β-葡萄糖苷酶与外切葡聚糖酶的克隆表达及协同水解效应OA

The utilization of lignocellulose,a green alternative to fossil fuels,is restricted by issues such as insufficient catalytic efficiency of cellulases in degrading crystalline cellulose and poor stability of multi-enzyme synergistic system.In order to solve such problems,a recombinant expression system pET28a(+)-BL21(DE3)was constructed after the β-glucosidase(BGL)gene bglZ and the exoglucanase(EXG)cbH were cloned from Bacillus amyloliquefaciens and Bacillus altitudinis,respectively.The recombinant enzyme was obtained with high purity through IPTG induced expression and nickel column purification.According to enzymatic characterization studies,the optimal reaction conditions for these two enzymes were pH 5.0 and 40 ℃.In addition,the optimal cellulose decomposition was observed when BGL and EXG were combined in a 3∶1 ratio.More importantly,the enzyme could still maintain over 70％of its activity after the reaction proceeded at 40℃for 105 minutes.It is worth noting that BGL could effectively alleviate the product inhibition of EXG by decomposing cellobiose,and the degradation efficiency was significantly improved due to the synergistic effect of dual enzymes.Our research work provides an efficient enzymatic hydrolysis scheme for biomass energy conversion,which is of great significance for achieving carbon neutrality goals.