FIG 5.

Effect of leuO on the expression of the V. cholerae RND efflux systems. V. cholerae WT strain JB58 and ΔleuO mutant strain XBV222 carrying lacZ promoter fusion reporter plasmids for vexRAB-lacZ (pXB233) (A), vexCD-lacZ (pXB231) (B), vexEF-lacZ (pXB228) (C), vexGH-lacZ (pXB229) (D), vexIJK-lacZ (pXB230) (E), or vexLM-lacZ (pXB232) (F). All strains were cultured in LB in the presence or absence of 0.2% bile before being assayed for β-galactosidase activity, as described in Materials and Methods. The presented data are the means ± SD of the results from three independent experiments.