FIGURE 3.

Role of the P. aeruginosa carB gene during competition with S. aureus. (A) Spots of P. aeruginosa cultures were deposited on LB agar plates seeded with a lawn of S. aureus strain COL. (B) Rhamnolipid production by the wild-type PA14 and the carB-disrupted PA14 strains. No difference was observed between the two strains within duplicates indicating that the Rhl quorum-sensing (QS) is not affected in the mutant. (C) Elastase production by the wild-type PA14 and the carB-disrupted PA14. Error bars indicate standard deviations calculated from three experimental replicates. (D) Quantification of PQS production during competition with S. aureus. The carB mutant and the wild-type PA14 strains were both incubated with the competitor and with the PAO1 Δ pqsA pqsA::lux reporter strain. PQS production was evaluated by quantification of the luminescence produced by the reporter strain in response to the amount of PQS in the medium. Luminescence was quantified after 6 h of incubation at 37°C. Error bars are standard deviations calculated on duplicate.