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

Abstract

A halophilic α-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 °C and pH 7.0. When 2% (w/v) soluble starch was used as substrate, the specific activity was about 1,090 U mg(-1) protein. This is the first report on identifying a halophilic α-amylase with high specific activity from non-halophilic bacteria.