Interindividual Diversity of Human Gut Mucin-Degrading Microbial Consortia

Mucin is a glycoprotein secreted throughout the mammalian gastrointestinal tract that can support endogenous microorganisms in the absence of complex polysaccharides. While diverse mucin degrading bacteria have been identified, the individual host microbial community differences capable of metabolizing this complex polymer are not well described. To determine whether individuals have taxonomically distinct but functionally similar mucin-degrading communities, we used a ten-day in vitro sequential batch culture fermentation from three human donors with mucin as the sole carbon source. For each donor, 16S rRNA gene amplicon sequencing was used to characterize microbial community succession, and the short-chain fatty acid profile was determined from the final community. Although two of the final communities had genus-level taxonomic differences signified by the presence of Desulfovibrio and Akkermansia, other members, such as Bacteroides, were shared between all three final communities. Metabolic output differences were most notable for one of the donors communities, with significantly less production of acetate and propionate than the other two communities. These findings reinforce the concept of a taxonomically distinct and, at broad levels, a functionally redundant gut microbiome. Furthermore, the mechanisms and efficiencies of mucin degradation across individuals are important for understanding how this community-level process impacts human health.