LAUSR

This work isolated a strain named Bacillus amyloliquefaciens HM618 from soil, which can inhibit the growths of Botrytis cinerea, Rhizoctonia solani, and Escherichia coli DH5α. Based on the results of Response Surface Methodology (RSM), the surfactin levels of strain HM618 were elevated from 0.724 to 1.876 g/L and 0.995 to 1.888 g/L under the pure culture with the optimized medium (containing 62.39 g/L sucrose, 15.06 g/L yeast extracts, and 3.27 g/L aspartate) and under the co-culture of strains HM618 and Bacillus subtilis 168 with the optimized medium (containing 50.52 g/L sucrose, 19.76 g/L yeast extracts, and 1.02 g/L glutamate), respectively. Additionally, influences of non-constitutive amino acids involved in the biosynthesis of surfactin were also explored. The highest surfactin level reached 2.04 g/L after adding 3.0 g/L exogenous ornithine. However, the surfactin production of strain HM618 was significantly inhibited after adding the mixtures of non-constitutive amino acids. B. amyloliquefaciens HM618 displayed antimicrobial activity and produced surfactin Optimized medium by Response Surface Methodology increased surfactin level The pathways involved in surfactin production of strain HM618 were analyzed The surfactin level reached 2.04 g/L by adding 3.0 g/L exogenous ornithine The mixtures of non-constitutive amino acids inhibited surfactin production This article is protected by copyright. All rights reserved.