Identification of exopolysaccharide produced by Bacillus amyloliquefaciens PFY02 and its potential biological activity and hypoglycemic function

• A novel exopolysaccharide (EPS) was obtained from Bacillus amyloliquefaciens PFY02. • The EPS was a neutral heteropolysaccharide. • The EPS has α -1,2-Man, β -1-GlcA, β -1-Gal, α -1,4-Man, and β -1-Glc glycosidic bond. • The EPS has antioxidant properties, thermal stability, and hypoglycemic function. • The EPS could increase the secretion of cholecystokinin and glucagon-like peptide-1. In this study, a novel exopolysaccharide (EPS) with antioxidant and hypoglycemic function was obtained from Bacillus amyloliquefaciens PFY02, a strain separated from strawberry juice with a high EPS production capacity (15.32 ± 0.16 g/L). After extraction and purification, structure and biological activities of the EPS were investigated. The results revealed that the EPS is a neutral heteropolysaccharide composed of mannose, glucuronide, glucose, and galactose with molar ratios in 16.91: 1.24: 6.66: 1.00. The molecular weight of EPS was 3.13 KDa, and it contained α -1,2-Man, β -1-GlcA, β -1-Gal, α -1,4-Man, and β -1-Glc glycosidic bonds. Furthermore, EPS has excellent antioxidant properties, thermal stability, water solubility, water holding capacity, emulsification as well as hypoglycemic function. Furthermore, cellular assays have confirmed that the EPS can markedly enhance the secretion of cholecystokinin and glucagon-like peptide-1 by the small intestinal endocrine cells STC-1, thereby indirectly increasing the secretion of peptide YY. Peptide YY can subsequently promote the release of insulin in pancreatic β cells RIN-m5f and decrease the release of tumor necrosis factor- alpha in Raw264.7 cells. Consequently, it suppressed inflammation, mitigated insulin resistance, and ultimately reduced blood glucose levels. Therefore, PFY02 EPS is a natural source of antioxidant and hypoglycemic functional compounds and can be applied in glycemic regulating.