Fig. 2: comK induction occurs in fermenting S. aureus strains.
From: The induction of natural competence adapts staphylococcal metabolism to infection
A Fluorescence microscopy analysis of PcomG-yfp expression in the WT and the nitrosoguanidine-treated strain NG8. The NG8 strain showed a heterogeneously distributed fluorescence signal in a subpopulation of cells. Scale bar = 10 μm. B Quantitative determination of the fluorescence signal in PcomG-yfp-expressing WT and NG8 strains. The negative and positive controls were B. subtilis 168 WT and the PcomG-yfp labeled strain, respectively. Significance was measured by two-tailed Student t test; ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). C qRT-PCR analysis of comK expression in untreated TSB cultures. Statistical analysis, two-tailed Student t test; **p < 0.01. Data are shown as mean ± SD of three independent experiments (n = 3). D Growth curves of WT and NG8 strains in untreated TSB cultures. Two-tailed Student t test. Data are shown as mean ± SD of three independent experiments (n = 3). E Classification of ORFs that harbor SNPs in the strain NG8 using TIGRfam, SEED, and Gene Ontology functional categories. Represented ORFs harboring nonsense mutations and missense mutations with moderate effect. For each category, columns represent the number of regulated genes. Group 1—protein metabolism; group 2—carbohydrate metabolism and respiration; group 3—amino acid metabolism; group 4—stress response genes; group 5—virulence; group 6—iron acquisition; group 7—DNA metabolism (gray), cell division (white); group 8—other genes. Group 2 genes were more strongly represented in the NG8 strain (highlighted in blue). F Determination of acetate (i) and lactate (ii) levels in culture supernatants of the WT and NG8 strains. To measure acetate production, 10 ml of TSB cultures were grown in 100 ml Erlenmeyer flasks. To measure lactate production, 20 ml of cultures were grown in 100 ml Erlenmeyer flasks. Concentration is represented in relation to culture OD600. Statistical analysis, two-tailed Student t test. Data are shown as mean ± SD of three independent experiments (n = 3). G Determination of oxygen consumption rate in WT and NG8 strains over time. Oxygen quenches the fluorescence signal of the dye (ab197243) added to the culture, thus oxygen consumption is directly related to fluorescence. Oxygen consumption rates are represented as relative fluorescence units in relation to cultures at OD600. Cultures were grown in TSB medium for 24 h at 37 °C with agitation (200 rpm). Two-tailed Student t test. Data are shown as mean ± SD of three independent experiments (n = 3). H. qRT-PCR analysis of comK expression in TSB cultures of small-colony variants (SCV). SCV1 and SCV2 are clinical isolates from the Hospital Ramón y Cajal (Madrid, Spain). ΔhemB is a laboratory mutant. Comparisons were made using one-sided ANOVA with Tukey’s test for multiple comparisons; **p < 0.01. Data are shown as mean ± SD of three independent experiments (n = 3). Source data are provided as a Source Data file.
