B vitamin sharing promotes stability of gut microbial communities

We report the stability of gut microbiota using humanized gnotobiotic mice and in vitro anaerobic fecal culture in the context of extreme variations of dietary B vitamin supply as revealed by phylotype-to-phenotype prediction from 16S rRNA profiling and metabolomic measurements. The observed nearly unaltered relative abundance of auxotrophic species in gut communities in the face of diet or media lacking B vitamins or containing them in great excess (~30-fold above normal) points to a strong contribution of metabolic cooperation (B vitamin exchange and sharing) to the stability of gut bacterial populations.