Effects of growth conditions on virulence gene transcriptions.

<p><i>V. cholerae toxT</i>::<i>lacZ</i> (A and B), <i>ctx</i>::<i>phoA</i> (C) and <i>tcpA::phoA</i> (D) transcription in different growth conditions were measured. Bacteria were inoculated into LB (pH 6.5) and shaken at 30°C for 6 hrs (A and B) or 16 hrs (C and D). Malonate was added to LB (pH 6.5) as indicated (A) or at 40 mM (C and D). NaCl was added to LB (pH 6.5) as indicated (B). Autoagglutination of the <i>V. cholerae</i> O395N1 cells was evaluated visually after 16–24 hrs of incubation (“+” means autoagglutination, “−” means no autoagglutination) (D). All experiments were repeated more than three times. The error bars indicate standard deviations. P values were calculated by one-way ANOVA followed by post hoc Tukey test (A and B), or Student’s t test (C and D).