of aliphatic and aromatic compounds, including those of candidate phyla Aerophobetes, Aminicenantes, TA06 and Bathyarchaeota. Microbial interactions are predicted to be driven by acetate and molecular hydrogen. These findings are supported by sediment geochemistry, metabolomics, and thermodynamic modelling. Overall, we infer that deep-sea sediments experiencing thermogenic hydrocarbon inputs harbor phylogenetically and functionally diverse communities potentially sustained through anaerobic hydrocarbon, acetate and hydrogen metabolism.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Cobián Güemes AG, Lim YW, Quinn RA, et al (2019)

Cystic Fibrosis Rapid Response: Translating Multi-omics Data into Clinically Relevant Information.

mBio, 10(2): pii:mBio.00431-19.

Pulmonary exacerbations are the leading cause of death in cystic fibrosis (CF) patients. To track microbial dynamics during acute exacerbations, a CF rapid response (CFRR) strategy was developed. The CFRR relies on viromics, metagenomics, metatranscriptomics, and metabolomics data to rapidly monitor active members of the viral and microbial community during acute CF exacerbations. To highlight CFRR, a case study of a CF patient is presented, in which an abrupt decline in lung function characterized a fatal exacerbation. The microbial community in the patient's lungs was closely monitored through the multi-omics strategy, which led to the identification of pathogenic shigatoxigenic Escherichia coli (STEC) expressing Shiga toxin. This case study illustrates the potential for the CFRR to deconstruct complicated disease dynamics and provide clinicians with alternative treatments to improve the outcomes of pulmonary exacerbations and expand the life spans of individuals with CF.IMPORTANCE Proper management of polymicrobial infections in patients with cystic fibrosis (CF) has extended their life span. Information about the composition and dynamics of each patient's microbial community aids in the selection of appropriate treatment of pulmonary exacerbations. We propose the cystic fibrosis rapid response (CFRR) as a fast approach to determine viral and microbial community composition and activity during CF pulmonary exacerbations. The CFRR potential is illustrated with a case study in which a cystic fibrosis fatal exacerbation was characterized by the presence of shigatoxigenic Escherichia coli The incorporation of the CFRR within the CF clinic could increase the life span and quality of life of CF patients.

RevDate: 2019-04-18

Singer GAC, Fahner NA, Barnes JG, et al (2019)

Comprehensive biodiversity analysis via ultra-deep patterned flow cell technology: a case study of eDNA metabarcoding seawater.

Scientific reports, 9(1):5991 pii:10.1038/s41598-019-42455-9.

The characterization of biodiversity is a crucial element of ecological investigations as well as environmental assessment and monitoring activities. Increasingly, amplicon-based environmental DNA metabarcoding (alternatively, marker gene metagenomics) is used for such studies given its ability to provide biodiversity data from various groups of organisms simply from analysis of bulk environmental samples such as water, soil or sediments. The Illumina MiSeq is currently the most popular tool for carrying out this work, but we set out to determine whether typical studies were reading enough DNA to detect rare organisms (i.e., those that may be of greatest interest such as endangered or invasive species) present in the environment. We collected sea water samples along two transects in Conception Bay, Newfoundland and analyzed them on the MiSeq with a sequencing depth of 100,000 reads per sample (exceeding the 60,000 per sample that is typical of similar studies). We then analyzed these same samples on Illumina's newest high-capacity platform, the NovaSeq, at a depth of 7 million reads per sample. Not surprisingly, the NovaSeq detected many more taxa than the MiSeq thanks to its much greater sequencing depth. However, contrary to our expectations this pattern was true even in depth-for-depth comparisons. In other words, the NovaSeq can detect more DNA sequence diversity within samples than the MiSeq, even at the exact same sequencing depth. Even when samples were reanalyzed on the MiSeq with a sequencing depth of 1 million reads each, the MiSeq's ability to detect new sequences plateaued while the NovaSeq continued to detect new sequence variants. These results have important biological implications. The NovaSeq found 40% more metazoan families in this environment than the MiSeq, including some of interest such as marine mammals and bony fish so the real-world implications of these findings are significant. These results are most likely associated to the advances incorporated in the NovaSeq, especially a patterned flow cell, which prevents similar sequences that are neighbours on the flow cell (common in metabarcoding studies) from being erroneously merged into single spots by the sequencing instrument. This study sets the stage for incorporating eDNA metabarcoding in comprehensive analysis of oceanic samples in a wide range of ecological and environmental investigations.

RevDate: 2019-06-18
CmpDate: 2019-06-18

Reddy B, Pandey J, SK Dubey (2019)

Assessment of environmental gene tags linked with carbohydrate metabolism and chemolithotrophy associated microbial community in River Ganga.

Gene, 704:31-41.

