ComQXPA Quorum Sensing Dynamic Regulation Enhanced Fengycin Production of <i>Bacillus subtilis</i>

Fengycin is an antifungal drug that could be used as a biocontrol agent if it could be produced in high amounts. The ComQXPA quorum sensing (QS) system is a natural mechanism, regulating cell density-dependent behaviors in <i>Bacillus subtilis</i>. This study employed the QS-targeted promoter <i>P</i>_<i>srfA</i> to express the <i>pps</i> gene cluster in <i>B. subtilis</i>, coupling the ComQXPA system to produce fengycin. Mutations in the ComA regulatory protein-binding site RE3 exhibited a 2.45-fold increase in promoter expression intensity and resulted in an elevation of fengycin production from 489 to 1832 mg/L, a 2.74-fold enhancement. Transcriptomic analysis revealed the upregulation of genes associated with carbon source uptake and utilization and metabolic pathways related to amino acids and fatty acids, which are precursors for fengycin synthesis. Additionally, knockout of <i>rapJ</i> and <i>rapE</i> increased fengycin production to 3190 mg/L. In a coculture system constructed with <i>Corynebacterium glutamicum</i>, fengycin production reached 4005 mg/L. This work provides a strategy for dynamically regulating fengycin synthesis.