Production optimization and functional characterization of thermostable β-mannanase from Malbranchea cinnamomea NFCCI 3724 and its applicability in mannotetraose (M4) generation

The thermophilic fungus Malbranchea cinnamomea NFCCI 3724 produced significant level of beta-mannanase when grown on copra meal 131 U/gds. In solid state fermentation, parameters namely pH, moisture content and carbon supplement were optimized by response surface methodology. Optimized conditions suggested by rotatable central composite design were: pH (7.75), moisture content (12.7 ml), and carbon supplement (86.7 mg) leads to five-fold increase in beta-mannanase production of 669 U/gds. Purified beta-mannanase from M. cinnamomea had molecular mass of similar to 60 kDa on SDS-PAGE.-Mannanase was optimally active at 70 degrees C and in the pH range 4.0-6.0. The enzyme was thermostable at 60 degrees C and had halflife of 8 h. The specific activity of purified beta-mannanase was 57.2 U/mg with K-m and V-max as 4 mg/ml and 63 mu mol/ml/min, respectively. M. cinnamomea mannanase was found to be effective for hydrolysis of locust bean and konjac gum. The end product analysis showed mannotetraose (M4) as the major product with conversion efficiency of 27% on locust bean gum (LBG) and 30% on konjac gum. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.