The microbial community mediated biogeochemical cycles play important role in global C-cycle and display a sensitive response to environmental changes. Limited information is available on microbial composition and functional diversity controlling biogeochemical cycles in the riverine environment. The Ganga River water and sediment samples were studied for environmental gene tags with reference to carbohydrate metabolism, photoheterotrophy and chemolithotrophy using high throughput shotgun metagenomic sequencing and functional annotation. The diversity of environmental gene tags specific microbial community was annotated against reference sequence database using Kaiju taxonomic classifier. The metagenomic analyses revealed that the river harbored a broad range of carbohydrate and energy metabolism genes. The in-depth investigation of metagenomic data revealed that the enzymes associated with reverse TCA cycle, Calvin-Benson cycle enzyme RuBisCO, starch and sucrose metabolism genes were highly abundant. The enzymes associated with sulfur metabolism such as EC: (sulfate to ammonium per sulfate), EC:, EC: (sulfite to H2S) were prevalent in both the class of samples. The principal component analysis of the functional profiles revealed that the water and sediment samples were clustered distinctly suggesting that both the sites had variable abundance of functional genes and associated microbiota. The taxonomic classification showed abundance of Proteobacteria, Actinobacteria and Bacteroidetes phyla. Also, the metagenomic study showed the presence of purple sulfur bacteria viz. Thiodictyon, Nitrosococcus and purple non-sulfur bacteria viz. Bradyrhozobium and Rhodobacter. The study demonstrates that the Ganga River microbiome has prevalence of functional genes involved in carbohydrate anabolism and catabolism, and CO2 fixation with great prospects in cellulose and sulfide degrading enzyme production and characterization.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Rossmassler K, Snow CD, Taggart D, et al (2019)

Advancing biomarkers for anaerobic o-xylene biodegradation via metagenomic analysis of a methanogenic consortium.

Applied microbiology and biotechnology, 103(10):4177-4192.

Quantifying functional biomarker genes and their transcripts provides critical lines of evidence for contaminant biodegradation; however, accurate quantification depends on qPCR primers that contain no, or minimal, mismatches with the target gene. Developing accurate assays has been particularly challenging for genes encoding fumarate-adding enzymes (FAE) due to the high level of genetic diversity in this gene family. In this study, metagenomics applied to a field-derived, o-xylene-degrading methanogenic consortium revealed genes encoding FAE that would not be accurately quantifiable by any previously available PCR assays. Sequencing indicated that a gene similar to the napthylmethylsuccinate synthase gene (nmsA) was most abundant, although benzylsuccinate synthase genes (bssA) also were present along with genes encoding alkylsuccinate synthase (assA). Upregulation of the nmsA-like gene was observed during o-xylene degradation. Protein homology modeling indicated that mutations in the active site, relative to a BssA that acts on toluene, increase binding site volume and accessibility, potentially to accommodate the relatively larger o-xylene. The new nmsA-like gene was also detected at substantial concentrations at field sites with a history of xylene contamination.

RevDate: 2019-08-28
CmpDate: 2019-08-28

Hua K, X Zhang (2019)

Estimating the total genome length of a metagenomic sample using k-mers.

BMC genomics, 20(Suppl 2):183 pii:10.1186/s12864-019-5467-x.

BACKGROUND: Metagenomic sequencing is a powerful technology for studying the mixture of microbes or the microbiomes on human and in the environment. One basic task of analyzing metagenomic data is to identify the component genomes in the community. This task is challenging due to the complexity of microbiome composition, limited availability of known reference genomes, and usually insufficient sequencing coverage.

RESULTS: As an initial step toward understanding the complete composition of a metagenomic sample, we studied the problem of estimating the total length of all distinct component genomes in a metagenomic sample. We showed that this problem can be solved by estimating the total number of distinct k-mers in all the metagenomic sequencing data. We proposed a method for this estimation based on the sequencing coverage distribution of observed k-mers, and introduced a k-mer redundancy index (KRI) to fill in the gap between the count of distinct k-mers and the total genome length. We showed the effectiveness of the proposed method on a set of carefully designed simulation data corresponding to multiple situations of true metagenomic data. Results on real data indicate that the uncaptured genomic information can vary dramatically across metagenomic samples, with the potential to mislead downstream analyses.

CONCLUSIONS: We proposed the question of how long the total genome length of all different species in a microbial community is and introduced a method to answer it.

RevDate: 2019-08-28
CmpDate: 2019-08-28

Abe K, Hirayama M, Ohno K, et al (2019)

ENIGMA: an enterotype-like unigram mixture model for microbial association analysis.

BMC genomics, 20(Suppl 2):191 pii:10.1186/s12864-019-5476-9.

BACKGROUND: One of the major challenges in microbial studies is detecting associations between microbial communities and a specific disease. A specialized feature of microbiome count data is that intestinal bacterial communities form clusters called as "enterotype", which are characterized by differences in specific bacterial taxa, making it difficult to analyze these data under health and disease conditions. Traditional probabilistic modeling cannot distinguish between the bacterial differences derived from enterotype and those related to a specific disease.

RESULTS: We propose a new probabilistic model, named as ENIGMA (Enterotype-like uNIGram mixture model for Microbial Association analysis), which can be used to address these problems. ENIGMA enabled simultaneous estimation of enterotype-like clusters characterized by the abundances of signature bacterial genera and the parameters of environmental effects associated with the disease.

