Project description:The rate, timing, and mode of species dispersal is recognized as a key driver of the structure and function of communities of macroorganisms, and may be one ecological process that determines the diversity of microbiomes. Many previous studies have quantified the modes and mechanisms of bacterial motility using monocultures of a few model bacterial species. But most microbes live in multispecies microbial communities, where direct interactions between microbes may inhibit or facilitate dispersal through a number of physical (e.g., hydrodynamic) and biological (e.g., chemotaxis) mechanisms, which remain largely unexplored. Using cheese rinds as a model microbiome, we demonstrate that physical networks created by filamentous fungi can impact the extent of small-scale bacterial dispersal and can shape the composition of microbiomes. From the cheese rind of Saint Nectaire, we serendipitously observed the bacterium Serratia proteamaculans actively spreads on networks formed by the fungus Mucor. By experimentally recreating these pairwise interactions in the lab, we show that Serratia spreads on actively growing and previously established fungal networks. The extent of symbiotic dispersal is dependent on the fungal network: diffuse and fast-growing Mucor networks provide the greatest dispersal facilitation of the Serratia species, while dense and slow-growing Penicillium networks provide limited dispersal facilitation. Fungal-mediated dispersal occurs in closely related Serratia species isolated from other environments, suggesting that this bacterial-fungal interaction is widespread in nature. Both RNA-seq and transposon mutagenesis point to specific molecular mechanisms that play key roles in this bacterial-fungal interaction, including chitin utilization and flagellin biosynthesis. By manipulating the presence and type of fungal networks in multispecies communities, we provide the first evidence that fungal networks shape the composition of bacterial communities, with Mucor networks shifting experimental bacterial communities to complete dominance by motile Proteobacteria. Collectively, our work demonstrates that these strong biophysical interactions between bacterial and fungi can have community-level consequences and may be operating in many other microbiomes.
Project description:Rationale: Recent studies suggest a potential link between gut bacterial microbiota dysbiosis and PAH, but the exact role of gut microbial communities, including bacteria, archaea, and fungi, in PAH remains unclear. Objectives: To investigate the role of gut microbiota dysbiosis in idiopathic pulmonary arterial hypertension (IPAH) and to assess the therapeutic potential of fecal microbiota transplantation (FMT) in modulating PAH progression. Methods: Using shotgun metagenomics, we analyzed gut microbial communities in IPAH patients and healthy controls. FMT was performed to transfer gut microbiota from IPAH patients or MCT-PAH rats to normal rats and from healthy rats to MCT-PAH rats. Hemodynamic measurements, echocardiography, histological examination, metabolomic and RNA-seq analysis were conducted to evaluate the effects of FMT on PAH phenotypes. Measurements and Main Results: Gut microbiota analysis revealed significant alterations in the bacterial, archaeal, and fungal communities in IPAH patients compared to healthy controls. FMT from IPAH patients induced PAH phenotypes in recipient rats. Conversely, FMT from healthy rats to IPAH rats significantly ameliorated PAH symptoms, restored gut microbiota composition, and normalized serum metabolite profiles. Specific microbial species were identified with high diagnostic potential for IPAH, improving predictive performance beyond individual or combined microbial communities. Conclusions: This study establishes a causal link between gut microbiota dysbiosis and IPAH and demonstrates the therapeutic potential of FMT in reversing PAH phenotypes. The findings highlight the critical role of bacterial, archaeal, and fungal communities in PAH pathogenesis and suggest that modulation of the gut microbiome could be a promising treatment strategy for PAH.
Project description:Disrupted interactions between host and intestinal bacteria are implicated in the development of colorectal cancer (CRC). However, the functional impacts of these inter-kingdom interactions remain poorly defined. To examine this interplay, we performed mouse and microbiota RNA-sequencing on colon tissue from germ-free (GF) and gnotobiotic ApcMin/+;Il10-/- mice associated with microbes from biofilm-positive human CRC tumor (BT) and biofilm-negative healthy (BX) tissues. The bacteria in BT mice differentially expressed >2,900 genes related to bacterial secretion, virulence and biofilms, but only affected 62 host genes. Importantly, the bacterial communities from BT mice were transmissible and carcinogenic when administered to a new GF ApcMin/+;Il10-/- cohort, maintaining a set of 13 bacterial genera. Our findings suggest complex interactions within bacterial communities affecting bacterial composition and CRC development.
