Nitrosamine formation by clinical isolates of enteric bacteria

Abstract Bacteria isolated from the normal and the hypoacidic stomach were investigated for their ability to catalyse the nitrosation of the secondary amine morpholine. Bacterial numbers were found to be dependent upon pH and species characteristic of the faecal flora were found only in the hypoacidic group. A range of nitrosating abilities was found. The inclusion of 5 mM nitrite during growth produced strain-specific results, in some cases stimulating the catalysis, in others providing inhibition. It is proposed thar catalysis may involve a nitrite reductase and that the different effects of nitrite on nitrosation may be due to contributions from two or more types of reductase activity.