Mutagen screening with bacteria: niridazole and nitrofurans.

The mutagenic activity of nitrofuran derivatives and of niridazole is easily demonstrated by spot tests using E. coli WP2 and its uvrA derivative but not by spot tests using the S. typhimurium strains developed by Ames. Quantitative tests show that S. typhimurium TA 1538(but not TA 1535, -36 or -37) is weakly induced to revert by niridazole. However, the maximum yield of revertants is well below that obtained with E. coli WP2 uvrA. None of the S. typhimurium strains respond to the three nitrofurans tested even in quantitative tests. The S. typhimurium strains contain the reductase required for metabolic activation of the nitrofurans and treatment of a uvr+ S. typhimurium strain with niridazole or with nitrofurazone causes single-strand breaks in DNA.