Combinatorial mutagenesis of Bacillus amyloliquefaciens for efficient production of protease

Abstract

As an important industrial enzyme, protease is widely used in feed, food and other fields. At present, the insufficient protease activity obtained from microorganisms cannot meet the purpose of industrial production. In this study, Bacillus amyloliquefaciens with high protease production was screened from animal feces by plate transparent circle method. To improve the production of protease, atmospheric room temperature plasma (ARTP) mutagenesis was used in the first round, protease activity reached 315.0 U/mL. Then, to enhance production of protease, 60Co-γ irradiation was used for combined mutagenesis, leading to protease activity of B. amyloliquefaciens FMME ZK003 up to 355.0 U/mL. Furthermore, to realize the efficient production of protease, after optimization of fermentation conditions, protease activity was increased to 456.9 U/mL. Finally, protease activity of B. amyloliquefaciens FMME ZK003 reached 823.0 U/mL in a 5 L fermenter. These results indicate that B. amyloliquefaciens can efficiently produce protease, which provides a good foundation for the industrial production of protease.