Figure 3.

Impaired stress tolerance of the L. pneumophila LpΔclpP mutant during stationary phase. Overnight cultures of different strains were inoculated into fresh medium and grew to stationary phase (OD₆₀₀ from 3.5 to 4.5), and the cells were then treated with (A) 1 mM H₂O₂ for 30 minutes. * p < 0.05, (B) pH 4.0 citric acid for 30 minutes. * p < 0.01, (C) 57°C heat shock for 20 minutes. * p < 0.05, or (D) 0.3 M KCl for 1 hour. * p < 0.05. The experiments were carried out in triplicate.