CONCLUSION: In the simulation study, we evaluated the accuracy of parameter estimation. Furthermore, by analyzing the real-world data, we detected the bacteria related to Parkinson's disease. ENIGMA is implemented in R and is available from GitHub (

RevDate: 2019-07-23

Tan S, Liu J, Fang Y, et al (2019)

Insights into ecological role of a new deltaproteobacterial order Candidatus Acidulodesulfobacterales by metagenomics and metatranscriptomics.

The ISME journal, 13(8):2044-2057.

Several abundant but yet uncultivated bacterial groups exist in extreme iron- and sulfur-rich environments, and the physiology, biodiversity, and ecological roles of these bacteria remain a mystery. Here we retrieved four metagenome-assembled genomes (MAGs) from an artificial acid mine drainage (AMD) system, and propose they belong to a new deltaproteobacterial order, Candidatus Acidulodesulfobacterales. The distribution pattern of Ca. Acidulodesulfobacterales in AMDs across Southeast China correlated strongly with ferrous iron. Reconstructed metabolic pathways and gene expression profiles showed that they were likely facultatively anaerobic autotrophs capable of nitrogen fixation. In addition to dissimilatory sulfate reduction, encoded by dsrAB, dsrD, dsrL, and dsrEFH genes, these microorganisms might also oxidize sulfide, depending on oxygen concentration and/or oxidation reduction potential. Several genes with homology to those involved in iron metabolism were also identified, suggesting their potential role in iron cycling. In addition, the expression of abundant resistance genes revealed the mechanisms of adaptation and response to the extreme environmental stresses endured by these organisms in the AMD environment. These findings shed light on the distribution, diversity, and potential ecological role of the new order Ca. Acidulodesulfobacterales in nature.

RevDate: 2019-04-09

Brink M, Rhode C, Macey BM, et al (2019)

Metagenomic assessment of body surface bacterial communities of the sea urchin, Tripneustes gratilla.

Marine genomics pii:S1874-7787(19)30038-8 [Epub ahead of print].

Sea urchins, including Tripneustes gratilla, are susceptible to a disease known as bald sea urchin disease, which has the potential to lead to economic losses in this emerging aquaculture industry in South Africa. This disease is characterized by lesions that form on sea urchin exoskeletal surfaces. This study aimed to characterize the body surface bacterial communities associated with T. gratilla, using a 16S rDNA gene metagenomics approach, to provide insight into the bacterial agents associated with this aquaculture species, as well as with this balding disease. Bacterial samples were collected from non-lesioned healthy animals obtained from natural locations along the eastern coast of South Africa, as well as from different cultured cohorts: non-lesioned healthy-, lesioned diseased- and non-lesioned stressed animals. A total of 1,067,515 individual bacterial operational taxonomic units (OTUs) were identified, belonging to 133 family-, 123 genus- and 113 species level OTU groups. Alpha diversity analyses, based on Chao1, Shannon and Simpson indices, showed that there were no statistically significant differences (ANOVA; P > 0.05) between the respective cohorts, as all cohorts displayed a high degree of bacterial diversity. Similarly, beta diversity analyses (Non-metric multidimensional scaling) showed a large degree of overlapping OTUs across the four cohorts. Within each cohort, various OTUs commonly associated with marine environments were found, predominantly belonging to the families Vibrionaceae, Saprospiraceae, Flavobacteriaceae and Sphingomonadaceae. Differential abundance analysis (DESeq2) revealed that OTUs that are differentially abundant across cohorts were likely not responsible for this balding disease, suggesting that complex bacterial agents, rather than a specific pathogenic agent, are likely causing this disease. Furthermore, the putative metabolic functions assigned to the bacterial communities showed that heterotrophic bacteria appear to be responsible for tissue lysis of degrading animal matter. The results from this study, obtained through univariate and multivariate-based approaches, contributes to future management strategies of this emerging aquaculture species by providing insight into the bacterial communities associated with both natural and cultured environments.

RevDate: 2019-05-21
CmpDate: 2019-05-21

Martí JM (2019)

Recentrifuge: Robust comparative analysis and contamination removal for metagenomics.

PLoS computational biology, 15(4):e1006967 pii:PCOMPBIOL-D-18-01602.

Metagenomic sequencing is becoming widespread in biomedical and environmental research, and the pace is increasing even more thanks to nanopore sequencing. With a rising number of samples and data per sample, the challenge of efficiently comparing results within a specimen and between specimens arises. Reagents, laboratory, and host related contaminants complicate such analysis. Contamination is particularly critical in low microbial biomass body sites and environments, where it can comprise most of a sample if not all. Recentrifuge implements a robust method for the removal of negative-control and crossover taxa from the rest of samples. With Recentrifuge, researchers can analyze results from taxonomic classifiers using interactive charts with emphasis on the confidence level of the classifications. In addition to contamination-subtracted samples, Recentrifuge provides shared and exclusive taxa per sample, thus enabling robust contamination removal and comparative analysis in environmental and clinical metagenomics. Regarding the first area, Recentrifuge's novel approach has already demonstrated its benefits showing that microbiomes of Arctic and Antarctic solar panels display similar taxonomic profiles. In the clinical field, to confirm Recentrifuge's ability to analyze complex metagenomes, we challenged it with data coming from a metagenomic investigation of RNA in plasma that suffered from critical contamination to the point of preventing any positive conclusion. Recentrifuge provided results that yielded new biological insight into the problem, supporting the growing evidence of a blood microbiota even in healthy individuals, mostly translocated from the gut, the oral cavity, and the genitourinary tract. We also developed a synthetic dataset carefully designed to rate the robust contamination removal algorithm, which demonstrated a significant improvement in specificity while retaining a high sensitivity even in the presence of cross-contaminants. Recentrifuge's official website is The data and source code are anonymously and freely available on GitHub and PyPI. The computing code is licensed under the AGPLv3. The Recentrifuge Wiki is the most extensive and continually-updated source of documentation for Recentrifuge, covering installation, use cases, testing, and other useful topics.

