Application of response surface methodology in medium optimization for spore production of Coniothyrium minitans in solid-state fermentation

Spore production of Coniothyrium minitans was optimized by using response surface methodology (RSM), which is a powerful mathematical approach widely applied in the optimization of fermentation process. In the first step of optimization, with Plackett - Burman design, soluble starch, urea and KH2PO4 were found to be the important factors affecting C. minitans spore production significantly. In the second step, a 2 3 full factorial central composite design and RSM were applied to determine the optimal concentration of each significant variable. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the critical components for the maximum were obtained as follows: soluble starch 0.643 ( 36.43 g. l(-1)), urea -0.544 (3.91 g l(-1)) and KH2PO4 0.049 ( 1.02 g l(-1)) with a predicted value of maximum spore production of 9.94 x 10(9) spores/g IDM. Under the optimal conditions, the practical spore production was 1.04 x 10(10) spores/g IDM. The determination coefficient (R-2) was 0.923, which ensure an adequate credibility of the model.