Mucus-associated microbiota consortia: Insights from the advanced TIM-2muc model

The mucus layer lining the epithelium of the colon contains a microbiome that is distinct from the luminal microbiome; this is referred to as the mucus-associated microbiome (MAM). Recently, research on the MAM has gained momentum due to its significant role in immune and metabolic health. However, the study of the MAM is limited by conventional experimental techniques, as sampling this microbiome often requires invasive procedures, making in vivo research challenging. Additionally, obtaining samples from the MAM can compromise the lumen, complicating simultaneous studies of both the MAM and the lumen. To address these limitations, we present the TIM-2muc, an advanced version of the colonic in vitro model TIM-2, which includes a mucus compartment comprising both colonic mucus beads - Gut3Beads and an electrospun sheet coated with Gut3Gel. To validate whether the integrated mucus compartment behaves like the in vivo MAM, we examined the bacterial composition, alpha and beta diversity, and the MAMs composition compared to the lumen compartment of both the TIM-2muc and the conventional TIM-2 model. Our findings suggest that the MAM in the TIM-2muc model closely resembles its in vivo counterpart, thereby enhancing the physiological relevance of the luminal microbiome. TIM-2muc, an advanced TIM-2 model, presents a novel, precise, standardized, and non-invasive method for studying the MAM and LM simultaneously.