RevDate: 2019-05-20
CmpDate: 2019-05-20

Cotta SR, Cadete LL, van Elsas JD, et al (2019)

Exploring bacterial functionality in mangrove sediments and its capability to overcome anthropogenic activity.

Marine pollution bulletin, 141:586-594.

Mangrove forests are highly productive yet vulnerable ecosystems that act as important carbon sinks ("blue carbon"). The objective of this work was to analyze the impact of anthropogenic activities on microbiome structure and functioning. The metagenomic analysis revealed that the taxonomic compositions were grossly similar across all mangrove microbiomes. Remarkably, these microbiomes, along the gradient of anthropogenic impact, showed fluctuations in the relative abundances of bacterial taxa predicted to be involved in sulfur cycling processes. Functions involved in sulfur metabolism, such as APS pathways (associated with sulfate reduction and sulfur oxidation processes) were prevalent across the microbiomes, being sox and dsrAB genes highly expressed on anthropogenically-impacted areas. Apparently, the oil-impacted microbiomes were more affected in taxonomic than in functional terms, as high functional redundancies were noted across them. The microbial gene diversity found was typical for a functional system, even following the previous disturbance.

RevDate: 2019-05-21
CmpDate: 2019-05-21

Fernandes C, Kankonkar H, Meena RM, et al (2019)

Metagenomic analysis of tarball-associated bacteria from Goa, India.

Marine pollution bulletin, 141:398-403.

The beaches of Goa state in India are frequently polluted with tarballs, specifically during pre-monsoon and monsoon seasons. Tarballs contain hydrocarbons, including polycyclic aromatic hydrocarbons, which pose significant environmental risks. Microbes associated with tarballs reportedly possess capabilities to degrade toxic hydrocarbons present in tarballs. In this study, bacterial diversity associated with tarballs from Vagator and Morjim beaches of north Goa was analysed based on V3-V4 regions of 16S rRNA gene sequenced using Illumina Miseq Platform. The Proteobacterial members were dominant in both Vagator (≥85.5%) and Morjim (≥94.0%) samples. Many of the identified taxa have been previously reported as hydrocarbon degraders (e.g. Halomonas, Marinobacter) or possible human pathogens (e.g. Acinetobacter, Klebsiella, Rhodococcus, Staphylococcus, Vibrio). This is the first study reported on a metagenomic analysis of bacteria associated with tarballs from Goa.

RevDate: 2019-07-29
CmpDate: 2019-07-29

Wei T, Bao JY, Yang HH, et al (2019)

Musa basjoo regulates the gut microbiota in mice by rebalancing the abundance of probiotic and pathogen.

Microbial pathogenesis, 131:205-211.

Musa basjoo is a kind of popular slimming fruit in southern China. However, even though the trophic component and physiological effect are well studied, its internal mechanism in reconstructing gut microbiota remains unclear. In this study, maturity of M. basjoo were divided into four levels. Results indicated that M. basjoo in level Ⅱ (with 35% maturity) represented the greatest increase in the growth in vitro of probiotics, Lactobacillus plantarum FMNP01 and Lactobacillus casei FMNP02. After feeding M. basjoo with the middle dose (2.67 g/kg·BW) to mice for 21 days, gut microbiota from mice feces was isolated and sequenced. Results of 16SrDNA sequencing showed that the scattered genera of gut microbiota were significantly gathered. The amounts of different pathogens were decreased, while probiotics such as genera Bacteroides and Roseburia were significantly increased (p < 0.05). Results of function prediction indicated that the reconstruction of gut microbiota may due to the change in carbohydrate transportation, biosynthesis of cell wall, cell membrane, and cell envelope. This study has drawn a basic mechanism in reconstructing gut microbiota by feeding M. basjoo and lay out a foundation for further reach on the interaction between human as diner and M. basjoo as food.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Raymond F, Boissinot M, Ouameur AA, et al (2019)

Culture-enriched human gut microbiomes reveal core and accessory resistance genes.

Microbiome, 7(1):56 pii:10.1186/s40168-019-0669-7.

