Fermentation characteristics and hypoglycemic activity of an exopolysaccharide produced by submerged culture of Stropharia rugosoannulata #2

We have investigated the mycelial growth and extracellular polysaccharide (EPS) production of Stropharia rugosoannulata #2 under optimal culture conditions in a 5-L stirred-tank fermenter. Maximum biomass growth (16.35 g/L) was achieved after 5 days of cultivation, whereas EPS reached its maximum level (10.83 g/L) after 8 days. The morphological parameters (i.e., mean diameter, circularity, roughness, compactness) of the fungal pellets and broth viscosity were also characterized. The compactness of the pellets was determined to be significantly and positively correlated with EPS content. The hypoglycemic effect of the polysaccharide, investigated in streptozotocin-induced diabetic rats, included decreases in the plasma concentrations of glucose (37 %), total cholesterol (26 %), and triacylglycerol (24 %) and decreased aspartate aminotransferase activity (20 %). The results indicate the potential of this polysaccharide to prevent hyperglycemia in diabetic patients.