Project description:<p><strong>Background</strong></p><p>Antibiotic treatment has a well-established detrimental effect on the gut bacterial composition, but effects on the fungal community are less clear. Bacteria in the lumen of the gastrointestinal tract may limit fungal colonization and invasion. Antibiotic drugs targeting bacteria are therefore seen as an important risk factor for fungal infections and induced allergies. However, antibiotic effects on gut bacterial-fungal interactions, including disruption and resilience of fungal community compositions, were not investigated in humans. We analysed stool samples collected from 14 healthy human participants over three months following a 6-day antibiotic administration. We integrated data from shotgun metagenomics, metatranscriptomics, metabolomics, and fungal ITS2 sequencing. </p><p><strong>Results</strong></p><p>While the bacterial community recovered mostly over three months post treatment, the fungal community was shifted from mutualism at baseline to competition. Half of the bacterial-fungal interactions present before drug intervention had disappeared three months later. During treatment, fungal abundances were associated with the expression of bacterial genes with functions for cell growth and repair. By extending the metagenomic species approach, we revealed bacterial strains inhibiting the opportunistic fungal pathogen Candida albicans. We demonstrate in vitro how C. albicans pathogenicity and host cell damage might be controlled naturally in the human gut by bacterial metabolites such as propionate or 5-dodecenoate.</p><p><strong>Conclusions</strong></p><p>We demonstrate that antibacterial drugs have long-term influence on the human gut mycobiome. While bacterial communities recovered mostly 30-days post antibacterial treatment, the fungal community was shifted from mutualism towards competition.</p><p><br></p><p><strong>Linked data:</strong></p><p>Metagenomics has been submitted to NCBI SRA repository as projects PRJNA573821, PRJNA573905 and PRJNA579284.</p>
2020-09-28 | MTBLS1846 | MetaboLights
Project description:Wheat root-associated bacterial communities Raw sequence reads
Project description:Background: While the luminal microbiome composition in the human cervicovaginal tract has been defined, the presence and impact of tissue-adherent ectocervical microbiota remain incompletely understood. Studies of luminal and tissue-associated bacteria in the gastrointestinal tract suggest that they may have distinct roles in health and disease. Here, we performed a multi-omics characterization of paired luminal and tissue samples collected from a clinically well-characterized cohort of Kenyan women. Results: We identified a tissue-adherent bacterial microbiome, with a higher alpha diversity than the luminal microbiome, in which dominant genera overall included Gardnerella and Lactobacillus, followed by Prevotella, Atopobium, and Sneathia. About half of the L. iners dominated luminal samples had a corresponding Gardnerella dominated tissue microbiome. Broadly, the tissue-adherent microbiome was associated with fewer differentially expressed host genes than the luminal microbiome. Gene set enrichment analysis revealed that L. crispatus-dominated tissue-adherent communities were associated with protein translation and antimicrobial activity, whereas a highly diverse microbiome was associated with epithelial remodeling and pro-inflammatory pathways. Communities dominated by L. iners and Gardnerella were associated with low host transcriptional activity. Tissue-adherent microbiomes dominated by Lactobacillus and Gardnerella correlated with host protein profiles associated with epithelial barrier stability, and with a more pro-inflammatory profile for the Gardnerella-dominated microbiome group. Tissue samples with a highly diverse composition had a protein profile representing cell proliferation and pro-inflammatory activity. Conclusion: We identified ectocervical tissue-adherent bacterial communities in all study participants. These communities were distinct from cervicovaginal luminal microbiota in a significant proportion of individuals. This difference could possibly explain that L. iners dominant luminal communities have a high probability of transitioning to high diverse bacterial communities including high abundance of Gardnerella. By performing integrative multi-omics analyses we further revealed that bacterial communities at both sites correlated with distinct host gene expression and protein levels. The tissue-adherent bacterial community is similar to vaginal biofilms that significantly impact women’s reproductive and sexual health.
Project description:Disrupted interactions between host and intestinal bacteria are implicated in the development of colorectal cancer (CRC). However, the functional impacts of these inter-kingdom interactions remain poorly defined. To examine this interplay, we performed small RNA sequencing on the stool of from germ-free (GF) and gnotobiotic ApcMin/+;Il10-/- mice associated with microbes from biofilm-positive human CRC tumor (BT) and biofilm-negative healthy (BX) tissues. revealed a group of significant differentially expressed miRNAs specific to BT compared to BX associated ApcMin/+;Il10-/- mice and several miRNAs that correlated with bacterial genera abundances. Our findings suggest complex interactions within bacterial communities affecting host-derived miRNA and CRC development.
Project description:Anthropogenic activities have dramatically increased the inputs of reactive nitrogen (N) into terrestrial ecosystems, with potentially important effects on the soil microbial community and consequently soil C and N dynamics. Our analysis of microbial communities in soils subjected to 14 years of 7 g N m-2 year-1 Ca(NO3)2 amendment in a Californian grassland showed that the taxonomic composition of bacterial communities, examined by 16S rRNA gene amplicon sequencing, was significantly altered by nitrate amendment, supporting the hypothesis that N amendment- induced increased nutrient availability, yielded more fast-growing bacterial taxa while reduced slow-growing bacterial taxa. Nitrate amendment significantly increased genes associated with labile C degradation (e.g. amyA and xylA) but had no effect or decreased the relative abundances of genes associated with degradation of more recalcitrant C (e.g. mannanase and chitinase), as shown by data from GeoChip targeting a wide variety of functional genes. The abundances of most N cycling genes remained unchanged or decreased except for increases in both the nifH gene (associated with N fixation), and the amoA gene (associated with nitrification) concurrent with increases of ammonia-oxidizing bacteria. Based on those observations, we propose a conceptual model to illustrate how changes of functional microbial communities may correspond to soil C and N accumulation.
Project description:Development of cereal crops with high nitrogen-use efficiency (NUE) is a priority for worldwide agriculture. In addition to conventional plant breeding and genetic engineering, the use of the plant microbiome offers another approach to improve crop NUE. To gain insight into the bacterial communities associated with sorghum lines that differ in NUE, a field experiment was designed comparing 24 diverse sorghum lines under sufficient and deficient nitrogen (N). Amplicon sequencing and untargeted gas chromatography-mass spectrometry (GC-MS) were used to characterize the bacterial communities and the root metabolome associated with sorghum genotypes varying in sensitivity to low N. We demonstrated that N stress and sorghum type (energy, sweet, and grain sorghum) significantly impacted the root-associated bacterial communities and root metabolite composition of sorghum. We found a positive correlation between sorghum NUE and bacterial richness and diversity in the rhizosphere. The greater alpha diversity in high NUE lines was associated with the decreased abundance of a dominant bacterial taxa, Pseudomonas. Multiple strong correlations were detected between root metabolites and rhizosphere bacterial communities in response to low-N stress. This indicates that the shift in the sorghum microbiome due to low-N is associated with the root metabolites of the host plant. Taken together, our findings suggest that host genetic regulation of root metabolites plays a role in defining the root-associated microbiome of sorghum genotypes differing in NUE and tolerance to low-N stress.