Studies on Optimization Conditions of Liquid Culture of Cordyceps pruinosa

Liquid culture conditions of Cordyceps pruinosa Petch were investigated through orthogonal test in shake flaskculture. The contents and constituents of the optimal liquid culture medium were sucrose 2.5%, potato starch 2%, soybean0.5%, beef extract 0.5%, yeast extract 0.1%, K2HPO4 0.1%,KCl 0.02%,MgSO4·7H2O 0.05% and so on. The suitableconditions included initial pH 5.0～7.0, inoculation size 5%(V/V), medium capacity 100ml in 250ml flask, and 15 glass beadsas dispersants, cultured at 28℃ on rotary shaker at 150r/min for 7 days. The maximum mycelial production indicated 31.86g/Lin shake flask culture. And in 10th day, its intracellular product reached the maximum yield of 3.13g/L. During shake flask cultureand bioreactor submerged batch culture,the kinetics of growth period of the fungus were analysed with pH, residual sugarconcentration, amino-nitrogen concentration, mycelial dry weight, intracellular product and so on. Then, the variations ofbiochemical parameters were similar under different culture conditions. However, the culture time of bioreactor submerged batchculture was less than shake flask culture. The maxmium mycelial dry weight 29.97g/L for 48h and the maximum intracellularproduct yield 4.95g/L for 54h was obtained. Liquid submerged batch culture was carried out in a autocontrol bioreactor andculture was conducted under the following conditions: temperature, 28℃; medium capacity, 65%(V/V); aeration size,(12±3)L/min; agitation speed, 350r/min; jar-press, 1.1MPa; inoculation size, 10%; defoamer, 0.2%; initial pH, 6.5 with mediumcomponents (edible sucrose 3%, sucrose molasses 2%, peanut 0.5%, soybean 0.5%, beef extract 0.5%, yeast extract 0.1%,K2HPO4 0.1%, KCl 0.02%, MgSO4·7H2O 0.05%.). The results of this study suggested that the liquid culture conditions ofC. pruinosa have come up to the mid-test level of industrial fermentation of fungal mycelia.