Study on the Optimum Conditions about Submerged Fermentation for Polysaccharide of Cordyceps and Composition of Polysaccharide

This article studies the best submergered fermentation condition about polysaccharide of Cordyceps militaris. The experiment is designed at different level of culture mediums, pH, inoculation amount, fermentation time and temperature. The orthogonal design experiments show that the best conditions is: the culture medium is composed of corn powder 2%,sucrose 5%?yeast lixiviate 0.03%?NH4NO3 0.04%?KNO3 0.08%?MgSO4·7H2O 0.02%?K2HPO4 0.04%?FeSO4·7H2O 0.02%,at temperature 22℃,with pH6.0,and the best fermentation time is 5 days with a rotation speed of 120rpm. The results are as follows: dry Cordyceps militaris 546mg , the isolation yield of exopolysaccharide and intracellular polysaccharide are 114.8 mg/100 mL and 170.3 mg/100 mL culture liquid. Intracellular polysaccharide yield and expolysaccharide yield are present positive correlation with mycelium biomass and intracellular polysaccharide yield is higher than expolysaccharide yield. By silica-gel-G Chromatography we find that both exopolysaccharide and intracellular polysaccharide are primarily composed of three saccharides:Glucose, Mannose and Galactose.