BACKGROUND: Low-abundance microorganisms of the gut microbiome are often referred to as a reservoir for antibiotic resistance genes. Unfortunately, these less-abundant bacteria can be overlooked by deep shotgun sequencing. In addition, it is a challenge to associate the presence of resistance genes with their risk of acquisition by pathogens. In this study, we used liquid culture enrichment of stools to assemble the genome of lower-abundance bacteria from fecal samples. We then investigated the gene content recovered from these culture-enriched and culture-independent metagenomes in relation with their taxonomic origin, specifically antibiotic resistance genes. We finally used a pangenome approach to associate resistance genes with the core or accessory genome of Enterobacteriaceae and inferred their propensity to horizontal gene transfer.

RESULTS: Using culture-enrichment approaches with stools allowed assembly of 187 bacterial species with an assembly size greater than 1 million nucleotides. Of these, 67 were found only in culture-enriched conditions, and 22 only in culture-independent microbiomes. These assembled metagenomes allowed the evaluation of the gene content of specific subcommunities of the gut microbiome. We observed that differentially distributed metabolic enzymes were associated with specific culture conditions and, for the most part, with specific taxa. Gene content differences between microbiomes, for example, antibiotic resistance, were for the most part not associated with metabolic enzymes, but with other functions. We used a pangenome approach to determine if the resistance genes found in Enterobacteriaceae, specifically E. cloacae or E. coli, were part of the core genome or of the accessory genome of this species. In our healthy volunteer cohort, we found that E. cloacae contigs harbored resistance genes that were part of the core genome of the species, while E. coli had a large accessory resistome proximal to mobile elements.

CONCLUSION: Liquid culture of stools contributed to an improved functional and comparative genomics study of less-abundant gut bacteria, specifically those associated with antibiotic resistance. Defining whether a gene is part of the core genome of a species helped in interpreting the genomes recovered from culture-independent or culture-enriched microbiomes.

RevDate: 2019-08-13
CmpDate: 2019-08-13

Grieco MB, Lopes FAC, Oliveira LS, et al (2019)

Metagenomic Analysis of the Whole Gut Microbiota in Brazilian Termitidae Termites Cornitermes cumulans, Cyrilliotermes strictinasus, Syntermes dirus, Nasutitermes jaraguae, Nasutitermes aquilinus, Grigiotermes bequaerti, and Orthognathotermes mirim.

Current microbiology, 76(6):687-697.

Although some previous studies have described the microbial diversity of termite in Brazil, the lack of studies about this subject is still evident. In the present study, we described by whole genome sequencing, the gut microbiota of seven species of termites (Termitidae) with different feeding habits from four Brazilian locations. For the litter species, the most abundant bacterial phylum was Firmicutes, where Cornitermes cumulans and Syntermes dirus (Syntermitinae) were identified. For the humus species, the most abundant bacterial phylum was Proteobacteria where three species were studied: Cyrilliotermes strictinasus (Syntermitinae), Grigiotermes bequaerti (Apicotermitinae), and Orthognathotermes mirim (Termitinae). For the wood termites, Firmicutes and Spirochaetes were the most abundant phyla, respectively, where two species were identified: Nasutitermes aquilinus and Nasutitermes jaraguae (Nasutitermitinae). The gut microbiota of all four examined subfamilies shared a conserved functional and carbohydrate-active enzyme profile and specialized in cellulose and chitin degradation. Taken together, these results provide insight into the partnerships between termite and microbes that permit the use of refractory energy sources.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Deng Y, Xu X, Yin X, et al (2019)

Effect of stock density on the microbial community in biofloc water and Pacific white shrimp (Litopenaeus vannamei) gut microbiota.

Applied microbiology and biotechnology, 103(10):4241-4252.

Biofloc technology is an efficient approach for intensive shrimp culture. However, the extent to which this process can influence the composition of intestinal microbial community is still unknown. Here, we surveyed the shrimp intestinal bacteria as well as the floc water from three biofloc systems with different stock densities. Our study revealed a similar variation trend in phylum taxonomy level between floc bacteria and gut microbiota. Microbial community varied notably in floc water from different stock densities, while a core genus with dominating relative abundance was detected in gut samples. Extensive variation was discovered in gut microbiota, but still clustered into groups according to stock density. Our results indicated that shrimp intestinal microbiota as well as bacteria aggregated in flocs assembled into distinct communities from different stock densities, and the intestinal communities were more similar with the surrounding environment as the increase of stock density and resulting high floc biomass. The high stock density changed the core gut microbiota by reducing the relative abundance of Paracoccus and increasing that of Nocardioides, which may negatively influence shrimp performance. Therefore, this study helps us to understand further bacteria and host interactions in biofloc system.

RevDate: 2019-08-26
CmpDate: 2019-08-26

Sevigny JL, Rothenheber D, Diaz KS, et al (2019)

Marker genes as predictors of shared genomic function.

BMC genomics, 20(1):268 pii:10.1186/s12864-019-5641-1.

BACKGROUND: Although high-throughput marker gene studies provide valuable insight into the diversity and relative abundance of taxa in microbial communities, they do not provide direct measures of their functional capacity. Recently, scientists have shown a general desire to predict functional profiles of microbial communities based on phylogenetic identification inferred from marker genes, and recent tools have been developed to link the two. However, to date, no large-scale examination has quantified the correlation between the marker gene based taxonomic identity and protein coding gene conservation. Here we utilize 4872 representative prokaryotic genomes from NCBI to investigate the relationship between marker gene identity and shared protein coding gene content.

