β-葡萄糖苷酶的异源表达及与纤维素酶协同酶解竹纤维

在毕赤酵母GS115中表达东方肉座菌EU7-22的β-葡萄糖苷酶基因（bgl?），获得基因工程菌株BP17。优化BP17发酵产酶条件后，重组β-葡萄糖苷酶活力达121 IU/mL。酶学性质研究表明，该酶最适反应温度为70℃，在60℃以下有较好的热稳定性；最适催化pH为5.0，在pH 3.0 ~ 8.0之间有较好的稳定性。将异源表达的β-葡萄糖苷酶添加到东方肉座菌的纤维素酶液中协同降解经过预处理的竹纤维，当纤维素酶添加量为FPA 20 IU/g底物，β-葡萄糖苷酶添加量为BG 6 IU/g底物时，纤维二糖浓度显著下降，酶解得率达到83.03%，表明重组β-葡萄糖苷酶的加入更有利于纤维素的酶解糖化。

Heterologous Expression of the β-Glucosidase and Its Synergistic Hydrolysis of Bamboo with Cellulase

The β-glucosidase gene (bglI) from Hypocrea orientalis EU7-22 was cloned and effectively expressed in Pichia pastoris GS115. The ß-glucosidase activity expressed by recombinant strain BP17 reached 121 IU/mL. The expressed ß -glucosidase exhibited the optimum catalytic activity at 70°C and pH 5.0. The enzyme exhibited good stability at pH 3.0 ~ 8.0 and remained 65% of its original activity after 1 h at 60°C. The pretreated bamboo cellulose was synergistic hydrolyzed by the cellulases from Hypocrea orientalis EU7-22 and the recombinant β-glucosidase from strain BP17. Supplementing recombinant β-glucosidase greatly reduced the inhibitory effect caused by cellobiose, and the hydrolysis yield was improved to 83.03% with enhanced β-glucosidase activity of 6 IU/g substrate. The results indicated the recombinant β-glucosidase significantly boost the efficiency of saccharification.