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:Quantitative metaproteomics is a relatively new research field by applying proteomics technique to study microbial proteins of microbiome, and holds the great potential to truly quantify the functional proteins actually expressed by microbes in the biological environment such as gastrointestinal tract. The significant association between arsenic exposure and gut microbiome perturbations has been reported; however, metaproteomics has not yet been applied to study arsenic induced proteome changes of microbiome. Most importantly, to our knowledge, isobaric-labeling based large-scale metaproteomics has not been reported using the advanced database search approaches such as MetaPro-IQ and matched metagenome database search strategies to provide high quantification accuracy and less missing quantification values. In the present study, a new experimental workflow coupled with isobaric labeling and MetaPro-IQ was demonstrated for metaproteomics study of arsenic induced gut microbiome perturbations. The advantages of this workflow were also discussed. For all 18 fecal samples analyzed, 7,611 protein groups were quantified without any missing values. The consistent results of expression profiles were observed between 16S rRNA gene sequencing and metaproteomics. This isobaric labeling based workflow demonstrated the significant improvement of quantitative metaproteomics for gut microbiome study.