RESULTS: Even at 99-100% marker gene identity, genomes share on average less than 75% of their protein coding gene content. This occurs regardless of the marker gene(s) used: V4 region of the 16S rRNA, complete 16S rRNA, or single copy orthologs through a multi-locus sequence analysis. An important aspect related to this observation is the intra-organism variation of 16S copies from a single genome. Although the majority of 16S copies were found to have high sequence similarity (> 99%), several genomes contained copies that were highly diverged (< 97% identity).

CONCLUSIONS: This is the largest comparison between marker gene similarity and shared protein coding gene content to date. The study highlights the limitations of inferring a microbial community's functions based on marker gene phylogeny. The data presented expands upon the results of previous studies that examined one or few bacterial species and supports the hypothesis that 16S rRNA and other marker genes cannot be directly used to fully predict the functional potential of a bacterial community.

RevDate: 2019-04-04

Sessa L, Reddel S, Manno E, et al (2019)

Distinct gut microbiota profile in antiretroviral therapy-treated perinatally HIV-infected patients associated with cardiac and inflammatory biomarkers.

AIDS (London, England), 33(6):1001-1011.

OBJECTIVE: Persistent inflammation and higher risk to develop cardiovascular diseases still represent a major complication for HIV-infected patients despite effective antiretroviral therapy (ART). We investigated the correlation between the gut microbiota profile, markers of inflammation, vascular endothelial activation (VEA) and microbial translocation (MT) in perinatally HIV-infected patients (PHIV) under ART.

DESIGN: Cross-sectional study including 61 ART-treated PHIV (age range 3-30 years old) and 71 age-matched healthy controls. Blood and stool sample were collected at the same time and analyzed for gut microbiota composition and plasma biomarkers.

METHODS: Gut microbiota composition was determined by 16S rRNA targeted-metagenomics. Soluble markers of MT, inflammation and VEA were quantified by ELISA or Luminex assay. Markers of immune activation were analyzed by flow cytometry on CD4 and CD8T cells.

RESULTS: We identified two distinct gut microbiota profiles (groups A and B) among PHIV. No different clinical parameters (age, sex, ethnicity, clinical class), dietary and sexual habits were found between the groups. The group A showed a relative dominance of Akkermansia muciniphila, whereas gut microbiota of group B was characterized by a higher biodiversity. The analysis of soluble markers revealed a significantly higher level of soluble E-selectine (P = 0.0296), intercellular adhesion molecule-1 (P = 0.0028), vascular adhesion molecule-1 (P = 0.0230), IL-6 (P = 0.0247) and soluble CD14 (P = 0.0142) in group A compared with group B.

CONCLUSION: Distinctive gut microbiota profiles are differently associated with inflammation, microbial translocation and VEA. Future studies are needed to understand the role of A. muciniphila and risk to develop cardiovascular diseases in PHIV.

RevDate: 2019-08-01
CmpDate: 2019-08-01

Liu Z, Kong Y, Gao Y, et al (2019)

Revealing the interaction between intrauterine adhesion and vaginal microbiota using high‑throughput sequencing.

Molecular medicine reports, 19(5):4167-4174.

Intrauterine adhesion (IUA) is one of the most common diseases of the reproductive system. Due to the high postoperative recurrence rate of IUA, it is crucial to identify the possible causes of pathogenesis and recurrence of this disease. In the present study, a high‑throughput sequencing approach was applied to compare the vaginal microbiota between healthy women [healthy vaginal secretion (HVS) group] and patients with IUA [intrauterine adhesion patients' vaginal secretion (IAVS) group]. The results indicated that IUA had little effect on the number of vaginal bacterial species. However, at the phylum level, patients with IUA had a significantly lower percentage of Firmicutes and a higher percentage of Actinobacteria than the HVS group (P<0.05). At the genus level, ~50% of patients with IUA were found to have a marked reduction in probiotic Lactobacillus accompanied by an overgrowth of pathogenic Gardnerella and Prevotella (P<0.05), and the Principal Coordinates Analysis confirmed that 10/20 samples in the IAVS group were scattered far away from the HVS group. Therefore, it was concluded that the interaction between IUA and vaginal microbiota greatly influenced the vaginal diversity of patients with IUA. In order to increase the recovery rate and lower the recurrence rate of IUA, increasing the vaginal Lactobacillus population should be considered.

RevDate: 2019-06-19
CmpDate: 2019-05-10

Thomas AM, Manghi P, Asnicar F, et al (2019)

Metagenomic analysis of colorectal cancer datasets identifies cross-cohort microbial diagnostic signatures and a link with choline degradation.

Nature medicine, 25(4):667-678.

