Exopolysaccharides from Bacillus amyloliquefaciens DMBA-K4 ameliorate dextran sodium sulfate-induced colitis via gut microbiota modulation

Accumulating evidences have reported that polysaccharide could alleviate colitis through the maintenance of intestinal homeostasis. In this study, an exopolysaccharide (EPS-K4) from Bacillus amyloliquefaciens was obtained via anionic-exchange chromatography which was with an average molecular weight of 10,067 Da and consisted of mannose, rhamnose, glucuronic acid, and glucose with a molar ratio of 40.09:23.65:11.42:17.68. Furthermore, administration of EPS-K4 relieved symptoms in colitis mice via gut microbiota modulation. The levels of pathogenic bacteria, such as Enterococcus and Escherichia-Shigella, were significantly suppressed. In contrast, the levels of Lactobacillus and intestinal microbiota diversity were increased. EPS-K4 could stimulate mucin secretion to maintain the integrity of the gut barrier and decrease the levels of virulent substances (endotoxin, diamine oxidase, and D-lactic acid) in serum. The pro-inflammatory cytokines (TNF-alpha) in serum were reduced, conversely, anti-inflammatory cytokines (IL-10) were increased. These findings indicated the possibility of EPS-K4 as a chemotherapy candidate for the prevention of colitis.