Development of an in vitro model of the gut microbiota enriched in mucus-adhering bacteria

Culturing the gut microbiota in in vitro models that mimic the intestinal environment is increasingly becoming a promising alternative approach to study microbial dynamics and the effect of perturba-tions on the gut communities. Since the mucus-associated microbial populations in the human intes-tine differ in composition and functions from their luminal counterpart, we aimed at reproducing in vitro the microbial consortia adhering to mucus using an already established three-dimensional model of the human gut microbiota. Electrospun gelatin structures supplemented or not with mucins were in-oculated with fecal samples and compared for their ability to support microbial adhesion and growth over time, as well as to shape the composition of the colonizing communities. Both scaffolds allowed the establishment of long-term stable biofilms with comparable total bacterial loads and biodiversity. However, mucin-coated structures harbored microbial consortia especially enriched in Akkermansia, Lactobacillus, and Faecalibacterium, being therefore able to select microorganisms commonly con-sidered mucosa-associated in vivo. These findings highlight the importance of mucins in shaping the intestinal microbial communities also in artificial gut microbiota systems. We propose our in vitro model based on mucin-coated electrospun gelatin structures as a valid device for studies evaluating the effects of exogenous factors (nutrients, probiotics, infectious agents, and drugs) on the mucus-adhering microbial communi-ties.