FIGURE 2.

Detection of C₄-HSL signals produced by P. aeruginosa mutant strains. (A) Analysis of the C₄-HSL signals produced by P. aeruginosa acpP2 and acpP3 mutant strains using Chromobacterium violaceum reporter strain CV026. (B) Quantitative analysis of the C₄-HSL signal produced by P. aeruginosa acpPs mutant strains using high performance liquid chromatography (HPLC). (C) Analysis of the C₄-HSL signals produced by P. aeruginosa acpP1 mutant strains using C. violaceum reporter strain CV026. The acylated HSL fraction was extracted from the supernatants of stationary-phase cultures grown in LB broth at 37°C for 12 h. PAO1, P. aeruginosa wild type strain; PA-A2, P. aeruginosa acpP2::Gm^r single mutant strain; PA-A3, P. aeruginosa acpP3::Gm^r single mutant strain; PA-A23, P. aeruginosa acp2::Tc^r acp3::Gm^r double mutant strain; PA-A1, P. aeruginosa acp1::Ec acpP single mutant strain; PA-A12, P. aeruginosa acp1::Ec acpP acp2::Gm^r double mutant strain; PA-A13, P. aeruginosa acp1::Ec acpP acp3::Gm^r double mutant strain; PA-A123, P. aeruginosa acp1::Ec acpP acp2::Tc^r acp3::Gm^r triple mutant strain; PK-Pa, P. aeruginosa acp1::Ec acpP single mutant strain carrying plasmid, pSRKPa, encoding wild type P. aeruginosa acpP1 gene. Data are the mean ± standard deviation of triplicate measurements. Pair-wise comparisons were made between wild-type strain PAO1 and each mutant strain by Student’s t-test. ^∗∗∗Highly significant difference, P < 0.01. ^∗∗Significant difference, P < 0.05. ns, no significant difference, P > 0.1.