Optimization of fermentation conditions of lipopeptide-producing Bacillus amyloliquefaciens HY2-1

Bacillus amyloliquefaciens HY2-1 is the previously isolated marine microorganism that can produce lipopeptides such as fengycins and surfactants. In order to improve the antimicrobial activity of lipopeptides by strain HY2-1, using the bacterial inhibition zone diameter as response value, the carbon and nitrogen sources of the fermentation medium and fermentation conditions of strain HY2-1 were optimized by single-factor and response surface test design. The results showed that the optimum carbon and nitrogen sources for the fermentation medium of strain HY2-1 were soluble starch 80 g/L, yeast extract powder and peptone (1:1) 10 g/L, and the optimal fermentation conditions were loading volume 50 ml/250 ml, fermentation time 48 h, inoculum 1% and rotation speed 200 r/min. Under these conditions, the inhibitory circle diameter of strain HY2-1 fermentation broth on Penicillium digitatum was (18.6±0.1) mm, which was 26.5% higher than that of before optimization (14.7±0.5) mm. Through the optimization of carbon and nitrogen sources of fermentation medium and fermentation conditions, the antibacterial inhibitory activity of HY2-1 lipopeptides was significantly improved.