Intestinal bacteria are largely present in the intestinal lumen, yet a fraction of the microorganisms in the gastrointestinal tract can also selectively adhere to the mucus layer that covers the gut wall. These bacteria are supposed to have a key role in human health as they live in very close contact with the host. Indeed, they play an important role as a ‘barrier’ against pathogens, by instructing mucosal immune responses and occupying a niche at the expense of potentially harmful colonizers. The evaluation of changes in bacterial adhesion due to, for instance, a prebiotic treatment or the specific adhesion capacity of probiotic strains is therefore a crucial step to study host-microbiota interactions and resulting health effects.
To evaluate whether a pre- or probiotic has the capacity to enhance the adhesion of health-promoting bacteria to the gut wall, ProDigest and UGent developed an easy-to-use assay to evaluate bacterial attachment to the intestinal mucus layer. This assay includes the investigation of adhesion profiles of the intestinal microbial community from specific colonic regions from the SHIME. In this assay, samples collected at different time points are combined with the model and different bacterial groups within the attached community are quantified (Van den Abbeele et al., 2009 - Appl Microbiol Biotechnol).
A further innovation to study bacterial colonization of the gut mucus layer is represented by the M-SHIME (Mucus-SHIME). In this new model, a mucosal compartment is integrated in the colonic regions of the SHIME, allowing the microbiota to adhere to the gut mucus layer under representative conditions. The mucosal environment consists of mucin-covered microcosms for a total surface area = 800 m²/m³. The M-SHIME has been validated by analysing the adhesion of species which are known to occupy this niche in vivo (i.e. different Lactobacillus spp.).