The transcription and activity of virulence genes depends on L-glutamine.

<p>(A) RT-qPCR transcription analysis of <i>hly</i>, <i>plcA</i>, <i>plcB</i>, and <i>actA</i> in WT bacteria grown in MDM with either 4 mM L-glutamine (gray bars) or 4 mM NH₄Cl (black bars) as a sole nitrogen source. Transcription levels are presented as relative quantity (RQ), relative to levels in WT. Results are mean ±SD of 3 independent experiments performed in triplicates. (B) Hemolysis activity of LLO in culture supernatants of WT and <i>ΔglnPQ</i> bacteria grown on minimal defined media with 1 mM L-glutamine (grey) or 4 mM NH₄Cl (black) as the sole nitrogen source. (C) Analysis of PI-PLC activity of PlcA in culture supernatants of WT (circles) and <i>ΔglnPQ</i> (squares) bacteria grown on minimal defined media with 1 mM L-glutamine (full symbols) or 4 mM NH₄Cl (empty symbols) as the sole nitrogen source. Representative graphs of 3 biological repeats are shown. Error bars represent standard deviation of the triplicate.