芽孢杆菌β-淀粉酶基因在大肠杆菌中的克隆与表达

Cloning of β-Amylase Gene from B. substitute and Its Expression in E. coli

本工作采用新设计的营养缺陷型淘汰筛选法,从本实验室筛选的芽孢杆菌Bacillus R2中分离到能够水解生淀粉的β-淀粉酶基因。该基因所在的DNA片段为5.25kb,在大肠杆菌(E.coli)中的表达产物具有与供体菌相同的淀粉酶特性,实验室条件下酶产量为500IU/ml以上,RDA值为57%,并且可以全部分泌到培养基中。

The gene coding for β-amylase with raw starch-digestion ability was isolated from B. substitute R2 which was selected in this lab. The procedure used in this scireening was developed in this work by the method named nutrition-restriction. The DNA fragment containing the β-amylase gene was 5.25 kb in length. There was no diffevence in enzymological properties between the β-amylase produced by the gene-donor strain and the expression product of E. colt. The yield of the cloned β-amylase was over 500 IU/ml in our labratory culture condition, the RDA value was 57%, and all of this enzyme were found to be secreted into medium.