Improving the bacillomycin L production in Bacillus amyloliquefaciens by atmospheric and room-temperature plasma combined with Box-Behnken design.

Bacillomycin L, a cyclic lipopeptide derived from Bacillus amyloliquefaciens, has great potential for developing biochemical phytofungicides. In this study, a mutant M86 with high anti-Botrytis cinerea activity was obtained by atmospheric and room-temperature plasma (ARTP) mutagenesis from the original strain 1841, with bacillomycin L yield increasing from 244.22 to 415.89 mg/L. Mass spectrometry analysis identified that the main active compounds were C14-, C15-, and C16-bacillomycin L. Re-sequencing M86 showed that ARTP mutagenesis resulted in the effective mutations in sigma factors and ABC transporter proteins. Transcriptome sequencing further revealed the significant up-regulation of the bmyDABC and ytrBCC2DEF gene cluster involved in bacillomycin L synthesis and transporter, respectively, in M86. Bacillomycin L yield was further boosted to 676.47 mg/L after optimizing the fermentation medium by adjusting glycine, serine, and K₂HPO₄ concentrations. Bacillomycin L exhibited broad inhibitory activity against 17 fungi and nine bacterial species. This investigation provides a foundation for bacillomycin L production and application.