Gut commensal Parabacteroides goldsteinii-derived CDCA mediates FXR signalling to improve mucosal barrier function

The gut microbiome plays a crucial role in maintaining barrier integrity. However, it remains urgently needed to mining the gut microbiota that contribute to intestinal mucus barrier and to understand their biological mechanisms. In this study, the Lueyang black-boned chicken (LBC, a Chinese native breed) exhibited higher abundances of Bacteroidetes and Parabacteroides and stronger intestinal barrier function than Arbor Acres (AA, a commercial breed) broilers. Microbiota transplantation from LBC to AA broilers improved the intestinal barrier function. Bacteroides expanded the exclusive metabolic niche of Parabacteroides goldsteinii by producing small metabolites, thereby increasing P. goldsteinii abundance within the gut. P. goldsteinii was identified as the main contributor to the enhanced intestinal mucosal barrier. P. goldsteinii bio-transformed the taurochenodeoxycholic acid into chenodeoxycholic acid, promoting mucin production via farnesoid X receptor activation. Collectively, these findings highlight that the gut microbiota of LBC creates an exclusive metabolic niche for P. goldsteinii through cross-feeding, and reveal the critical role of P. goldsteinii-mediated bile acid biotransformation in enhancing intestinal mucosal barrier function.