Studies on the Permeability Change Produced in Coliform Bacteria by Ethylenediaminetetraacetate

Ethylenediaminetetraacetate added to washed cells in tris (hydroxymethyl) aminomethane buffer increases the surface permeability of all coliforms tested, including nine strains of Escherichia coli, one strain of Aerobacter aerogenes, and four species of Salmonella. Although this treatment increases passive permeability, two transport systems tested were unaffected. The permeability change is complete within 15 sec after EDTA addition at both 4° and 37°. Mg++ and metals of greater affinity than Mg++ for EDTA prevent the permeability change; Na+ and K+ do not. Those ions that prevent EDTA action cannot immediately reverse it. As treated cells metabolize, they repair their permeability barrier, restoring it completely in a period equivalent to two-thirds of a doubling time. Tests of the conditions necessary to permit repair suggest that repair requires energy metabolism but does not require protein synthesis, RNA synthesis, or surface mucopeptide synthesis. The results support the hypothesis that EDTA causes the permeability change by binding a metal, probably Mg++, and that the cell surface then undergoes a steric or chemical change that requires energy metabolism for its reversal.