Fig. 1.

Effect of LeuO on cadC and aphB expression. (a) WT V. cholerae strain JB58 and ΔleuO strain XBV222 carrying the cadC-lacZ reporter plasmid pXB239 were grown under AKI conditions. Culture aliquots were taken at the indicated times and assayed for β-galactosidase activity as described in Methods. The presented data are the mean ± sd of three independent biological replicates. (b) WT strain JB58 bearing pBAD33-leuO plasmid pVA126 and either the cadC-lacZ transcriptional reporter pXB239 (black bars) or the aphB-lacZ transcriptional reporter pXB203 (grey bars) were grown under AKI conditions in the presence or absence of 0.02 % arabinose. Expression of the indicated reporter gene was assessed at 5 h by measuring β-galactosidase production. The presented data are the mean ± sd of three technical replicates and are representative of two independent experiments. Statistical significance was determined using a t-test comparing the sample mean with the WT control mean; *P < 0.05, **P < 0.01.