Statistical optimization of xylanase production by Aspergillus niger AN-13 under submerged fermentation using response surface methodology

Response surface methodology (RSM) was performed to evaluate the effects of cultivation time, pH and substrate concentration on production of xylanase by Aspergillus niger AN-13. Agricultural residuewheat bran was used as main substrate under submerged fermentation. Xylanase production was optimized by Box-Behnken design (BBD). Statistical analysis of results showed that, the linear andquadric terms of these three variables had significant effects, and evident interactions existing between pH and substrate concentration were found to contribute to the response at a significant level.Furthermore, Box-Behnken design (BBD) used for the analysis of treatment combinations gave a second-order polynomial regression model, which was in good agreement with experimental results,with R2=0.9959 (