Effect of Some Metabolites and Antimetabolites on the Breakdown of Deoxyribonucleic Acid and on the Colony-Forming Ability of Escherichia coli B after Gamma Irradiation: I. Effect of Citrate, Glutamate, Succinate, Versene and Magnesium Ions

Abstract

The effect of a series of metabolites related to the tricarboxylic acid cycle, also of the chelating agent FDTA, and of Mg2+ ions, on the gamma - irradiation-induced breakdown of DNA and viability of E. coli B was studied. High concentrations of citrate, succinate, and glutamate added to acetate buffer in which the cells have been incubated after irradiation inhibit both the biosynthesis of DNA in the controls and its breakdown in the irradiated cells. These substances have, however, a rather unfavorable action on the colony-forming ability of both the unirradiated and irradiated bacteria, causing their decrease, or even complete suppression. Lower concentrations of succinate and glutamate (10-3 M), and the same concentration of EDTA, only partially inhibit the breakdown of DNA in the irradiated cells. The possible meanings of the above results are discussed.