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

Plipastatin is a cyclic lipopeptide synthesized by non-ribosomalpeptide synthetases (NRPS), which has a diverse range of applicationsin 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 andchallenging to synthesize, significantly limiting its production andapplication. ComQXPA-P-srfA, a quorum-sensing (QS) circuitfrom Bacillus amyloliquefaciens, wasconstructed in this study. Two QS promoters MuP(srfA) andMtP(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 promoterto achieve the dynamic regulation of plipastatin, which increasedthe yield of plipastatin by 3.5 times. Integrating ComQXPA into plipastatinmono-producing M-24:MtP(srfA) increased the yield of plipastatinto 3850 mg/L, representing the highest yield reported to date. Fournew plipastatins were identified via UPLC-ESI-MS/MSand GC-MS analysis of fermentation products of mono-producingengineered strains. Among them, three plipastatins contained two doublebonds in the fatty acid side chain, representing the first exampleof a new type of plipastatin. Our results indicate that the QS systemComQXPA-P-srfA of Bacillus can dynamicallyregulate plipastatin production, and the pipeline could be extendedto the other strains to regulate target products dynamically.