Genetic and Pathogenic Properties of Colicin v Plasmids in Invasive Strains of Escherichia Coli
Colicin V plasmids resident in strains of Escherichia coli are known to carry cistrons that augment the virulence of the host bacterium. Two assays were designed with which isogenic laboratory strains of E. coli K-12 with and without ColV plasmids were compared for their ability to adhere in vitro to mouse intestinal epithelium. In both assays, disks of intestinal tissue were exposed to bacteria. In the first, disks were homogenized and the numbers of viable bacteria adherent to them were estimated from colony counts of plates inoculated with dilutions of the homogenates. In the second, bacteria were labeled with {('14)C}aspartic acid; the number of adherent cells per disk was estimated by liquid scintillation spectrometry. In both assays, strains bearing the ColV plasmid adhered in two- to threefold-greater numbers than isogenic strains without the plasmid. A non-colicinogenic strain free of the ColV plasmid was selected by treatment of a ColV strain with sodium dodecyl sulfate. In the radioisotopic assay, the ColV strain associated with the epithelium in significantly greater numbers than the cured derivative. A ColV strain was created by conjugation; in the radioisotopic assay this strain bound to epithelium in significantly greater numbers than the recipient strain without the plasmid.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign