| In order to improve biomass and the production of extracellular polysaccharide from Paecilomyces cicadae,liquid fermentation was adopted, and the fermentation conditions of P. cicadae were optimized. Under the conditions of shaker flask fermentation, orthogonal experiment was designed based on single factor to determine the best combination of each factor. The optimum fermentation medium: sucrose 8%, beef extract 0.75%, yeast extract 0.125%, MgSO4·7H2O 0.3%, KH2PO4 0.2%, bran 0.5% was obtained after the optimization. Under these conditions, the highest yield of extracellular polysaccharide was 5.96 g/L, and the biomass was at 42 g/L, doubled than before the optimization. Afterwards, the fermentation tank was used for the expansion culture of P. cicadae, and the initial sugar concentration was optimized, and the effect of fed batch fermentation on the fermentation process was analyzed. The most suitable initial sugar concentration of fermenter culture was 5%, the highest biomass at the moment was 38 g/L and the highest extracellular polysaccharide content was 5.5 g/L under the condition. When adopting fed batch fermentation, the highest polysaccharide yield was 5.89 g/L, the highest biomass was 40 g/L, and the effect was better than batch fermentation. |
