FIG 1.

Indole is produced at stationary phase and inhibits virulence factor production. (A) WT strain JB58 and an isogenic ΔtnaA mutant were cultured in LB medium at 37°C with shaking. Culture aliquots were collected at the indicated times; cell growth was assessed (right axis, triangle symbols), and indole production was quantified (left axis, circle symbols). The presented data show the means ± the standard deviations (SD) for at least three independent experiments. (B) V. cholerae strain JB58 was grown under AKI conditions with the indicated amounts of indole before CT and TcpA production (inset) were assayed. The CT data are the means ± the SD of three independent experiments. Statistical significance was determined using one-way analysis of variance (ANOVA) comparing each mean to that of the methanol control (*, P < 0.05).