Several studies have investigated links between the gut microbiome and colorectal cancer (CRC), but questions remain about the replicability of biomarkers across cohorts and populations. We performed a meta-analysis of five publicly available datasets and two new cohorts and validated the findings on two additional cohorts, considering in total 969 fecal metagenomes. Unlike microbiome shifts associated with gastrointestinal syndromes, the gut microbiome in CRC showed reproducibly higher richness than controls (P < 0.01), partially due to expansions of species typically derived from the oral cavity. Meta-analysis of the microbiome functional potential identified gluconeogenesis and the putrefaction and fermentation pathways as being associated with CRC, whereas the stachyose and starch degradation pathways were associated with controls. Predictive microbiome signatures for CRC trained on multiple datasets showed consistently high accuracy in datasets not considered for model training and independent validation cohorts (average area under the curve, 0.84). Pooled analysis of raw metagenomes showed that the choline trimethylamine-lyase gene was overabundant in CRC (P = 0.001), identifying a relationship between microbiome choline metabolism and CRC. The combined analysis of heterogeneous CRC cohorts thus identified reproducible microbiome biomarkers and accurate disease-predictive models that can form the basis for clinical prognostic tests and hypothesis-driven mechanistic studies.

RevDate: 2019-06-07
CmpDate: 2019-06-07

Wei Z, Yu S, Huang Z, et al (2019)

Simultaneous removal of elemental mercury and NO by mercury induced thermophilic community in membrane biofilm reactor.

Ecotoxicology and environmental safety, 176:170-177.

Thermophilic membrane biofilm reactor (TMBR) for elemental mercury (Hg0) and NO removal in simulated flue gas was investigated at oxygen content of 6% and 60 °C. The performance, the microbial community structures, gene function and the mechanism for Hg0 and NO removal in the TMBR were evaluated. TMBR achieved effective simultaneous Hg0 and NO removal in 210 days of operation, Hg0 and NO removal efficiency were up to 88.9% and 85.3%, respectively. Mercury induced thermophilic community had been formed significantly. Comamonas, Pseudomonas, Desulfomicrobium, Burkholderia and Halomonas were thermophilic mercury resistant bacteria. Brucella, Paracoccus, Tepidiphilus, Proteobacteria, Pseudomonas and Symbiobacterium were nitrifying/denitrifying genera, and had functional genes of mercury and nitrogen metabolism, as shown by16S rDNA and metagenomic sequencing. The biofilm in TMBR was characterized by XPS, HPLC. XPS and HPLC spectra indicate the formation of a mercuric species (Hg2+) from mercury oxidation. TMBR used oxygen as electron acceptor, NO and Hg0 as electron donor in nitrification; O2, NO and NO3- could be used as electron acceptor and Hg0 as electron donor in denitrification.

RevDate: 2019-04-18

Ding GC, Bai M, Han H, et al (2019)

Microbial taxonomic, nitrogen cycling and phosphorus recycling community composition during long-term organic greenhouse farming.

FEMS microbiology ecology, 95(5):.

Understanding the interplay between the farming system and soil microbiomes could aid the design of a sustainable and efficient farming system. A comparative greenhouse experiment consisting of organic (ORG), integrated (INT) and conventional (CON) farming systems was established in northern China in 2002. The effects of 12 years of organic farming on soil microbiomes were explored by metagenomic and 16S rRNA gene amplicon sequencing analyses. Long-term ORG shifted the community composition of dominant phyla, especially Acidobacteria, increased the relative abundance of Ignavibacteria and Acidobacteria Gp6 and decreased the relative abundance of Nitrosomonas, Bacillus and Paenibacillus. Metagenomic analysis further revealed that relative abundance of ammonia oxidizing microorganisms (Bacteria and Archaea) and anaerobic ammonium oxidation bacteria decreased during ORG. Conversely, the relative abundance of bacteria-carrying periplasmic nitrate reductases (napA) was slightly higher for ORG. Long-term organic farming also caused significant alterations to the community composition of functional groups associated with ammonia oxidation, denitrification and phosphorus recycling. In summary, this study provides key insights into the composition of soil microbiomes and long-term organic farming under greenhouse conditions.

RevDate: 2019-07-18
CmpDate: 2019-07-18

Klima CL, Holman DB, Ralston BJ, et al (2019)

Lower Respiratory Tract Microbiome and Resistome of Bovine Respiratory Disease Mortalities.

Microbial ecology, 78(2):446-456.

Bovine respiratory disease (BRD) continues to be a serious health problem in beef cattle production. A multifactorial condition, BRD encompasses several types of pneumonia that are associated with multiple viral and bacterial agents. Comprehensive identification of microbes associated with BRD fatalities could enhance our understanding of the range of pathogens that contribute to the disease and identify new therapeutic targets. This study used metagenomic analysis to describe the lower respiratory tract microbiome and resistome of 15 feedlot cattle BRD and 3 non-BRD mortalities along with any affiliated integrative and conjugative elements (ICEs). Known bacterial pathogens associated with BRD, including Histophilus somni, Mannheimia haemolytica, and Mycoplasma bovis, were relatively abundant (> 5%) in most, but not all samples. Other relatively abundant genera (> 1%) included Acinetobacter, Bacillus, Bacteroides, Clostridium, Enterococcus, and Pseudomonas. Antimicrobial resistance genes (ARGs) comprised up to 0.5% of sequences and many of these genes were associated with ICEs previously described within the Pasteurellaceae family. A total of 20 putative ICEs were detected among 16 samples. These results document the wide diversity of microorganisms in the lower respiratory tract of cattle that have succumbed to BRD. The data also strongly suggest that antimicrobial-resistant Pasteurellaceae strains are prevalent in BRD cases in Alberta and that the resistance observed is associated with ICEs. The presence of ICEs harboring a wide array of ARGs holds significant consequence for the effectiveness of drug therapies for the control of BRD in beef cattle.

