Evaluation of microbial community reproducibility, stability and composition in a human distal gut chemostat model

In vitro gut models provide several advantages over in vivo models for the study of the human gut microbiota. However, because communities developed in these models are inevitably simplified simulations of the in vivo environment, it is necessary to broadly define the differences between in vitro consortia and the communities from which they are derived. In this study we characterized microbial community development in a twin-vessel single-stage chemostat model of the human distal gut ecosystem using both gel (Denaturing Gradient Gel Electrophoresis) and phylogenetic microarray (Human Intestinal Tract Chip) based techniques. Five different sets of twin-vessels were inoculated with feces from three different healthy adult donors and allowed to reach steady state compositions. We found that twin-vessel single-stage chemostats could develop and maintain stable, diverse, and reproducible communities that reach steady state compositions in all five runs by at most 36 days post-inoculation. As noted in other in vitro studies, steady state communities were enriched in Bacteroidetes but not Clostridium cluster XIVa, Bacilli or other Firmicutes relative to the fecal inocula. Communities developed within this model had higher within-run reproducibility than between-run repeatability when using consecutive fecal donations. Both fecal inocula and steady state chemostat communities seeded with feces from different donors had distinct compositions. We conclude that twin-vessel single-stage chemostat models represent a valid simulation of the human distal gut environment and can support complex, representative microbial communities ideal for experimental manipulation.