The action of streptomycin. VI. A new metabolic intermediate

ACTION OF DIHYDROSTREPTOMYCIN AND ANTAGONISM BY CATIONS

Bragg, P. D. (University of British Columbia, Vancouver, Canada) and W. J. Polglase. Action of dihydrostreptomycin and antagonism by cations. J. Bacteriol. 85:590-594. 1963.-A number of antibiotics including dihydrostreptomycin inhibited the induction of beta-galactosidase in Escherichia coli and, except in the case of chloramphenicol, magnesium antagonized the inhibition. Of the antibiotics tested, only dihydrostreptomycin caused formation of pyruvate from the oxidation of glucose. Under similar conditions, inhibitors of terminal respiration (cyanide, azide, amobarbital) also caused formation of pyruvate. Magnesium and the polyamines, putrescine and spermidine, were observed to antagonize dihydrostreptomycin in systems in which the antibiotic showed an inhibitory action.

ELECTRON-TRANSPORT COMPONENTS OF STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI

Bragg , P. D. (University of British Columbia, Vancouver, B. C, Canada) and W. J. Polglase . Electron-transport components of streptomycin-dependent Escherichia coli . J. Bacteriol. 86: 544–547. 1963.—When a streptomycin-dependent strain of Escherichia coli was grown in antibiotic-free medium, the resulting streptomycin-depleted cells were found to contain relatively large amounts of vitamin K 2 . Cytochromes a 1 and a 2 were absent from depleted cells, and these cells metabolized glucose with the accumulation of lactic acid. Depleted cells were normal in their content of coenzyme Q 8 , total flavine, and cytochrome b . Growth of depleted cells on medium containing dihydrostreptomycin restored their ability to metabolize lactic acid concomitantly with a decrease in vitamin K 2 to a normal level, and with the formation of cytochromes a 1 and a 2 . It is concluded that streptomycin (or dihydrostreptomycin) is required by dependent E. coli for maintenance of the integrity of the electron-transport system.