Figure 1. Dose-dependent inhibition of AHL-mediated QS by BF8.

The structure of BF8 (A) and relative QS activities of V. harveyi BB886 (B) and PAO1 lasB reporter (C) are shown. To study the effects on QS in V. harveyi BB886 reporter, an overnight culture of V. harveyi BB886 were diluted 1∶5000 in AB medium and supplemented with different concentrations of BF8 after 5.5 h of incubation. The QS activity of each sample was characterized by normalizing the bioluminescence of the reporter V. harveyi BB886 with its colony forming unit (CFU) after another 1.5 h of incubation. Figure 1B shows that QS was inhibited by BF8 in a dose dependent manner. To study the effects on QS in PAO1, the reporter strain PAO1 mini-Tn5-based PlasB-gfp(ASV) was cultured till an OD₆₀₀ of 0.8 was reached and then BF8 was added at different concentrations. The green flouresence was measured when the cultures reached stationary phase (OD₆₀₀ around 2.7). The results show that QS in PAO1 was inhibited by BF8.