Identification of a halophilic alpha-amylase gene from Escherichia coli JM109 and characterization of the recombinant enzyme.

摘要

A halophilic alpha-amylase (EAMY) gene from Escherichia coli JM109 was overexpressed in E. coli XL10-Gold and the recombinant protein was purified and characterized. The activity of the EAMY depended on the presence of both Na+ and Cl-, and had maximum activity in 2 M NaCl at 55 degrees C and pH 7.0. When 2 % (w/v) soluble starch was used as substrate, the specific activity was about 1090 U mg-1 protein. This is the first report on identifying a halophilic alpha-amylase with high specific activity from non-halophilic bacteria