中文摘要：

从1株快速水解乳糖发酵产酸的凝结芽孢杆菌NL01的基因组上克隆获得了1个新的β-半乳糖苷酶基因,该基因长度为1 998 bp,其编码的氨基酸序列与已经报道的β-半乳糖苷酶相似度低于40%。将该β-半乳糖苷酶基因整合到表达载体pETDuet-1上,并在大肠杆菌BL21（DE3）中进行重组表达,β-半乳糖苷酶粗酶酶活为119.0μmol/（min·mg）,经镍柱纯化获得的重组β-半乳糖苷酶酶活为666.4μmol/（min·mg）。利用该重组β-半乳糖苷酶水解乳糖,经TLC和HPLC分析显示该酶具有将乳糖水解为葡萄糖和半乳糖的活力,是一种新型的β-半乳糖苷酶。

英文摘要：

A novel β-galactosidase gene was cloned fromBacillus coagulansNL01 which had ability to hydrolyze lactoseinto glucose and galactose in this study. The length of the β-galactosidase gene was 1 998 bp, and its coding sequenceshowed very low identity with other reported β-galactosidase. The gene was cloned into pETDuet-1 and expressed inEscherichia coliBL21（DE3）. The crude enzyme activity was 119.0 μmol/（min·mg）, and the purified enzyme activitywas 666.4 μmol/（min·mg） after Ni-NTA purification. It was indicated from the analysis results of the hydrolysis prod-uct obtained by the purified β-galactosidase that this novel β-galactosidase presented high activity toward lactose con-version into glucose and galactose.