Optimization of Fermentation Conditions of Bacillus 25-2 for Cellulase Production by Response Surface Methodology

In order to enhance cellulase-producing capacity of Bacillus 25-2,response surface method was applied to optimize its fermentation conditions.Firstly,two level factorial design of Plackett-Burman was used to evaluate the effects of six related factors on cellulase activity.Three factors including fermenting time(X1),fermentation temperature(X2) and initial pH value(X3),as the significant factors influencing cellulase activity,were screened out.Then the path of steepest ascent experiments were adopted to approach the optimal region of fermentation conditions,Box-Behnken design and response surface methodology(RSM) analysis were applied to analyze the relationships between these factors and to find out the optimal values of the critical factors.Then second-order regression equation model was further establish and the optimal conditions of the three factors were assessed by RSA as follows: 21.7 h of fermenting time,fermentation temperature was at 46 ℃,and initial pH value was 4.8.Under the above conditions,the activity of cellulase increased nearly 1.704 times than before to 27.907 U/mL and the experimental values agreed with the predicted values.