[Nitrous acid induction of Escherichia coli mutants pathogenic for poultry]

Three strains of Escherichia coli - 0 78:K 80, 0 2:K 1, and 0 111: K 58, the first two pathogenic for birds - were used to test the mutagenic action of nitrous acid. Survival curves were drawn, and the optimal conditions were determined for the action of nitrous acid as a mutagenic factor. A scheme was suggested for the isolation of streptomycin-resistant and streptomycin-dependent mutants. The capacity of nitrous acid to induce mutations was demonstrated with regard to the streptomycin-dependence phenomenon and the rough (R) form of colonies. Discussed is the optimization of the streptomycin concentrations needed for the growth of the streptomycin-dependent mutants. Tested have been some biochemical activities of the mutants in comparison with the initial forms. It has likewise been demonstrated that the streptomycin-dependent mutants in R form change their reaction to some carbohydrate sources, either assimilating them at a delayed rate (as in most cases) or losing the capacity to assimilate them.