Enhanced bactericidal activity of platelet beta -lysin for E. coli in the presence of membrane perturbation

Under the appropriate in vitro test conditions, intact E. coli strain K-12 was shown to be susceptible to the effects of platelet-derived beta -lysin preparations. Enhanced beta -lysin activity induced by variations in the initial log phase growth temperatures of E. coli is presumed to be due to alterations in outer membrane fluidity. Treatment of E. coli with ethylenediaminetetraacetate (EDTA) or ethyleneglycoltetraacetate (EGTA) appeared to promote enhanced outer membrane permeability, which was reflected by an increase in the susceptibility of EDTA- and EGTA-treated cells to platelet beta -lysin. Restoration of outer membrane integrity was apparent when EDTA- or EGTA-treated cells were incubated in the presence of either CaCl sub(2) or MgCL sub(2) prior to beta -lysin treatment and subsequently showed resistance to beta -lysin bactericidal activity.