Selection of high- yield thermostable protease producing strain by ARTP and the study on its enzymological properties

In order to obtain an industrial strain with higher thermostable protease production,the original strain of Bacillus licheniformis TP1 was mutated by atmospheric and room temperature plasmas. A good genetic stability strain TP1- 5 was screened from the mutants,which produced 33200 U / m L from initial 21300 U / m L of the thermostable protease.The protease was purified by ethanol precipitation and anion exchange chromatography to electrophoretic homogeneity. The purified protease had a good p H stability and thermal stability,with optimal temperature and p H was 60℃ and 10.0. The protease also exhibited high stability towards surfactants such as SDS,Tween-80,Triton X-100 et al.