FIG 3.

Relative expression of quorum-sensing genes (rhlR, rhlI, lasR, lasI, rhlA, lasB) measured by quantitative reverse transcriptase PCR from P. aeruginosa biofilms untreated (control) or treated with C₄-HSL (4 μg/ml) or C11 (4 μg/ml). Biofilms were grown at 37°C for 48 h under aerobic or anaerobic conditions. The levels of QS gene expression were normalized to the level of rpoD gene expression and then compared with the level of expression by control biofilms. Results are expressed as the means and standard deviations from triplicate experiments. Statistically significant differences (**, P < 0.01; ***, P < 0.001) between the test compound and its control are indicated (n = 3).