Response surface optimization of xylanase production by indigenous thermoalkalophillic Bacillus sp.

Xylanases are an important class of hydrolytic enzymes with a wide range of industrially important applications especially in paper and pulp industry. The present study aimed to take the advantage of statistical approach of optimization to investigate the interactive effects of prominent process factors involved in xylanase production. A novel bacterial isolate Bacillus sp. MCC 2727 was isolated from soil possessing xylanase producing ability at alkaline pH (9.2) and optimum temperature of 50°C. Using the conventional one-factor-at-a-time method, low cost agricultural waste; wheat bran, combination of peptone and yeast extract served as best carbon and nitrogen sources, respectively. MgSO4 as metal salt and xylan as additive increased the xylanase productivity. Central composite design and response surface methodology were used to optimize these significant process parameters and for evaluation of interactive factors. Maximum xylanase activity of 205.3 IU/ml was obtained with 5% wheat bran, 1% each of yeast extract, peptone, xylan and MgSO4 which was in consensus with the predicted value (207.2 IU/ml) which proved the validity and the accuracy of the statistical approach of optimization.