Extracellular metabolites of streptomycin mutants of Escherichia coli.

Bragg, P. D. (University of British Columbia, Vancouver, Canada) and W. J. Polglase. Extracellular metabolites of streptomycin mutants of Escherichia coli. J. Bacteriol. 84:370-374. 1962.-A comparison of the extracellular products of glucose metabolism during aerobic exponential growth of Escherichia coli showed that a streptomycin-dependent strain produced large amounts of l-valine while only trace amounts of this amino acid were produced by streptomycin-sensitive strains. A further difference between sensitive and dependent mutants was the production by the latter of lactic acid when the gas phase was changed from air to nitrogen. Resistant cultures grown in antibiotic-free medium were similar to sensitive cultures, but when dihydrostreptomycin was added, the resistant organism produced lactic and pyruvic acids. Three strains of streptomycin-sensitive E. coli accumulated pyruvic acid from glucose oxidation in the presence of concentrations of dihydrostreptomycin which inhibited multiplication. Further evidence is thus provided to implicate reactions of pyruvate as being of significance in the mechanism of action of streptomycin.