LAUSR

Abstract In this study, the effects of carbon source, nitrogen source, and metal ions on cell growth and Bacillus aryabhattai β-amylase production in recombinant Brevibacillus choshinensis were investigated. The optimal medium for β-amylase production, containing glucose (7.5 g·L−1), pig bone peptone (40.0 g·L−1), Mg2+ (0.05 mol·L−1), and trace metal elements, was determined through single-factor experiments in shake flasks. When cultured in the optimized medium, the β-amylase yield reached 925.4 U mL−1, which was 7.2-fold higher than that obtained in the initial medium. Besides, a modified feeding strategy was proposed and applied in a 3-L fermentor fed with glucose, which achieved a dry cell weight of 15.4 g L−1. Through this cultivation approached 30 °C with 0 g·L−1 initial glucose concentration, the maximum β-amylase activity reached 5371.8 U mL−1, which was 41.7-fold higher than that obtained with the initial medium in shake flask.