The Response of Mucosal Colonic Microbiota to Probiotic and Dietary Intervention In Vitro

Recently, the role of mucosal intestinal microbiota in human health has received increasing attention. Nevertheless, data on the response of this microbiota to various interventions remain limited. Here, we have employed the Mucosal Simulator of Human Gastrointestinal Microbial Ecosystem (M-SHIME^®) and luminal SHIME^® (L-SHIME^®) to examine mucosal microbiota responses to interventions that are known to impact the intestinal microbial community in humans and study relationships between the responses of mucosal and luminal microbiota. Specifically, we evaluated the effects of varying macronutrient levels over a 28-day standard, balanced dietary intervention and a parallel 14-day administration of <i>Lacticaseibacillus rhamnosus</i> GG. Observed shifts in mucosal microbiota in response to interventions differed significantly from those observed in luminal microbiota (<i>p</i> < 0.05). In particular, we found that the mucosal microbiota compared to luminal microbiota was more stable and that the abundance of several genera (i.e., <i>Subdoligranulum</i>, <i>Parabacteroides</i> and <i>Fusobacterium</i>) in the M-SHIME^® correlated positively with the intake of dietary macronutrients, especially protein, which was in line with results reported in previous human studies. This study demonstrates the reliability of advanced in vitro models in capturing diet-induced dynamics of the human mucosal microbiota, a compartment that remains understudied despite its critical role in intestinal immune regulation.