Application of a Two Stage Temperature and Aeration Control Strategy for Enhanced Diosgenin Production in an Improved Solid-State Fermentation Reactor

A two stage temperature and aeration control strategy was proposed for the production of diosgenin from Dioscorea zingiberensis (DZW) with mixed culture of Trichoderma reesei and Aspergillus fumigatus. The effect of temperature on fungal growth and enzyme production was investigated. The optimum growth temperature for T. reesei and A. fumigatus was 30°C and 40°C, respectively. The influence of temperature on enzyme transformation was also studied. High temperature (55°C or 60°C) was more suitable than low temperature (30°C or 40°C). A different temperature control strategy experiment was carried out in a flask, first. 73.8±0.51gmol/g of diosgenin was obtained from DZW by setting the temperature in the first stage of 30°C for 2 days, in the second stage of 40°C for 2 days, and in the third stage of 55°C for 2 days. Scaled up experiment was carried out in a new tray bioreactor. The temperature was set at 30°C for 2 days, and increasing to 40°C for next 4 days. The aeration speed was decreased from 200 to 100 mL/min at the 5th and 6th days. Diosgenin concentration of 72.9±1.62 gmol/g was obtained.