Project description:Cholera is a deadly diarrheal disease that affects millions of people globally. Although V. cholerae, the causative agent of the disease, has been extensively studied in isolation, it was relatively recently that scientists started investigating its interactions with the gut microbiota. Our group and others previously showed that microbiota-derived metabolites significantly influence V. cholerae behavior. By investigating how an organic extract of human feces affects V. cholerae gene expression, we recently showed that gut metabolites strongly suppress swimming motility, a virulence factor important for host colonization. Interestingly, extracts of pure cultures of a single gut commensal, Enterocloster citroniae, recapitulated this inhibitory effect. Here, we present a comprehensive examination of the effect of small molecules produced by E. citroniae and related species on V. cholerae behavior. We show that E. citroniae small molecules inhibit motility by various V. cholerae strains. We also show that several phylogenetically related species produce this activity, although the magnitude of the effect varies between strains. Using biofilm formation assays in static and shear flow conditions, we show that V. cholerae strongly induces biofilm formation in response to E. citroniae metabolites. Transcriptome and reporter analyses show that several genes involved in the synthesis of an extracellular polysaccharide are induced by growth in the presence of E. citroniae metabolites. Lastly, we show that V. cholerae interactions with host epithelial cells are also modulated by compounds produced by this commensal. These findings advance our understanding of microbiome-pathogen interactions and how commensal bacteria influence V. cholerae virulence through the production of small molecules. In the future, this knowledge may be used to design novel microbiome-based therapeutic approaches to combat cholera and other infections.
Project description:Ruminiclostridium thermocellum DSM 1313 strain adhE*(EA) expression was studied along with ∆hydG and ∆hydG∆ech mutants strains deposited under GSE54082. All strains have been described in a study entitled Elimination of hydrogenase post-translational modification blocks H2 production and increases ethanol yield in Clostridium thermocellum. Biswas, et .al. Biotechnology for Biofuels 2015 8:20 Ruminiclostridium (Clostridium) thermocellum is a leading candidate organism for implementing a consolidated bioprocessing (CBP) strategy for biofuel production due to its native ability to rapidly consume cellulose and its existing ethanol production pathway. C. thermocellum converts cellulose and cellobiose to lactate, formate, acetate, H2, ethanol, amino acids, and other products. Elimination of the pathways leading to products such as H2 could redirect carbon flux towards ethanol production. Rather than delete each hydrogenase individually, we targeted a hydrogenase maturase gene (hydG), which is involved in converting the three [FeFe] hydrogenase apoenzymes into holoenzymes by assembling the active site. This functionally inactivated all three Fe-Fe hydrogenases simultaneously, as they were unable to make active enzymes. In the ∆hydG mutant, the [NiFe] hydrogenase-encoding ech was also deleted to obtain a mutant that functionally lacks all hydrogenase. The ethanol yield increased nearly 2-fold in ∆hydG∆ech compared to wild type, and H2 production was below the detection limit. Interestingly, ∆hydG and ∆hydG∆ech exhibited improved growth in the presence of acetate in the medium. Transcriptomic and proteomic analysis reveal that genes related to sulfate transport and metabolism were up-regulated in the presence of added acetate in ∆hydG, resulting in altered sulfur metabolism. Further genomic analysis of this strain revealed a mutation in the bi-functional alcohol/aldehyde dehydrogenase adhE gene, resulting in a strain with both NADH- and NADPH-dependent alcohol dehydrogenase activities, whereas the wild type strain can only utilize NADH. This is the exact same adhE mutation found in ethanol-tolerant C. thermocellum strain E50C, but ∆hydG∆ech is not more ethanol tolerant than the wild type. Targeting protein post-translational modification is a promising new approach to target multiple enzymes simultaneously for metabolic engineering. This GEO study pertains to expression profiles generated for C. thermocellum DSM 1313 strain adhE*(EA)
Project description:Investigation of whole genome gene expression level changes in Lactococcus lactis KCTC 3769T,L. raffinolactis DSM 20443T, L. plantarum DSM 20686T, L. fujiensis JSM 16395T, L. garvieae KCTC 3772T, L. piscium DSM 6634T and L. chungangensis CAU 28T . This proves that transcriptional profiling can facilitate in elucidating the genetic distance between closely related strains.
Project description:Urolithins are a class of bioactive metabolites derived from the metabolism of dietary ellagitannins by the human gut microbiota. In the gut, urolithins are dehydroxylated regioselectively based on microbiota composition and activity. A single 9-hydroxy urolithin dehydroxylase (ucd) operon in gut resident Enterocloster species has been described to date; however, most enzymes in the urolithin metabolic pathway remain uncharacterized. Here, we investigate urolithin cross-feeding between members of the gut microbiota and discover a novel urolithin dehydroxylase in a subset of Enterocloster species. We show that urolithin intermediates, released by gut resident Gordonibacter species during ellagic acid metabolism, are dehydroxylated at both the 9- and 10-positions by E. asparagiformis, E. citroniae, and E. pacaense, but not E. bolteae. Using untargeted proteomics, we uncover a 10-hydroxy urolithin dehydroxylase operon, termed uxd, responsible for these species-specific differences in urolithin metabolism. By inducing uxd expression with diverse urolithins, we show that 9-hydroxy urolithins are required for uxd transcription and 10-position dehydroxylation. Collectively, this study reveals some of the genes, proteins, and substrate features underlying differences in urolithin metabolism by the human gut microbiota.