Figure 7. QSIs modulated activity of the AHL-sensors in P. aeruginosa.

Luminescence of the reporting operon lux, expressed in relative light units (RLU/OD₆₀₀), was measured in E. coli bioindicator strains harboring the LasR (A) and RhlR (B) AHL-sensing systems of P. aeruginosa in the presence of C4-HSL and OC12-HSL, respectively. The QSIs estradiol, estrone, estriol and hordenine were added at 0.1 mg/ml, while naringenin and naringin, added at 0.5 mg/ml, were used as QSI-reference and non-QSI reference, respectively. Each test (n = 6) was compared with the DMSO-condition using Student's t test. Asterisks indicate statistically different data (p value of ≤0.01).