Cloning and expression of a serine proteinase gene from Thermoactinomyces sp. in Bacillus subtilis cells

: A gene coding for thermostable serine protease from Thermoactinomyces sp. K50 is cloned and expressed in Bacillus subtilis cells. Restriction map of cloned DNA fragment is determined. Thermostability and temperature optimum of proteolytic activity of the cloned gene product are lower than those of the natural proteinase of Thermoactinomyces sp. K50. Serine protease, a product of cloned gene, is highly sensitive to proteolysis and its degradation can be prevented by Ca2+ ions.