Production and properties of an inhibitor of the Pseudomonas autoinducer by Pseudomonas aeruginosa

An inhibitor was found in the culture fluid of Pseudomonas aeruginosa PAO1. which could inhibit the activity of the Pseudomonas autoinducer (PAI). The maximal inhibitory activity occurred in stationary phase culture supernatant. The PAI inhibitor did not influence the cell growth and the PAI production by P aeruginosa PAO1 when the PAI inhibitor was added into culture medium. The induced expression of lacZ in the reporter strain Agrobacterium tumefaciens NT1 was suppressed by this PAI inhibitor, whereas inhibition could be relieved by increasing the autoinducer concentration. The quorum sensing of P. aeruginoso was inhibited presumably by inhibiting the inducing activity of Pseudomonas autoinducer but not by inhibiting the production of Pseudonionas autoinducer. It was demonstrated that the structure of the PAI inhibitor was different from that of acyl-hornoserine lactones