Parallel between ultraviolet light and 4-nitroquinoline-1-oxide sensitivity in Bacillus subtilis.

The compound 4-nitroquinoline-1-oxide (4NQO) is known to have lethal, mutagenic, and bacteriophage-inducing properties similar to those of ultraviolet light (UV) in Escherichia coli (S. Kondo and T. Kato, Proc. 2nd Intern. Biophys. Congr., Vienna, 1966, in press). We found that this correlation holds for the lethal and, perhaps, [optical density value at 600 nm (OD600), 0.3] in nutrient broth or minimal medium (2), plus the required supplements. (Thymine-requiring strains form long filaments in nutrient broth but not in minimal broth supplemented only with the required growth factors. Nutrient agar, however, is suitable for plating purposes.) They were then