Toxicity of copper and ascorbic acid to Serratia marcescens

Zimmerman, Leonard (Fort Detrick, Frederick, Md.). Toxicity of copper and ascorbic acid to Serratia marcescens. J. Bacteriol. 91:1537-1542. 1966.-Neutral solutions of ascorbic acid were antibacterial to Serratia marcescens at low but not at high population densities. The toxicity of ascorbate was eliminated by metal-sequestering treatments, and was restored only by the addition of trace amounts of copper salts. Copper-ascorbate was equally toxic under aerobic or anaerobic conditions; its toxicity was abolished by (i) chelating agents that sequestered the copper, (ii) metal-complexing agents that bound to the cells but did not sequester copper, and (iii) iron salts in the presence of air. On the basis of these observations, the toxic effects of copper-ascorbate were attributed to its reaction with vital Fe-containing cellular components.