TABLE 2.

Catalase activities of the wild type and ΔrpoS mutant KPR101 in various growth phases

OD600Catalase sp actaRatio (wild type/KPR101)
Wild typeKPR101
0.12.25 ± 0.191.33 ± 0.121.7
0.30.86 ± 0.100.51 ± 0.101.7
0.60.71 ± 0.070.41 ± 0.051.7
1.30.60 ± 0.140.32 ± 0.051.9
2.20.98 ± 0.060.68 ± 0.191.4
3.22.85 ± 0.072.43 ± 0.051.2
3.97.60 ± 0.073.56 ± 0.702.1
4.26.39 ± 0.552.60 ± 0.702.4
  • a Wild-type and KPR101 cells grown in LBS broth were harvested at different cell densities, and the crude extracts were processed in order to estimate the rates of H2O2 degradation by a spectrophotometric assay, as described in Materials and Methods. The concentrations of H2O2 were determined by using an extinction coefficient of 43.6 mM (3). The catalase specific activities were obtained from two independent experiments and were calculated by using the following equation (42): (1,000 × average ΔOD240/min)/[(43.6 × milligrams of enzyme)/milliliters of reaction mixture].