Research on the Regulation of Plipastatin Production by the Quorum-Sensing ComQXPA System of Bacillus amyloliquefaciens

Plipastatin is a cyclic lipopeptide synthesized by non-ribosomal peptide synthetases (NRPS), which has a diverse range of applications in postharvest preservation of fruits and vegetables, biological control, and feed processing. Whereas the yield of plipastatin in wild Bacillus sp . is low, its chemical structure is complex and challenging to synthesize, significantly limiting its production and application. ComQXPA-P srfA, a quorum-sensing (QS) circuit from Bacillus amyloliquefaciens, was constructed in this study. Two QS promoters MuP srfA and MtP srfA, with 35 and 100% increased activity, respectively, were obtained by mutating the original promoter P srfA . Thus, the natural promoter of plipastatin was replaced by a QS promoter to achieve the dynamic regulation of plipastatin, which increased the yield of plipastatin by 3.5 times. Integrating ComQXPA into plipastatin mono-producing M-24:MtP srfA increased the yield of plipastatin to 3850 mg/L, representing the highest yield reported to date. Four new plipastatins were identified via UPLC-ESI-MS/MS and GC–MS analysis of fermentation products of mono-producing engineered strains. Among them, three plipastatins contained two double bonds in the fatty acid side chain, representing the first example of a new type of plipastatin. Our results indicate that the QS system ComQXPA-P srfA of Bacillus can dynamically regulate plipastatin production, and the pipeline could be extended to the other strains to regulate target products dynamically.