Catalase Activity in Escherichia Coli

Witkin (1946) reported a mutant, designated Escherichia coli, strain B/r, which was more resistant to direct ultraviolet radiations than the parent strain B of E. coli. The same mutant also was found to be more resistant to X-rays, penicillin, sodium sulfathiazole (Witkin, 1947), and nitrogen mustard (Bryson, 1948). Morse and Carter (1949) found E. coli, strain B/r, to contain 3 to 4 times more desoxyribose nucleic acid than E. coli, strain B. Bryson (1949) also found the B/r strain to be more resistant to the lethal actions of substrates which had been irradiated with ultraviolet light or treated with hydrogen peroxide. However, he found no difference between the B/r and B strains in their resistance to bactericidal concentrations of hydrogen peroxide. In view of the effect catalase has on such treated substrates (Wyss et al., 1948) it was decided to compare the catalase activity of the two strains of E. coli to determine if any of the differences between the strains could be attributed to increased catalase activity.