Effect and regulation of fatty acids on bacillomycin D synthesis

Bacillomycin D is a cyclic antimicrobial lipopeptide that has excellent antifungal effects, but its application is limited due to its low yield. At present, it is not clear whether fatty acids regulate the synthesis of bacillomycin D. Therefore, the effects of nine fatty acids on the yield of bacillomycin D produced by Bacillus amyloliquefaciens fmbJ were studied. The results showed that sodium propionate, propionic acid, and butyric acid could increase the yield of bacillomycin D by 44, 40, and 10%, respectively. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression levels of bacillomycin D synthesis gene, signaling factors and genes related to fatty acid metabolism, so as to explore the mechanism of sodium propionate regulating bacillomycin D synthesis. In conclusion, sodium propionate could accelerate the tricarboxylic acid cycle and promoted spore formation, cell movement, the secretion of extracellular protease and the transcription of bacillomycin D synthesis gene by upregulating the expression of signal factors degU, degQ, sigH, sigM and spo0A and ultimately promoted the synthesis of bacillomycin D. In this study, the mechanism of sodium propionate increasing bacillomycin D production was explored from multiple perspectives, which provided theoretical support for the large-scale production of bacillomycin D and was expected to promote its wide application in food, agriculture and medicine fields.