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Appl Environ Microbiol. 1968 February; 16(2): 239-241
Copyright © 1968 American Society for Microbiology. All Rights Reserved.

Effect of Metallic Cations on the Viability of Phenol-treated Escherichia coli

Pharmacy Department, Chelsea College of Science and Technology, University of London, London, England

ABSTRACT

Five metallic cations (Fe³⁺, Cr³⁺, Ca²⁺, Mg²⁺, Mn²⁺; concentration range, 1.85 x 10^-4 to 37 x 10^-4M) were incorporated individually as chlorides into nutrient broth and agar media used for the recovery of phenol-treated Escherichia coli. The effects observed varied with the concentration and the ionic species. In nutrient agar, Fe³⁺ and Cr³⁺ were generally beneficial but were toxic at 37 x 10^-4M. Of the divalent ions tested, Ca²⁺ and Mg²⁺ usually gave higher counts in nutrient broth, except at a concentration of 9.25 x 10^-4M, whereas the effect of Mn²⁺ was rather variable. Two possible explanations are suggested to explain these effects. Toxic materials may be removed from the media by the precipitates formed on the addition of Fe³⁺ or Cr³⁺, or, in the case of the divalent ions, the integrity of the bacterial cell membranes may be maintained.