Transcription of chromosomal rpoS::lacZ in P. aeruginosa PAO1 (▵), the LasR− mutant PAO-R1 (□), the RhlR− mutant PDO111 (▿), the LasI− RhlI− double mutant PAO-MW1 (○), and PAO-MW1 in medium containing 3OC12-HSL (2 μM) and C4-HSL (5 μM) (◊). Five rpoS-lacZ transconjugants were analyzed, and the results were indistinguishable from those shown.