A Bacillus subtilis secretion vector system derived from the B. subtilis alpha-amylase promoter and signal sequence region, and secretion of Escherichia coli beta-lactamase by the vector system.

A secretion vector system in Bacillus subtilis was constructed from the alpha-amylase promoter and signal sequence coding region of an alpha-amylase hyperproducing strain, B. subtilis NA64, and the major part of the plasmid pTUB4 which was derived from pUB110. When an Escherichia coli beta-lactamase gene, lacking its own promoter and signal sequence coding region, was introduced into the secretion vector system, beta-lactamase was expressed in B. subtilis. In addition, more than 95% of the enzyme synthesized was secreted into the culture medium via the secretion vector system. Secreted beta-lactamase crossreacted with rabbit antiserum raised against the E. coli enzyme.