The toxicity and mutagenicity of n‐nitroso compounds in sarcina lutea and salmonella typhimurium

Mutants of Salmonella typhimurium have been used as tester strain in assessing the mutagenicity of various compounds. The revertants arising from the backmutation of these mutants by tested chemicals were counted and used as the measure of mutagenicity. Several N‐nitroso compounds were found to be insensitive to Salmonella system. In searching for a new microbial system for evaluating the toxicity and mutagenicity of N‐nitroso compounds, we found that the Grampositive coccoid organism Sarcina lutea is responsive to the challenge of these compounds. The wild type of Sarcina lutea is characterized by its gold yellow colony. On treating with direct‐reacting N‐nitroso compounds, Sarcina lutea produces several groups of mutants with different color of colonies such as white, pink and pale‐yellow. It seems that the mutants result from the induced mutation of the genes responsible for the synthesis of carotenoids. Several newly synthesized N‐nitroso compounds including N‐nitrosophenacetin, 2‐nitro‐N‐nitrosophenacetin, N,N′‐dimethyl‐N‐nitrosourea and nitrosated 2‐carboline derivatives were tested on this newly developed system. For the purpose of comparison, the mutagenicity of these compounds were also tested on several Salmonella typhimurium strains such as TA 97, TA 98, TA 100, TA 1538, TA 1537, and TA 1535.