Project description:We analyze differential gene expression of Salmonella Tm M2702 and E. coli Mt1B1 in mice colonized with two different gnotobiotic consortia
Project description:In this study, the minimal consortium Oligo-Mouse Microbiota (OMM)12 was used to study the function of Coriobacteriia under defined conditions in gnotobiotic mice. OMM12 mice with or without adding the dominant gut bacterium Eggerthella lenta were fed with diets varying in fat content or supplemented with primary bile acids. Changes in the host liver proteomes were studied using untargeted proteomics.
Project description:The large-scale application of genomic and metagenomic sequencing technologies has yielded a number of insights about the metabolic potential of symbiotic human gut microbes. Bacteria that colonize the mucosal layer that overlies the gut epithelium have access to highly-sulfated polysaccharides (i.e., mucin oligosaccharides and glycosaminoglycans), which they could potentially forage as nutrient sources. To be active, sulfatases must undergo a critical post-translational modification catalyzed in anaerobic bacteria by the AdoMet enzyme anSME (anaerobic Sulfatase-Maturating Enzyme). In the present study, we have tested the role of this pathway in the prominent gut symbiont Bacteroides thetaiotaomicron, which possesses more predicted sulfatases (28) than in the human genome and a single predicted anSME. In vitro studies revealed that deletion of its anSME (BT0238) results in loss of sulfatase activity and impaired ability to use sulfated polysaccharides as carbon sources. Co-colonization of germ-free animals with both isogenic strains, or invasion experiments involving the introduction of one then the other strain, established that anSME activity and the sulfatases that are activated via this pathway, are important fitness factors for B. thetaiotaomicron, especially when mice are fed a simple sugar diet that requires this saccharolytic bacterium to adaptively forage on host glycans as nutrients. Whole genome transcriptional profiling of wild-type and the anSME mutant in vivo revealed that loss of this enzyme alters expression of genes involved in mucin utilization and that this disrupted ability to access mucosal glycans likely underlies the observed dramatic colonization defect. Comparative genomic analysis reveals that 100% of 46 fully sequenced human gut Bacteroidetes contain homologs of BT0238 and genes encoding sulfatases, suggesting that this is an important and evolutionarily conserved feature. Three replicate samples from 4 different biological treatment groups: 1. Wild-type B. thetaiotaomicron from the cecum of gnotobiotic mice fed a simple-sugar diet; 2. chuR mutant B. thetaiotaomicron from the cecum of gnotobiotic mice fed a simple-sugar diet; 3. Wild-type B. thetaiotaomicron from the cecum of gnotobiotic mice fed a plant-rich diet; 4. chuR mutant B. thetaiotaomicron from the cecum of gnotobiotic mice fed a plant-rich diet.
Project description:We illustrate an approach for integrating preclinical gnotobiotic animal models with human studies to understand the contributions of perturbed gut microbiota development to childhood undernutrition, and to identify new microbiota-directed therapeutic concepts/leads. Combining metabolomic and proteomic analyses of serially collected plasma samples with metagenomic analyses of serially collected fecal samples, we characterized the biological state of Bangladeshi children with severe acute malnutrition (SAM) as they transitioned to moderate acute malnutrition (MAM) after standard treatment. Gnotobiotic mice were subsequently colonized with a defined consortium of bacterial strains representing different stages of microbiota development in healthy children from Bangladesh. Administering different combinations of Bangladeshi complementary food ingredients to colonized mice and germ-free controls revealed diet-dependent changes in representation and metabolism of targeted weaning-phase strains, including accompanying increases in branched-chain amino acids, plus diet- and colonization-dependent augmentation of IGF-1/mTOR signaling. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes were subsequently examined in gnotobiotic mice colonized with post-SAM MAM microbiota and in gnotobiotic piglets colonized with a defined consortium of targeted age- and growth-discriminatory bacteria. Finally, ar andomized, double-blind study revealed a lead MDCF that affected the representation of targeted bacterial taxa and increased levels of biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function.
Project description:We investigated the effect of feeding mice a Total Western Diet formulated using the 50th percentile daily intake levels for macro and micronutrients from the National Health and Nutrition Examination Survey (NHANES) with 0, 2, 5, or 10% added raw potato starch on the cecal microbiome (16S) and cecum, proximal and distal colon gene expression by RNASeq analysis.
Project description:Transcriptional profiling of Salmonella typhimurium in the ceca of germ-free and Bacteroides thetaiotaomicron-monoassociated gnotobiotic mice. Comparison with response in MM-Glucose.