Production of antioxidative exopolysaccharides of Cordyceps militaris with Vernonia amygdalina leaves in substrate

Abstract

Cordyceps militaris exopolysaccharides (EPS) have many pharmacological activities such as boosting immunity and antifatigue. To obtain EPS efficiently, we added moderate Vernonia amygdalina leaf powder as inducer to the fermentation medium to promote the production of Cordyceps militaris EPS and studied the infrared absorption spectrum and antioxidant activities of the EPS after optimization. The optimum liquid fermentation conditions were as follows: addition of Vernonia amygdalina leaf powder of 8 g/L, fermentation duration of 9 d, initial pH of 6.5, inoculation quantity of 5.0 mL. Under such a condition, the yield of Cordyceps militaris EPS reached (5.24±0.28) mg/mL, increased by 205.20% compared to the control group without adding Vernonia amygdalina leaf powder. Results of infrared analysis and antioxidant activity showed that the Vernonia amygdalina leaves had little effect on the structure and activities of Cordyceps militaris EPS. The results of this research suggest that Vernonia amygdalina leaf can enhance the production of Cordyceps militaris EPS effectively, and provides a novel method for efficient production of EPS in Cordyceps militaris.