FIG 4.
Results from pairwise competition experiments in LB medium. The indicated Rifr rpoB strains were competed against the appropriate congenic wild-type strain. The strains used were WN1261 (w.t.), WN1658 (A478D), WN1663 [A478D+I528V, evolved from the culture used in the experiment whose results are shown in Fig. 3D; displayed in the figure as A478D,I528V(E)], and WN1662 [A478D+I528V, reconstructed in a wild-type strain by transformation; displayed in the figure as A478D,I528V(R)]. The selection coefficients (S) (54) shown are the average values ± standard deviations from 3 independent experiments. **, P < 0.01; ***, P < 0.001 (ordinary one-way ANOVA with Tukey’s HSD test for multiple comparisons).