Results and discussion
3.1. Optimization of fermentation parameters by response surface methodology using Box-Behnken design
Based on results of preliminary experiments (traditional method of optimization one factor at a time), the levels of media components were set to give maximum yields of cellulase. The results of a 27 - run BBD with four variables substrate concentration 3–7 g, moisture ratios of 1:3–1:9, inoculum sizes of 103–107 and initial pH of 3–7 chosen for optimization of fungal cellulases are shown in Table 2. Filter paper activity varied distinctly under the conditions tested. For each run, the experimental responses long with the predicted response calculated from the regression equation (Eq. (3)) are shown in Table 2.