Phytol inhibits quorum sensing and biogenic amine production in Pseudomonas fluorescens PF12

Pseudomonas fluorescens is a prevalent spoilage bacterium in various chilled aquatic products, producing toxic biogenic amines (BAs) through the decarboxylation of amino acids via amino acid decarboxylases. Our previous studies revealed that P. fluorescens PF12 regulates BA production through its quorum sensing (QS) system, suggesting that disrupting QS could be a potential approach to control BA generation. In this study, we targeted the three-dimensional structure of the LuxI-type protein in P. fluorescens PF12 to screen for QS inhibitors (QSIs) through high-throughput screening from Seaweed Metabolite Database and Comprehensive Marine Natural Products Database. Nine compounds with high binding scores to the LuxI-type protein were identified. Considering cost-effectiveness and safety, phytol was selected for further investigation. Experimental results demonstrated that sub-inhibitory concentrations of phytol significantly suppressed BA production, siderophore production, motility, extracellular protease secretion, and biofilm formation in P. fluorescens PF12. Specifically, when the salmon fillets were stored for 288 h, the histamine content in the fillets treated with 25 mg/mL phytol decreased by 43.81 %. RT-qPCR revealed that the expression levels of key genes hisD and hisC related to histamine synthesis in the phytol treatment group were reduced by 7.68 ( p  < 0.05) and 8.23 % ( p  < 0.05), respectively, compared to the control group. Molecular docking analysis revealed that phytol interacts with key residues in the LuxI-type protein, thereby blocking the synthesis of acyl-homoserine lactones (AHLs) and downstream QS signaling. These findings indicate that phytol has great potential for controlling BA production in aquatic products and ensuring food safety.