关键词: 葡聚糖内切酶, 大肠杆菌, 短小芽孢杆菌, 基因, 克隆, 表达

Abstract:

β-1,4-endoglucanase encoding gene was cloned from Bacillus pumilus H9 producing alkaline cellulase, with its sequence and domain being also analyzed. Then, the gene was cloned into Escherichia coli （E. coli） prokaryotic expression vector pET20b, and the construct pET20b-EglA was transformed to a E. coli BL21 （DE3） strain. Finally, by using the SDS-PAGE electrophoresis, the expressed product was detected. Experimental results show that （ 1 ） the β-1,4-endoglucanase gene sequence, 1980 bp in size with 659 amino acids being coded, is effectively expressed in E. coli; （2） the β-1,4-endoglucanase with a relative molecular mass of about 73 000 consists of two discontinuous domains： one is an N-terminal catalytic domain belonging to the glycoside hydrolase family 9 and the other is a C-terminal cellulose-binding domain belonging to the carbohydrate 3; and （3） the activity and stability of the recombinant β-1,4-endoglucanase at different temperatures and pH values are both close to those of the original strain.

Key words: endoglucanase, Escherichia coli, Bacillus pumilus, gene, cloning, expression