Influence of <i>hfq</i> on indole production and ornithine decarboxylase activity.

<p>(A and B) The concentration of indole present in culture supernatants was determined after growth in LB at 27°C. (A) Bacteria were grown for four hours at 27°C. Data represent mean and standard deviation of at least three independent experiments each performed with triplicate independent cultures. (B) Complementation analysis. Bacterial cultures were grown for 16 h at 27°C, since strains carrying plasmids were delayed in their indole production. Because of the variability of indole concentration produced by parental strains carrying plasmids (between 0.07 and 1.5 mM in four independent experiments), results were expressed relative to the indole produced by the parental strain JB580v carrying the control vector(which was set at 100%). Data represent mean and standard deviation of four independent experiments each performed with at least triplicate independent cultures. Significance was calculated with Student‘s unpaired <i>t</i>-test (*<i>P</i><0.05; **<i>P</i><0.01; ***<i>P</i><0.001). (C) Ornithine decarboxylase activity detected using the API-20E strip. All wells are positive (negative wells remain yellow), but wells inoculated with <i>hfq</i>-negative strains turn red, whereas those inoculated with parental strains are more orange.