Use of the M-SHIME® in vitro dynamic gastrointestinal model to induce enhanced mucus adhesion properties in probiotics for prophylactic and therapeutic use

Probiotic oral administration has emerged as a promising strategy for preventing gut microbial dysbiosis and mitigating infections caused by pathogenic bacteria in both humans and animals. However, a major limitation to the efficacy of orally delivered probiotics lies in their ability to effectively colonize the gastrointestinal tract. Successful colonization requires that probiotics survive the harsh conditions of the gastrointestinal environment, retain functional viability, adhere to the intestinal mucus layer, and be present in adequate numbers. Enhanced mucosal adhesion is hypothesized to improve colonization efficiency, thereby augmenting the probiotic’s capacity to modulate the gut microbiota, inhibit pathogenic organisms, and ultimately benefit host health.
In this study, we aimed to engineer a Lactiplantibacillus plantarum strain with improved mucin adhesion capability, to enable exploitation of the principle of competitive exclusion, a natural strategy employed by microorganisms to outcompete others within the same ecological niche. We employed a modified Simulator of the Human Intestinal Microbial Ecosystem (SHIME®), incorporating a mucosal compartment (M-SHIME®), to simulate physiologically relevant gastrointestinal conditions. L. plantarum was subjected to prolonged exposure to low pH and pancreatic juice to promote the emergence of spontaneous mutants with enhanced mucus adhesion under adverse conditions. Selected sub-strains were further evaluated through 72-hour anaerobic batch fermentations using a simplified M-SHIME® system (without human microbiota). From this screening, eight mutant strains exhibiting increased mucin-adhesion potential were isolated.
Further characterization of these eight mutants was assessed in the presence of human fecal microbiota derived from three healthy donors. Ten short-term batch fermentation assays were performed in triplicate, with the wild-type strain serving as a control. After 72 hours of incubation, 50% of the mucin-adhered bacterial fraction was isolated and plated on MRS agar, while the remainder was subjected to metataxonomic analysis. Concurrently, daily sampling of luminal contents allowed for monitoring of microbial community dynamics and metabolite production in response to probiotic supplementation.
This study demonstrates the ability of the M-SHIME® platform and its derived models to generate and characterize probiotic strains with enhanced mucin adherence following exposure to physiologically relevant stressors. We further demonstrate the characterization of mutants of interest, and their potential impact on host microbiota and health.