FIG 2.

Isolates from early generations (900 to 1,400 doublings) from populations A1, A5, C3, and G5. Strains were cultured in LBK buffered with 100 mM PIPES, pH 6.5, and 20 mM sodium benzoate, as described in Materials and Methods. For each strain, the curve shown represents the median value of the OD₆₀₀ at 16 h. *, significant difference from W3110, as determined by Tukey’s test (P ≤ 0.05; n = 4). The results for all four replicates are shown in Fig. S1 in the supplemental material. (A) A5-5, A1-5, A1-3, and A1-4 outgrew ancestor W3110. A5-3 and A5-4 entered death phase after 12 h, as did ancestor W3110. (B) C3-5, G5-3, G5-4, and G5-5 showed increased benzoate resistance compared to ancestor W3110. C3-3 and C3-4 entered death phase after 12 h, as did ancestor W3110.