An E. coli expression system for the extracellular secretion of barley alpha-amylase

Libraries of modified genes are often screened during the process of genetically engineering enzymes with specifically tailored activities. It is important, therefore, to create expression systems which allow for the rapid screening of many clones. We developed an Escherichia coli expression system which will secrete enzymes into the growth medium. We describe the first reported expression of barley alpha-amylase in E. coli. The enzyme is secreted onto solid media containing starch to produce easily visualized halos. In addition, the enzyme is secreted into liquid media in an intact, active form.