Sensitivity of repair-deficient mutants and similar mutants to 4-nitroquinoline 1-oxide, 4-nitropyridine 1-oxide, and their derivatives.

also tested. 4-Nitroquinoline 1-oxide, 4-hydroxyaminoquinoline 1oxide, 3-methyl-4-nitropyridine 1-oxide, and 2,3-dimethyl-4nitropyridine 1-oxide caused wider growth-inhibiting zones with mutants of Escherichia coli, such as the DNA polymerase 1-deficient mutant, po/Al, and the recombination-deficient mutants, r<?cA13 and recB21, than with the wild strain. These compounds also caused wider growth-inhibiting zones with ultraviolet-sensitive mutants of Saccharomyces cerevisiae and Bacillus subtilis than with the corresponding wild types. 4-Nitropyridine 1-oxide, /V-methyl-./V'-nitro-A'-nitrosoguani-