Production, purification, and characterization of carboxymethyl cellulase from novel strain Bacillus megaterium

Abstract

In the present investigation a strain of Bacillus megaterium BM05 was evaluated for cellulase production in submerged fermentation using wheat straw as a substrate. Various nutritional and cultural parameters were optimized to obtain maximum production of carboxymethyl cellulase. The strain produced best titer of cellulase at initial medium pH of 5, inoculum size of 1% using 2% wheat straw with 0.8% NaCl in medium for 48 h of fermentation period. Further supplementation of CMC as an additional carbon source and yeast extract as nitrogen sources favored enzyme production. Organic acids found to be inhibitory effect on secretion of cellulase enzyme by B. megaterium BM05. The enzyme exhibited molecular weight of 53.55 kDa as revealed by SDS‐PAGE. The enzyme had optimum pH and temperature of 6.5°C and 50°C with stability range of 6.0–8.0 and 30°C–40°C for 140 min, respectively. The enzyme had half life of 38.9 min at 80°C. Metal profile of the enzyme indicated that K+ (125%) and Na+ (118%) were the activators while Pb+2 (15%) and Hg+2 (13%) were the inhibitors. The endoglucanase had Km and Vmax value of 1.73 and 0.95 U/mL using CMC‐Na as a substrate, respectively. Turnover number (Kcat) and catalytic efficiency (Kcat/Km) of purified enzyme was 1556.11 min and 1.3 × 106 M/s, respectively. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1741–1749, 2016