Tetracycline-resistance inEscherichia coli; a genetic contribution |
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Authors: | W P M Hoekstra Elly M Zuidweg J B A Kipp |
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Institution: | (1) Laboratory for Microbiology, State University of Utrecht, Catharijnesingel 59, Utrecht, the Netherlands |
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Abstract: | A non-transmissible tetracycline-resistance plasmid inE. coli was found to be transmissible by transduction and by conjugation with the aid of theE. coli K12 sex-factor.
Transfer of the tetracycline-resistance plasmid (R-tet) by transduction or conjugation to anE. coli K12 Hfr strain revealed that the plasmid was incompatible with the integrated F-factor. Selection for tetracycline-resistance
after conjugation or transduction yielded Hfr colonies which carried the tetracycline-resistance determinant as a chromosomal
marker. The tetracycline-resistance determinant was integrated at the 1 min region of theE. coli chromosome map (Taylor and Trotter, 1967) between the markersara andleu.
Apart from Hfr colonies with a chromosomal tetracycline-resistance determinant, F-gal+-mediated transfer of R-tet to strain Hfr R4 gave some colonies in which the tetracycline-resistance determinant was carried on a fused plasmid that,
besides the resistance determinant, contained thegal
+ marker of the original F-gal
+. This fused plasmid is transmissible and confers to an F− cell male-specific phage-sensitivity, like an F-factor does. It is suggested that this fused plasmid, which is compatible
with the integrated F-factor in the Hfr R4 cells, arose by recombination between F-gal
+ and R-tet. |
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