Fig. 3
From: Metabolic network of the gut microbiota in inflammatory bowel disease
Direct and indirect metabolic interaction between commensals, pathobionts, and pathogens. Commensal Bacteroides spp. provide succinate and host-mucus derived sialic acids and fucose for the expansion of pathogenic bacteria, including EHEC, C. difficile, S. Typhimurium, and commensal E. coli (Direct metabolic network). Mucolytic bacteria, such as A. muciniphila, degrade intestinal mucus, promoting the encroachment of AIEC to the intestinal epithelium. In the epithelial niche, AIEC liberates host-derived L-serine for expansion under L-serine deficient conditions (Indirect metabolic network)