A novel marine derived N-Acyl homoserine acylase, PamA, inhibits virulence factors in biofilm forming Pseudomonas aeruginosa

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Pseudomonas aeruginosa is a biofilm forming, opportunistic pathogen frequently isolated from various food sources, posing a threat to both food safety and public health. Current sanitation strategies are insufficient to prevent its transmission to humans, highlighting the need for sustainable alternatives to chemical preservatives. Here we reported a novel acylase with virulence suppression effects through quorum quenching. A marine originated bacterial strain, Pararhodobacter aggregans XY-270, was found to degrade hexanoyl-L-homoserine lactone (C 6 -HSL) in vitro without bactericidal activity. Further analyses identified an N -acyl homoserine lactone (AHL) acylase (PamA), which has conserved Ser (S267) and Asn (N268) residues required for catalysis and a penicillin amidase region characteristic of the penicillin-G family, but shares low sequence identity (<33%) with known acylases. PamA can degrade C 6 -C 14 AHLs with or without an oxo-group substitution at the C-3 position. Furthermore, PamA significantly suppressed motility, biofilm formation, pyoverdine and rhamnolipid production and hemolytic activity in representative P . aeruginosa isolates. PamA treatment led to substantial disruption of biofilm architecture observed by SEM, and downregulated key quorum sensing and biofilm-related genes as evidenced by qRT-PCR. These results suggest PamA is a novel AHL acylase with broad-spectrum activity, offering food industry potential for combating biofilm-forming pathogens while minimizing resistance development.

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