Statistical optimization of alkaline xylanase production from Streptomyces violaceoruber under submerged fermentation using response surface methodology

Abstract

Response surface methodology employing central composite design (CCD) was used to optimize fermentation medium for the production of cellulase-free, alkaline xylanase from Streptomyces violaceoruber under submerged fermentation. The design was employed by selecting wheat bran, peptone, beef extract, incubation time and agitation as model factors. A second-order quadratic model and response surface method showed that the optimum conditions for xylanase production (wheat bran 3.5 % (w/v), peptone 0.8 % (w/v), beef extract 0.8 % (w/v), incubation time 36 h and agitation 250 rpm) results in 3.0-fold improvement in alkaline xylanase production (1500.0 IUml(-1)) as compared to initial level (500.0 IUml(-1)) after 36 h of fermentation, whereas its value predicted by the quadratic model was 1347 IUml(-1). Analysis of variance (ANOVA) showed a high coefficient of determination (R(2)) value of 0.9718, ensuring a satisfactory adjustment of the quadratic model with the experimental data.The economical and cellulase-free nature of xylanase would enhance its applicability in pulp and paper industry.