Effect of coix seed on exopolysaccharide production of Cordyceps militaris in liquid culture

Abstract

The low yield of C. militaris exopolysaccharide limits its industrial application. To obtain the exopolysaccharides of C. militaris efficiently, a proper amount of coix seed powder as inducer was added to the fermentation medium to promote the production of exopolysaccharides. And the infrared absorption spectrum and chemical antioxidant activity of exopolysaccharides were detected. The results showed that the optimum conditions of liquid fermentation were: 6 g/L coix seed powder, 114 h, pH 7.0 and 6% inoculation. Under these conditions, the exopolysaccharides yield of C. militaris had risen to 7.96 ± 0.18 g/L, which was about 240.17% higher than that of the control group without coix seed (2.34 ± 0.14 g/L). On the contrary, the infrared analysis and antioxidant activity study indicated that coix seed had little impact on the structure and activity of exopolysaccharides produced by C. militaris. Therefore, the conclusion is that adding coix seed powder can effectively improve the yield of exopolysaccharides of C. militaris in the experiment, and will provide a new and efficient prospect for the industrial production of exopolysaccharides.