Metabolites of sea cucumber sulfated polysaccharides fermented by Parabacteroides distasonis and their effects on cross-feeding.

Sea cucumber sulfated polysaccharide (SCSPsj) is one of the dietary components which effectively modulates gut microbiota; however, the underlying mechanism remains unclear. In the present study, the interaction between SCSPsj and its utilizer (Parabacteroides distasonis) was investigated. Further study was carried out to explore the cross-feeding between intestinal Bacteroidales mediated by SCSPsj. The results revealed that SCSPsj can be fermented by P. distasonis to produce various microbial metabolites, including organic acids and derivatives, lipids and lipid-like molecules, organoheterocyclic compounds. SCSPsj can regulate the succinate pathway and acetyl-CoA pathway to influence the production of propanoic acid and acetic acid, respectively. Moreover, the SCSPsj-fermented supernatants of P. distasonis can only promote the growth of B. stercoris, B. vulgatus and P. johnsonii among 8 intestinal Bacteroidales strains through cross-feeding. The effect of cross-feeding was related to spatial distances and bacterial species. Moreover, the cross-feeding was correlated with compounds belonging to organic acids and derivatives, lipids and lipid-like molecules. These findings could provide new insights into the interaction between SCSPsj and gut microbiota.