0025 OD600 over two independent experiments. NEG is not a reporter fusion strain, so there is no Selleckchem 4SC-202 GFP expression. D) No rhamnose is detectable in NEG in two independent experiments (black and gray). E) Rhamnose is undetectable in QSN in the absence of C4-HSL in two independent experiments (black and gray squares), but is reconstituted in the presence of C4-HSL (black and gray triangles). F) Rhamnose secretion in IND in two independent experiments (black and gray squares). The inset

shows the complete range of rhamnose secretion in IND cells under our experimental settings. HM781-36B research buy Figure 5 Determination of the reproducibility of the lag phase in NEG, QSN and IND. For NEG, τ shows a correlation to ln (X2/X1) with an R2 of 0.998 (p < 0.0001) and a μ max of 0.28 ± 0.01 h-1. The median and range over two independent experiments are plotted

as squares and error bars. For QSN in the absence of autoinducer, τ shows a correlation to ln (X2/X1) with an R2 of 0.998 (p < 0.0001) and a μ max of 0.27 ± 0.01 h-1. In the presence of C4-HSL τ shows a correlation to ln (X2/X1) with an R2 of 0.994 (p < 0.0001) and a μ max of 0.22 ± 0.02 h-1. The median and range over two independent experiments are plotted as black squares (without autoinducer) or gray triangles (with autoinducer) selleckchem with their respective error bars. For IND, τ shows a correlation to ln (X2/X1) with an R2 of 0.997 (p < 0.0001) and a μ max of 0.27 ± 0.01 h-1. The median and range over two independent experiments are plotted as squares and error bars. We then used the same method for a signal-negative mutant, QSN, both in the absence and in the presence of autoinducer (C4-HSL) supplied in the media. Again, the growth curves aligned well for both conditions (Figure 5B; R2 = 0.998 and R2 = 0.994, respectively). As expected, the cells did not secrete rhamnolipids in the absence Depsipeptide datasheet of C4-HSL (Figure 4E, gray and black squares), but the addition of 5 μM C4-HSL to the media restituted rhamnolipid production (Figure 4E, gray and black triangles). Importantly, although the amount of

gene expression and rhamnolipid secretion in the presence of C4-HSL was lower than for WT both at the population- (Figure 2) and individual cell-level (as assessed by GFP divided by OD, data not shown), the timing remained the same (Figure 4B). This is consistent with previous observations that the time delay of the quorum sensing-controlled rhlAB operon in signal-positive P. aeruginosa is maintained even when the medium is complemented with high concentrations of autoinducers [13, 25]. We then carried out experiments with an inducible strain (IND), which expresses rhlAB constitutively upon induction with L-arabinose. The purpose of this experiment was to provide a positive control showing that the only requirement for rhamnolipid secretion is the expression of rhlAB [24]. The growth curves for this strain also aligned well (R2 = 0.997, Figure 5C). When IND was grown with 0.