Optimization of nutritional factors for exopolysaccharide production by submerged cultivation of the medicinal mushroom Oudemansiella radicata

Effects of nutritional factors on exopolysaccharide production by submerged cultivation of the medicinal mushroom Oudemansiella radicata were investigated in shake flasks. Sucrose and peptone were optimal carbon and nitrogen sources for cell growth and exopolysaccharide production. The exopolysaccharide production was increased with an increase in initial sucrose concentration within the range of 10-40 g l(-1) and initial peptone concentration within the range of 1-3 g l(-1). To enhance further exopolysaccharide production, the effect of carbon/nitrogen ratios was studied using central composite design (CCD) and response surface analysis. The maximum exopolysaccharide production of 2.67 +/- 0.15 g l(-1) was achieved in medium with optimized carbon and nitrogen sources, i.e. 39.3 g sucrose l(-1) and 3.16 g peptone l(-1) in the same cultivation conditions. The information obtained is helpful for the hyperproduction of exopolysaccharide by submerged cultivation of O. radicata on a large scale.