FIG. 2.
Catalase activity in B. cereus ATCC 14579 and B. cereus FM1400. Levels of catalase activity of whole cells of B. cereus ATCC 14579 (WT) and B. cereus FM1400 (−sigB) were determined. Levels of catalase activity of aerobically (+O2) grown cells in the mid-exponential growth phase in BHI (me) and after a 30-min heat shock from 30°C to 42°C (hs) were determined. Catalase activity of cells grown in anaerobic (−O2) culture was also determined. Cells were pelleted by centrifugation, washed once in PBS, and resuspended in PBS containing 40 mM H2O2. One unit of catalase activity was defined as a decrease in the absorbance at 240 nm of 1 per minute and adjusted for the OD600 of the cultures. The averages of three independent experiments are shown. The error bars indicate standard deviations.