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:Gut microbiota dysbiosis characterizes systemic metabolic alteration, yet its causality is debated. To address this issue, we transplanted antibiotic-free conventional wild-type mice with either dysbiotic (“obese”) or eubiotic (“lean”) gut microbiota and fed them either a NC or a 72%HFD. We report that, on NC, obese gut microbiota transplantation reduces hepatic gluconeogenesis with decreased hepatic PEPCK activity, compared to non-transplanted mice. Of note, this phenotype is blunted in conventional NOD2KO mice. By contrast, lean microbiota transplantation did not affect hepatic gluconeogenesis. In addition, obese microbiota transplantation changed both gut microbiota and microbiome of recipient mice. Interestingly, hepatic gluconeogenesis, PEPCK and G6Pase activity were reduced even once mice transplanted with the obese gut microbiota were fed a 72%HFD, together with reduced fed glycaemia and adiposity compared to non-transplanted mice. Notably, changes in gut microbiota and microbiome induced by the transplantation were still detectable on 72%HFD. Finally, we report that obese gut microbiota transplantation may impact on hepatic metabolism and even prevent HFD-increased hepatic gluconeogenesis. Our findings may provide a new vision of gut microbiota dysbiosis, useful for a better understanding of the aetiology of metabolic diseases. all livers are from NC-fed mice only.
Project description:The link between the gut microbiota and the human physiological state has been demonstrated in recent years. High gut microbiota diversity has been linked to many beneficial functions necessary or human health, while dysbiosis has been correlated to different pathological states. In this context, the study of the gut microbiota results of high relevance been necessary the development of different techniques capable of characterizing this complex ecosystem. Metaproteomics has been proved useful in the characterization of complex protein samples becoming a suitable tool for the study of these microbial communities. However, due to the complexity of these samples, protein extraction protocols may affect metaproteomics results. In this context, we evaluated stool sample processing (SSP) and microbial cell disruption, assessing the impact of different protocol modifications in the number of peptides and proteins identified. We compared different stool processing conditions and microbial cell disruption methods in terms of protein and peptide identifications and taxonomic profiles.
Project description:The human gut microbiota plays a vital role in host health by acting as a barrier against pathogens, boosting the immune system, and metabolizing complex carbon sources into beneficial compounds such as short-chain fatty acids (SCFAs). However, external factors like diet and xenobiotics, including food colorants, can impact this microbial community. Brilliant blue FCF (E-133), a common food dye that is not absorbed or metabolized by the body, thus, leading to significant exposure of the gut microbiota, and its effects on it are not well-documented. This study investigated the impact of brilliant blue on the simplified human gut microbiota model (SIHUMIx) over a seven-day exposure period, followed by a four-day recovery phase. Using continuous culture bioreactors along with metaproteomic and metabolomic analyses, the research uncovered substantial structural and functional changes in the microbiota. Our findings showed alterations in the species abundance such as B. thetaiotaomicron, B. longum, and C. butyricum, reductions in energy metabolism by-products, particularly lactate and butyrate, and disruptions in metabolic pathways involved in the metabolism of xenobiotics and amino acids. The results indicate that brilliant blue exposure compromises microbiota stability and functionality, highlighting the need for further research on its long-term effects and recovery mechanisms. This study underscores the importance of assessing the impacts of food additives on gut microbiota as part of comprehensive health risk evaluations.