Studies on submerged fermentation of Pleurotus tuber-regium (Fr.) Singer—Part 1: physical and chemical factors affecting the rate of mycelial growth and bioconversion efficiency

Submerged fermentation of the mycelium of Pleurotus tuber-regium was investigated by studying the physical parameters including the amount of inoculum and duration of fermentation as well as different chemical factors including the carbon and nitrogen sources. The fermentation conditions was set at an orbital shaking of 200±10 rpm at 30±1 °C with a basal medium containing 30 g fructose, 2 g peptone, 2 g yeast extract, 1 g KH2PO4, 0.6 g MgSO4.7H2O per 1 l of distilled water. The amount of mycelial inoculum was set at 10 ml/l of medium. Growth of mycelium using glucose and fructose had a relatively shorter lag phase than that of maize starch with maximum growth on different periods of fermentation. Nitrogen utilization of yeast extract was better than that of peptone when monosaccharide was used as the sole carbon source. Maximum bioconversion efficiency found was about 40%, which was much higher than those reported previously for P. tuber-regium. In the scale-up fermentation, basal medium with fructose gave higher mycelial yield than that of glucose.