Basal expression rate (Pa) of P<i>_liaI</i> at 1 and 0.3 µg/ml bacitracin.

<p>The average fluorescence intensities (FI_basal) of cells in the ‘OFF’ state increased with time, saturating shortly thereafter. This enabled us to determine the basal expression rate (Pa) as described in the Material and Methods section. The maximal basal fluorescence intensity decreased with lower bacitracin concentrations. Similarly, the basal expression rate was significantly reduced in experiments with 0.3 µg/ml bacitracin as compared to 1 µg/ml bacitracin. A) and C) Fluorescence development of cells being in the ‘OFF’ state (FI_basal). Solid line: best fit to a sigmoid function (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053457#pone.0053457.s006" target="_blank">Table S6</a>). B) and D) Expression rate of P<i>_liaI</i> as the first derivative of fluorescence development given in A) and C). Solid line: best fit to a Gaussian function (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053457#pone.0053457.s007" target="_blank">Table S7</a>). A) and B): 1 µg/ml bacitracin, C) and D) 0.3 µg/ml bacitracin. E) and F) comparison of switching rate P_fON (grey) and basal expression rate Pa (black). E) 1 µg/ml bacitracin. F) 0.3 µg/ml bacitracin.