Structural and functional characterization of a porcine intestinal microbial ecosystem developed in vitro

The mammalian digestive tract harbors a vast microbial community that has the potential to modulate numerous health-related processes. Multicompartment dynamic gut models have been developed to study microbial communities in a controlled environment. To verify the assumption that the experimental results produced in vitro in a mechanical device would be highly similar to those obtained from an in vivo study, in this study fecal samples from four pigs were inoculated in a simulator of the porcine intestinal microbial ecosystem (SPIME) and cultured until reaching steady state. The composition and structure of the resultant microbial communities, and the metabolites produced were compared with those harvested from the intestine of the same pigs. Taxonomic abundance identification based on shallow shotgun metagenomic sequencing revealed only 12.1% of species or 15% of metagenome-assembled genomes (MAGs) being shared across the colon compartments of the source pigs and the SPIME. Despite these overwhelming compositional shifts, higher functional conservation was indicated as measured by functional richness, MAG-level traits, CAZymes, and untargeted metabolomics. Environmental selection and bacterial functional redundancy were considered the two key elements in microbial compositional shifts and functional preservation.