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Updated: Aug 22, 2026

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
A staphylococcal plasmid that replicates and expresses ampicillin, gentamicin and amikacin resistance in Escherichia
P Gadaleta1, S Kaufman, P Martini
1Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Abstract:
Plasmid pPG1 from Staphylococcus aureus coding for ampicillin (Apr), gentamicin (Gmr) and amikacin (Akr) resistance was transformed into Escherichia coli. Transformation efficiency was about 2 x 10(3) transformants/micrograms of plasmid DNA. The plasmids present in the E. coli transformants were identical to pPG1 according to their restriction patterns. The copy number of pPG1 was estimated to be at least 20-times less in E. coli than in S. aureus. The minimal inhibitory concentrations (MICs) for Ap and Gm were lower in E. coli than in S. aureus. However, the MIC for Ak was higher in E. coli transformants than in S. aureus. pPG1 was maintained in the E. coli transformants for at least 80 generations at 37 degrees C without antibiotic selection pressure.
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