Characterization of novel EGs reconstructed from Bacillus subtilis endoglucanase

Bacterial cellulases have taken on satisfactory application performance and economic value in detergent industry. Neutral endoglucanase (EG1) gene was cloned from Bacillus subtilis and expressed Pichia pastoris in our previous study. Redesigned endoglucanases enhanced cellulase domain, added and deleted carbohydrate-binding module (CBM), named EG2, EG3, and EG4, respectively, were constructed in this study. The redesigned EG genes were expressed in P. pastoris, and their characters were also discussed. The optimal temperature and pH value of the all EGs was 65 °C and 6.0, respectively, where their enzymatic activities in P. pastoris cultivation supernatant reached 867, 651, 966, and 881 U/mL. EG2 showed 24.9 % enzymatic activity loss compared to natural endoglucanase. EG4 showed specific activity 30 % loss and thermostability decrease compared to EG1, which suggested CBM played an important role in improving the catalytic power and heat stability of cellulase family which attached. The specific activity of EG2 and EG3 showed similar to EG1, which suggested neither enhancement of CD nor CBM to endoglucanase can improve its catalytic power, which might rest with its intact topologic structure.