Extracellular Metabolites of Streptomycin Mutants of Escherichia Coli

Abstract

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 streptomycinsensitive 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.

Regulation of acetohydroxy acid synthase in streptomycin-dependent Escherichia coli

“…Limitation of SM has been shown to cause > m d K-12 repression of catabolite-sensitive enzymes in SM-dependent E. coli B, but not of cataboliteinsensitive enzymes such as glucose-6-phos-'. 2 phate dehydrogenase (4), and this was reafw.t. K-12 firmed in our experiments with SM-dependent E. coli K-12.…”

“…coli, when growing on glucose-salts medium containing a nonlimiting concentration of antibiotic (SM or dihydrostreptomycin [DSM]), excrete valine into the culture medium (2,10).…”

EFFECT OF DIHYDROSTREPTOMYCIN ON TETRAZOLIUM DYE REDUCTION IN ESCHERICHIA COLI

“…Magnesium, putrescine, and spermidine antagonized the action of dihydrostreptomycin in the succinate-TTC reductase system. The observation (Bragg and Polglase, 1962) that pyruvate, and certain amino acids derived from pyruvate, were formed after addition of dihydrostreptomycin to antibiotic-sensitive Escherichia coli growing exponentially on glucosesalts medium provided new evidence in support of the hypothesis that the antibiotic affects terminal respiration (Umbreit, 1949).…”

INHIBITION OF OXIDATIVE PHOSPHORYLATION IN ESCHERICHIA COLI BY DIHYDROSTREPTOMYCIN

“…On the other hand, there was no stimulation by the antibiotic of oxidative phosphorylation in preparations from streptomycin-dependent E. coli. The observations (Bragg and Polglase, 1962) on extracellular metabolites of streptomycin-dependent E. coli have shown that this mutant uses other pathways in the metabolism of glucose. It is conceivable, then, that the dependent organism has alternate pathways for energy metabolism.…”

“…The E. coli cultures used in this study, and the method of culture, were described previously (Bragg and Polglase, 1962). SB refers to a streptomycin-sensitive E. coli, RB to a resistant mutant, and DA to a dependent strain.…”