Comparison of culture methods on exopolysaccharide production in the submerged culture of Cordyceps militaris and process optimization

Aims: To improve exopolysaccharides (EPS) production of Cordyceps militaris (C. militaris), effects of different culture method on mycelial biomass and EPS production in the submerged culture of C. militaris were investigated. Methods and Results: A new two-stage fermentation process for EPS production of C. militaris was designed in this work. Central composite design (CCD) was utilized to optimize the two-stage fermentation process. The results showed that the two-stage fermentation process for EPS production was superior to other culture method (conventional static culture and shake culture). CCD revealed that the optimum values of the test variables for EPS production were shaken for 140 h followed by 130-h static culture. The maximum EPS production reached 3 center dot 2 g l-1 under optimized two-stage culture and was about 2 center dot 3-fold and 1 center dot 6-fold in comparison with those of original static culture and shake culture. Conclusions: It was indicated that a new two-stage culture method obtained in this work possessed a high potential for the industrial production for EPS of C. militaris. Significance and Impact of the Study: The fundamental information obtained in this work is complementary to those of previous investigations on the submerged culture of C. militaris for the production of bioactive metabolites.