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

<p>The structure of BF8 (A) and relative QS activities of <i>V. harveyi</i> BB886 (B) and PAO1 <i>lasB</i> reporter (C) are shown. To study the effects on QS in <i>V. harveyi</i> BB886 reporter, an overnight culture of <i>V. harveyi</i> 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 <i>V. harveyi</i> BB886 with its colony forming unit (CFU) after another 1.5 h of incubation. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045778#pone-0045778-g001" target="_blank">Figure 1B</a> 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 P<i>lasB</i>-<i>gfp</i>(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.