The StkP/ComE pathway controls oxidative stress and cell wall biosynthesis.

<p><b>(</b>A) The H₂O₂ production is altered in the <i>comE</i> and <i>stkP</i> mutants. Cells were grown in BHI at 37°C to an OD_620nm of 0.3, then diluted in either ABM (pH 6.0) and incubated at 37°C to an OD_620nm of 0.3. The H₂O₂ concentration was determined by the peroxidase test as described in Material & Methods. Values were calculated as the H₂O₂ concentration in mM and normalized against the number of viable cells. (B) The <i>comE and stkP</i> mutants were more susceptible to H₂O₂ than <i>wt</i>. Susceptibility to H₂O₂ is indicated as a percentage of bacterial survival at different time points. C-D) The <i>comE</i>^<i>T128A</i> mutant was more resistant to cell-wall antibiotic-induced lysis than <i>wt</i>. Cells were grown in BHI/pH 7.2 at 37°C to an OD_620nm of 0.3, and fosfomycin (C) and vancomycin (D) were added in independent cultures at final concentrations of 50 μg/ml and 0.4 μg/ml, respectively. Cell lysis of bacterial cultures was determined by turbidimetry at OD_620nm for more than 3 h. References: *** p < 0.001.