Figure 2

Indole represses flagella production and motility of Salmonella . (A) The effect of indole on expression of flhC measured by qRT-PCR. The wild-type strain ATCC 14028s and its ramR::kan^R and ramA::kan^R deletion mutants were grown in the presence (+) or absence (−) of 1 mM indole. flhC expression level was expressed relative to that measured in the wild-type strain grown without indole, which was assigned the unit value. The data corresponds to mean values from three independent replicates. The bars indicate the standard deviation. (B) Transmission electron microscopy was used to detect flagella on the wild-type strain (ATCC 14028s) grown in the presence or absence of 1 mM indole. (C) The number of flagella attached to a single cell was counted from images taken using transmission electron microscopy. Data were collected from 30 bacterial cells for both indole-treated and untreated cells. Bars correspond to the standard deviation. Asterisks indicate statistically significant differences (p < 0.01) according to the two-tailed Student’s t-test. (D) Indole represses motility of Salmonella. After incubation of the wild-type ATCC 14028s strain in the presence or absence of 1 mM indole, motility was assayed on a semi-solid agar plate. Result is representative of one of the three experiments.