Two Novel AHL-Degrading Enzymes, PoAcy1 and PoLac, Attenuate Pectobacterium carotovorum and Pseudomonas aeruginosa Virulence through Quorum-Sensing Disruption.

Ensuring food safety remains a significant challenge due to the persistent contamination and spoilage caused by biofilm-forming and resistant pathogenic bacteria. Quorum quenching presents an ecofriendly control strategy. We identified a novel acylase (PoAcy1) and a broad-spectrum lactonase (PoLac) from marine-derived bacterium Pseudooceanicola onchidii XY-99. Both the XY-99 strain and purified PoLac effectively suppressed Pectobacterium carotovorum subsp. carotovorum (Pcc)-induced soft rot in potato tubers. Heterologous expression of either enzyme in Pseudomonas aeruginosa PAO1 significantly attenuated key quorum-sensing (QS)-dependent virulence traits, including biofilm formation, pyocyanin production, and hemolytic activity. This suppression was associated with downregulation of the core QS regulator genes and biofilm-associated genes. Together, PoAcy1 and PoLac─exhibiting distinct substrate specificities toward short- and long-chain AHLs─expand the repertoire of marine-derived quorum-quenching enzymes for targeted disruption of QS in foodborne pathogens such as P. aeruginosa and Pcc, offering a sustainable strategy to mitigate spoilage and enhance food safety.