PQS signaling and temperature variation modulate phage infection in Pseudomonas aeruginosa: Implications for foodborne pathogen control.

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen that poses significant risks in food-related environments. Bacteriophages have emerged as a promising alternative strategy to control P. aeruginosa infections. Notably, quorum sensing (QS) systems play an important role in bacteria-phage interactions, but our knowledge of the role of QS remains insufficiently understood. Here, we report that the synthesis defect of quinolone signal (PQS) in P. aeruginosa significantly increased phage resistance. The regulation of PQS on phage infection is likely to be rigorous since excessive addition of PQS cannot decrease the phage resistance of pqsA mutant. No differences were found in phage adsorption between P. aeruginosa PAO1 and pqsA mutant, which is different from several previous reports that bacterial QS systems participate in phage adsorption. More importantly, we found that the phage resistance of PaΔpqsA is reversible, as higher culture temperatures can partially restore the phage sensitivity of PaΔpqsA. Our data uncover a new example of bacteria-phage interaction mediated by the pqs QS, which may help in filling some gaps in the field and provide important guidance for developing phage-based control strategies against P. aeruginosa.