Figure 1: Monitoring induction of the RpoS regulon using the pada::lacZ reporter fusion.

Induction was visualized as blue rings using a disk diffusion assay on LB plates supplemented with X-gal (a) and by quantifying β-galactosidase activity in liquid LB medium (b,c). (b) Wild-type (wt), Δada and ΔrpoS strains grown in LB and LB supplemented with 1 μg ml−1 of ampicillin (Amp) (LB Amp). For each genotype, the fold increase relative to the wt level for each experimental condition is presented. (c) wt, wt strain overexpressing the ClpP–ClpX complex and the ΔrpoS strain grown in LB supplemented with 1 μg ml−1 of ampicillin. For each genotype, the fold increase relative to the untreated control is presented. For all measures, each point represents the mean±s.e.m. of three independent experiments.