Figure 3. Expression kinetics of the katN-lacZ transcriptional fusion in S. Typhimurium strains harbouring different rpoS alleles.

Growth (dashed lines) and β-galactosidase activities (solid lines) of the S. Typhimurium strains indicated, harbouring wild-type and mutant rpoS alleles from P. aeruginosa (a) and S. Typhimurium (b). Aliquots were taken at different time intervals during growth and β-galactosidase activity was measured in Miller units. Aliquots were also used for σ^S immunodetection (Supplementary Fig. S3b). The growth phase was determined by the measurement of culture turbidity at OD 600 nm. The experiments were repeated twice with similar results.