Project description:Gut microbiome research is rapidly moving towards the functional characterization of the microbiota by means of shotgun meta-omics. Here, we selected a cohort of healthy subjects from an indigenous and monitored Sardinian population to analyze their gut microbiota using both shotgun metagenomics and shotgun metaproteomics. We found a considerable divergence between genetic potential and functional activity of the human healthy gut microbiota, in spite of a quite comparable taxonomic structure revealed by the two approaches. Investigation of inter-individual variability of taxonomic features revealed Bacteroides and Akkermansia as remarkably conserved and variable in abundance within the population, respectively. Firmicutes-driven butyrogenesis (mainly due to Faecalibacterium spp.) was shown to be the functional activity with the higher expression rate and the lower inter-individual variability in the study cohort, highlighting the key importance of the biosynthesis of this microbial by-product for the gut homeostasis. The taxon-specific contribution to functional activities and metabolic tasks was also examined, giving insights into the peculiar role of several gut microbiota members in carbohydrate metabolism (including polysaccharide degradation, glycan transport, glycolysis and short-chain fatty acid production). In conclusion, our results provide useful indications regarding the main functions actively exerted by the gut microbiota members of a healthy human cohort, and support metaproteomics as a valuable approach to investigate the functional role of the gut microbiota in health and disease.
Project description:Bifidobacteria dominate the composition of the neonatal gut microbiota in the first number of weeks following birth. A number of species in particular are found with a significantly higher frequency in the microbiome of breastfed infants, owing to their ability to rely on Human Milk Oligosacchraides (HMOs) as their sole carbohydrate substrate; namely B. bifidum, B. longum spp. infantis and B. breve. Bifidobacterium kashiwanohense is a species that has been isolated previously only from the faeces of infants, but extremely infrequently at that. Relatively little is currently known about the species itself, let alone the metabolic pathways that allow it to successfully establish a population in the infant gut. We have isolated a novel strain of B. kashiwanohense from the faeces of a breastfed infant on the basis of its ability to utilise the HMO component fucosyllactose as its sole carbohydrate source. In this study, we read and annotate the full genome sequence of this novel strain, and use the data obtained to direct our further experimental analysis of fucosyllactose metabolism in B. kashiwanohense. Using transcriptomic and growth analysis results, we identify the genes responsible for B. kashiwanohense to utilise fucosyllactose, and employ a combination of cloning, in vitro hydrolysis assays, and further, recombinant transcriptomic and growth assays to elucidate the pathway for fucosyllactose metabolism in B. kashiwanohense, as well as revealing insight into fucosyllactose and fucose metabolism in Bifidobacteria as whole.
Project description:D-galactose orally intake ameliorate DNCB-induced atopic dermatitis by modulating microbiota composition and quorum sensing. The increased abundance of bacteroidetes and decreased abundance of firmicutes was confirmed. By D-galactose treatment, Bacteroides population was increased and prevotella, ruminococcus was decreased which is related to atopic dermatitis.