FIG. 3.

Growth and clp gene expression after heat shock. (A to D) Cultures of the WT (1), PBM001 (2), MB290 (3), or MB288 (4) were grown to the exponential phase in TSB at 37°C. At an OD₆₀₀ of 0.25 to 0.30, cultures were diluted 10⁻¹, 10⁻², 10⁻³, and 10⁻⁴-fold, and 10 μl of each dilution (top to bottom, respectively) was spotted on TSA plates. The plates were then incubated at 37°C (A), 44°C (B), 46°C (C), and 47°C (D) for 24 h. (E) Real-time RT-PCR quantification of clp gene expression after heat shock at 55°C for 15 min. clpC, clpP, and clpB mRNA concentrations in the WT (DSM 20231) and the clpC mutant (PBM001) after heat shock at 0 (□), 5 (▨), and 30 (▪) min were determined as described in Materials and Methods. Shown are transcript quantities relative to the control (gyrB) transcript, expressed as fold increase. Data are means ± standard deviations of triplicate determinations.