Aim: In the study, we investigated the regulatory effects of these genes (codY, comA, degU and spo0A) on the biosynthesis of three lipopeptides (bacillomycin D, fengycin and surfactin) in Bacillus amyloliquefaciens.
Methods and results: The codY, comA, degU and spo0A genes in B. amyloliquefaciens fmbJ were knocked out. The results showed that the productions of bacillomycin D were significantly reduced compared with that of fmbJ. Their deletion induced great changes in the levels of transcripts specifying metabolic pathways, quorum sensing system and substance transport system in fmbJ. Moreover, overexpression of these genes improved the productions of bacillomycin D. In particular, the overexpression of spo0A enhanced bacillomycin D yield up to 648·9 ± 60·9 mg l-1 from 277·3 ± 30·5 mg l-1 . In addition, the yields of surfactin in fmbJΔcodY and fmbJΔdegU were significantly improved, and the regulatory factor CodY had no significant effect on the synthesis of fengycin.
Conclusions: These genes positively regulated the expression of bacillomycin D and fengycin synthase genes in strain fmbJ. However, codY and degU negatively regulated surfactin biosynthesis. Moreover, it was found that CodY had a concentration dependence on bacillomycin D synthesis. Spo0A might play a direct regulatory role in the synthesis and secretion of bacillomycin D.
Significance and impact of the study: This study indicated that genetic engineering of regulatory genes was an effective strategy to improve the yields of antimicrobial lipopeptides and provided promising strains for industrial production of lipopeptides.
Keywords: Bacillus amyloliquefaciens; knockout and overexpression; lipopeptides; transcriptional regulatory genes; transcriptomics.
© 2021 The Society for Applied Microbiology.