Fig 2.

Deletion of pspA increased the persister ratio under various antibiotic treatments. The wild type and ∆pspA from the middle stationary phase were diluted at a ratio of 1:20 in fresh LB medium with (A)100 µg/mL ampicillin, (B) 100 µg/mL carbenicillin, (C) 5 µg/mL meropenem, (D) 2 µg/mL ciprofloxacin, and (E) 5 µg/mL levofloxacin respectively, and incubated for 8 h at 37°C with shaking. (F) The time-kill curves of ∆pspA with pBAD (Vector) or ∆pspA with pBAD-pspA (RESC) under 5 µg/mL meropenem or 2 µg/mL ciprofloxacin for 8 h as described above. The number of viable cells was counted before and after antibiotic treatment for 2, 4, 6, and 8 h. The error bar indicates the standard deviation of at least three independent experiments. The mean survival values of wild type and ∆pspA at the same time point (except for 0 h) were compared by two-tailed Student’s t test (A to E) or one-way ANOVA with Sidak’s posttest for multiple comparison (F). *, P < 0.05; **, P < 0.01; ***, P < 0.005.