Inhibition mechanism of quorum sensing and biofilm formation of <i>Pseudomonas fluorescens</i> by a novel quorum quenching bacteria <i>Lactiplantibacillus plantarum</i> YP4-1-2

<i>Pseudomonas fluorescens</i> is a widespread spoilage bacterium in food, and its spoilage characteristics and biofilm formation are regulated by <i>N</i>-acyl-homoserine lactone (AHLs) quorum sensing (QS) system. Quorum quenching (QQ) is considered as an effective strategy to control the spoilage bacteria. Therefore, this study revealed a new QQ bacteria <i>Lactiplantibacillus plantarum</i> YP4-1-2. Notably, the crude cell extract (CCE) from <i>L</i>. <i>plantarum</i> YP4-1-2 showed strongly QQ activity against the AHLs of <i>P</i>. <i>fluorescens.</i> The degradation rate of AHLs (<i>N</i>-octanoyl-<i>L</i>-homoserine lactone) reached 25.90%, 78.57% and 100% at the CCE protein concentrations of 57, 86 and 114 μg/mL, respectively. In addition, the CCE could drastically reduce the formation of biofilm, bacterial motility (swimming and swarming), and the release of extracellular protease and biogenic amines of <i>P</i>. <i>fluorescens</i>. Real-time polymerase chain reaction (PCR) results revealed that the CCE downregulated QS-related genes (<i>rhlI</i>, <i>rhlR</i>, <i>aprX</i>, <i>algA</i>, <i>orm</i>, <i>flgA</i>, and <i>ldcA</i>). Finally, using whole-genome sequencing analysis, the active substance in the CCE was identified to be penicillin V acylase (PVA) and named <i>Lp</i>PVA. Meanwhile, homologous modeling and molecular docking analysis showed that the binding effect of <i>Lp</i>PVA on long-chain AHLs was better than that on short-chain AHLs. This study demonstrated that <i>L</i>. <i>plantarum</i> YP4-1-2 could be considered as a promising QS inhibitor and antibiofilm agent against foodborne spoilage bacteria.