Figure 1.

Growth curves, plating efficiency and LptE levels of the wild type strain P. aeruginosa PAO1 and the lptE conditional mutant. (a) Stationary phase PAO1 and lptE conditional mutant (lptE) cells grown in MH with 0.5% arabinose (ARA) were diluted 1:1000 in flasks containing MH with or without 0.5% ARA (first refresh). After 24 h of growth, PAO1 and lptE cells grown in the absence of ARA were sub-cultured (dilution 1:200) in flasks in fresh medium containing or not 0.5% ARA (second refresh). As the growth curves of PAO1 with or without ARA were basically superimposable, for clarity only the curve in the absence of ARA is shown. Values are the mean (±SD) of three independent experiments. Asterisks indicate the time-points at which the growth of lptE without ARA was significantly different from that of other samples (P < 0.05, Kruskal-Wallis) (b) Western blot analysis to quantify LptE levels in whole cell lysates (20 µg of proteins; neat), or serial 1:2 dilutions as indicated, from PAO1 or lptE conditional mutant cells grown for 14 h in MH with or without ARA for one or two passages (lptE 2^nd). Filters were developed with Cyanagen Westar ηC Ultra 2.0 reagent and visualized in a Odissey system (Li-Cor) system. (c) Colony growth of PAO1 and lptE on MH agar plates supplemented or not with ARA. Exponential phase cultures in MH with 0.5% ARA were normalized to OD₆₀₀ = 1 in saline, and 5 μL of the 10⁻²–10⁻⁶ dilutions were spotted onto the plates and incubated for 20 h at 37°C. Images in panels B-C are representative of at least three experiments giving similar results.