Molecular cloning of a thermostable neutral protease gene from Bacillus stearothermophilus in a vector plasmid and its expression in Bacillus stearothermophilus and Bacillus subtilis

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Abstract
The structural gene for a thermostable protease from B. stearothermophilus was cloned in plasmid pTB90. It is expressed in B. stearothermophilus and B. subtilis. B. stearothermophilus carrying the recombinant plasmid produced .apprx. 15-fold more protease (310 U/mg of cell dry wt) than did the wild-type strain of B. stearothermophilus. Some properties of the proteases that were purified from the transformants of B. stearothermophilus and B. subtilis were examined. No significant difference was observed among the enzyme properties studied here despite the difference in host cells. The protease, neutral in pH characteristics and with a MW of 36,000, retained about 80% of its activity even after treatment of 65.degree. C for 30 min.