Characterization of produced xylanase by Bacillus subtilis D3d newly isolated from apricot phyllosphere and its potential in pre-digestion of BSG

Bacillus subtilis D3d newly isolated from apricot phyllosphere has the potential of producing high levels of xylanase. The present study used response surface methodology (RSM) to optimize catalytic activity. Factors including temperature, pH and beechwood xylan concentration were optimized using central composite design (CCD). Under optimized condition maximum xylanase activity found 260 U/ml. The enzyme showed stability over a range of pH (5.0-9.0) and exhibited more than 80% activity after 72 hat 40 degrees C. Such RSM models as well as stability data can be used at different operational conditions to predict the residual catalytic activity. Regard to pre-digested brewer's spent grain (BSG) has potential as a valuable poultry B. subtilis D3d crude xylanase. Maximum reducing sugar yield were found to be 68.43 mg(reducing) (sugars)/g(BSG) at optimum condition. The results revealed that B.subtilis D3d is a promising xylanase-producing bacterium with great potential for use in the food and feed industries. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.