Microbiota-accessible fiber activates short-chain fatty acid and bile acid metabolism to improve intestinal mucus barrier in broiler chickens

ABSTRACT Dietary polysaccharides are closely associated with gut microbiota and intestinal function homeostasis. This study aimed to investigate the mechanisms by which the β-glucan, arabinoxylan, and resistant starch selectively modulate gut microbiota and microbiota-derived metabolites to protect the intestinal mucus barrier in broiler chicken. In the present study, cecal microbiota samples from 21-day-old broilers were cultured in vitro with β-glucan, arabinoxylan, or resistant starch as the sole carbon source. We found that β-glucan, arabinoxylan and resistant starch alter community structure and selectively target the enrichment of Bacteroides , Lactobacillus, Coprococcus , Butyricicoccus , Ruminococcus and Blautia , respectively. Notably, supplementing fiber-deficient diets with arabinoxylan and resistant starch, but not with β-glucan, improved the intestinal mucus barrier by cecal microbiota enrichment and increase in the concentration of microbiota-derived short-chain fatty acids (SCFAs). In addition, we illustrated through bacterial cultures in vitro that the supplementation of arabinoxylan and resistant starch resulted in a change in bacterial biotransformation of secondary bile acids. Our findings provide insight into how arabinoxylan and resistant starch may selectively target gut microbiota and mediate the production of SCFAs and bile acid biotransformation to improve intestinal mucus barrier function. IMPORTANCE The intestinal mucus barrier, located at the interface of the intestinal epithelium and the microbiota, is the first line of defense against pathogenic microorganisms and environmental antigens. Dietary polysaccharides, which act as microbiota-accessible fiber, play a key role in the regulation of intestinal microbial communities. However, the mechanism via which dietary fiber affects the intestinal mucus barrier through targeted regulation of the gut microbiota is not clear. This study provides fundamental evidence for the benefits of dietary fiber supplementation in broiler chickens through improvement in the intestinal mucus barrier by targeted regulation of the gut ecosystem. Our findings suggest that the microbiota-accessible fiber-gut microbiota-short-chain fatty acid/bile acid axis plays a key role in regulating intestinal function.