FIG 1.

(A and B) Culture densities attained by populations of strain W3110 serially diluted and exposed to increasing CCCP concentrations. Microplate 200-µl populations were diluted in LBK medium containing 100 mM Na-PIPES, pH 6.5 (A), and 100 mM TAPS, pH 8.0 (B). (C) Mean endpoints at t = 16 h for evolving populations cultured with 80 µM CCCP at pH 6.5 (light bars) and with 100 µM CCCP at pH 8.0 (dark bars). At pH 6.5 and 80 µM CCCP, 8 samples were excluded from the generation 10 OD₆₀₀ data because no growth occurred. Tukey’s test gave a P value of <0.05 for growth of generations 300, 600, and 1000 compared to growth of generation 7 at both pH 6.5 with 80 µM CCCP and pH 8.0 with 100 µM CCCP.