Binding and mutagenicity studies with 2-nitrosofluorene on Salmonella typhimurium TA98 grown at different temperatures.

The growth temperature of the histidine auxotroph Salmonella typhimurium TA98 influences the extent of binding of 2-nitrosofluorene (NOF) to this bacterium as well as the mutagenicity of this chemical carcinogen. Gas-liquid chromatography (GLC) of bacteria grown at 37, 27 and 17 degrees C revealed that the unsaturated (hexadecenoic plus octadecenoic) fatty-acid content increased from 15.0% at 37 degrees C to 20.5% at 27 degrees C and to 22.2% at 17 degrees C. It has been shown using both artificial and natural mammalian membranes that NOF adds to carbon-carbon double bonds in unsaturated fatty acids via an "Alder-ene" type reaction to produce a nitroxyl free radical adduct (N-O-LAF). The same adduct was formed when NOF was incubated with Salmonella typhimurium TA98. There was an increase in N-O-LAF formed in bacteria grown at 27 degrees C as compared to those grown at 37 degrees C, but very little formed in bacteria grown at 17 degrees C. Therefore the amount of N-O-LAF formed did not correlate with unsaturated fatty-acid content. 14C-labeled NOF uptake in bacteria grown at different temperatures showed a good correlation with mutagenicity data.