Optimization of Xylanase Production by Trichoderma orientalis Using Corn Cobs and Wheat Bran via Statistical Strategy

Abstract

In order to obtain the best conditions for xylanase production, statistical experimental designs were applied for improvement of xylanase yield by Trichoderma orientalis EU7-22 using corn cobs and wheat bran as raw materials. Plackett–Burman design was applied to evaluate the effects of eight variables (concentration of peptone, tween-80, CaCl2, MgSO4, FeSO4, as well as initial pH, fermentation temperature, fermentation time). The key factors influencing on xylanase production were identified as the fermentation time, concentration of MgSO4, and fermentation temperature. And then the path of steepest ascent was carried out to approach the optimal region of the three significant factors. These variables were subsequently further investigated by Box–Behnken design of response surface methodology. The optimum conditions for xylanase production were obtained as fermentation time 72 h, concentration of 0.08% for MgSO4, fermentation temperature 37.3 °C, and the xylanase activity increased from 107.6 to 269.4 IU/mL, which was a 150% increase. It was found that the higher temperature (37.3 °C) was more suitable for xylanase production than low temperature (30.0 °C) in T. orientalis EU7-22. The statistical experimental design was proven as an effective method to obtain optimum parameters for xylanase production. The mixture of corn cobs and wheat bran as substrates could greatly improve the xylanase yield, in comparison with corn cobs alone, wheat bran alone, and Avicel supplement with wheat bran as inducer substrates, respectively.