Secretion to the growth medium of an alpha-amylase by Escherichia coli clones carrying a Bacillus laterosporus gene

alpha-Amylase gene from Bacillus laterosporus P-3 was cloned and expressed in Escherichia coli HB101 and DH5 alpha. Up to 92% of the cloned gene produ ct was secreted into the medium by the recombinant E. coli. The recombinant crude enzyme showed improved functionality in terms of activity at a wider pH range and at higher temperature, as compared to the crude enzyme from t he donor strain. The improved functionality of the cloned enzyme was due to the absence of a contaminating protease which was co-produced in the donor strain. Sub-cloning of the alpha-amylase gene using the promoter-probe vec tor, pKT240 in E. coli DH5 alpha indicated the presence of a promoter of B. laterosporus P-3 in the cloned fragment.