RevDate: 2019-08-19
CmpDate: 2019-08-19

Zeevi D, Korem T, Godneva A, et al (2019)

Structural variation in the gut microbiome associates with host health.

Nature, 568(7750):43-48.

Differences in the presence of even a few genes between otherwise identical bacterial strains may result in critical phenotypic differences. Here we systematically identify microbial genomic structural variants (SVs) and find them to be prevalent in the human gut microbiome across phyla and to replicate in different cohorts. SVs are enriched for CRISPR-associated and antibiotic-producing functions and depleted from housekeeping genes, suggesting that they have a role in microbial adaptation. We find multiple associations between SVs and host disease risk factors, many of which replicate in an independent cohort. Exploring genes that are clustered in the same SV, we uncover several possible mechanistic links between the microbiome and its host, including a region in Anaerostipes hadrus that encodes a composite inositol catabolism-butyrate biosynthesis pathway, the presence of which is associated with lower host metabolic disease risk. Overall, our results uncover a nascent layer of variability in the microbiome that is associated with microbial adaptation and host health.

RevDate: 2019-05-20
CmpDate: 2019-05-20

Thomas M, Wongkuna S, Ghimire S, et al (2019)

Gut Microbial Dynamics during Conventionalization of Germfree Chicken.

mSphere, 4(2): pii:4/2/e00035-19.

A gnotobiotic Gallus gallus (chicken) model was developed to study the dynamics of intestinal microflora from hatching to 18 days of age employing metagenomics. Intestinal samples were collected from a local population of feral chickens and administered orally to germfree 3-day-old chicks. Animals were euthanized on days 9 and 18 postinoculation, and intestinal samples were collected and subjected to metagenomic analysis. On day 18, the five most prevalent phyla were Bacteroidetes (43.03 ± 3.19%), Firmicutes (38.51 ± 2.67%), Actinobacteria (6.77 ± 0.7%), Proteobacteria (6.38 ± 0.7%), and Spirochaetes (2.71 ± 0.55%). Principal-coordinate analysis showed that the day 18 variables clustered more closely than the day 9 variables, suggesting that the microbial communities had changed temporally. The Morista-Horn index values ranged from 0.7 to 1, indicating that the communities in the inoculum and in the day 9 and day 18 samples were more similar than dissimilar. The predicted functional profiles of the microbiomes of the inoculum and the day 9 and day 18 samples were also similar (values of 0.98 to 1). These results indicate that the gnotobiotic chicks stably maintained the phylogenetic diversity and predicted metabolic functionality of the inoculum community.IMPORTANCE The domestic chicken is the cornerstone of animal agriculture worldwide, with a flock population exceeding 40 billion birds/year. It serves as an economically valuable source of protein globally. The microbiome of poultry has important effects on chicken growth, feed conversion, immune status, and pathogen resistance. The aim of our research was to develop a gnotobiotic chicken model appropriate for the study chicken gut microbiota function. Our experimental model shows that young germfree chicks are able to colonize diverse sets of gut bacteria. Therefore, besides the use of this model to study mechanisms of gut microbiota interactions in the chicken gut, it could be also used for applied aspects such as determining the safety and efficacy of new probiotic strains derived from chicken gut microbiota.

RevDate: 2019-06-21
CmpDate: 2019-06-21

Akyol Ç, Ozbayram EG, Demirel B, et al (2019)

Linking nano-ZnO contamination to microbial community profiling in sanitary landfill simulations.

Environmental science and pollution research international, 26(13):13580-13591.

Nanomaterials (NMs) commercially used for various activities mostly end up in landfills. Reduced biogas productions reported in landfill reactors create a need for more comprehensive research on these greatly-diverse microbial pools. In order to evaluate the impact of one of the most widely-used NMs, namely nano-zinc oxide (nano-ZnO), simulated bioreactor and conventional landfills were operated using real municipal solid waste (MSW) for 300 days with addition nano-ZnO. Leachate samples were taken at different phases and analyzed by 16S rRNA gene amplicon sequencing. The bacterial communities were distinctly characterized by Cloacamonaceae (phylum WWE1), Rhodocyclaceae (phylum Proteobacteria), Porphyromonadaceae (phylum Bacteroidetes), and Synergistaceae (phylum Synergistetes). The bacterial community in the bioreactors shifted at the end of the operation and was dominated by Rhodocyclaceae. There was not a major change in the bacterial community in the conventional reactors. The methanogenic archaeal diversity highly differed between the bioreactors and conventional reactors. The dominance of Methanomicrobiaceae was observed in the bioreactors during the peak methane-production period; however, their prominence shifted to WSA2 in the nano-ZnO-added bioreactor and to Methanocorpusculaceae in the control bioreactor towards the end. Methanocorpusculaceae was the most abundant family in both conventional control and nano-ZnO-containing reactors.