Microbial communities from lean or obese are differently shaped after apple fibres supplementation

Background Obese microbial communities differ from lean ones. Previous studies have shown how dietary fiber interventions target the gut microbiome and effectively attenuate obesity-related conditions. Nevertheless, the mechanisms by which dietary fibres shape the gut microbiota are not elucidated yet. This in-vitro study investigated the differences between lean and obese microbiota and how they responded to dietary interventions using a multi-omics approach. Results By employing in vitro digestion followed by microcolonic fermentations, we exposed obese and lean microbial communities to apple as a representative complex food matrix, apple pectin as a soluble fiber, and cellulose as an insoluble fibe. Metagenomics and metabolomics data indicated that obese and lean individuals had distinct starting microbial communities and functions. After 24 hours of exposure to different feeding conditions, the diet-responsive bacteria modulated the composition and functionality of lean and obese microbial communities. In the obese, the results suggested different mechanisms among gut commensals with an opportunistic lifestyle, allowing them to maximize their energy production from substrates breakdown and produce a specific profile of gut microbial metabolites (GMMs). Conclusion At the taxonomical and functional level, our results underscore that dietary fibres shape bacterial communities differently depending on their initial microbial composition. This modulation affects the production of GMMs. Eating foods high in fiber is recognised to promotes a healthy gut microbiome. However, the same intervention can result in varying metabolic profiles depending on the microbial communities, which may affect the host differently. ### Competing Interest Statement The authors have declared no competing interest.