Genetic and Pathogenic Properties of Colicin v Plasmids in Invasive Strains of Escherichia Coli
Clancy, Joanna
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https://hdl.handle.net/2142/71161
Description
Title
Genetic and Pathogenic Properties of Colicin v Plasmids in Invasive Strains of Escherichia Coli
Author(s)
Clancy, Joanna
Issue Date
1983
Department of Study
Microbiology
Discipline
Microbiology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Microbiology
Abstract
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.
Three Colicin V plasmids, pH247ColV, pF54ColV, and pF70ColV, were non-conjugative in their native states. Moreover, their host strains were not lysed by male-specific bacteriophage of several classes. Spontaneous mutants of these plasmids were isolated that made their hosts sensitive to the F-specific phages R17, MS2, and fd. These derepressed (drd) plasmids and the wild-type elements from which they were derived were mutagenized with Tn5; the transposition mutants were used to estimate the ability of the host strains to donate genes on the drd plasmids to suitable recipients. The efficiencies of conjugation of such matings were comparable to those in which isogenic E. coli strains carrying F:Tn5 or RP4 were used as donors. Each of the original plasmids inhibited the fertility of F when both were present in a bacterial strain. Each, therefore, could be classified as Fi('+)(F). Their compatibility properties were determined with plasmids of Inc FI, FII, FIII, FIV, I(,1), I(,2), P, and W. Each of them was classified as Inc FIV. These plasmids, like other pColVs extant, share homology with F.
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