Studies on transformation of Escherichia coli with plasmids

J Mol Biol. 1983 Jun 5;166(4):557-80. doi: 10.1016/s0022-2836(83)80284-8.


Factors that affect the probability of genetic transformation of Escherichia coli by plasmids have been evaluated. A set of conditions is described under which about one in every 400 plasmid molecules produces a transformed cell. These conditions include cell growth in medium containing elevated levels of Mg2+, and incubation of the cells at 0 degrees C in a solution of Mn2+, Ca2+, Rb+ or K+, dimethyl sulfoxide, dithiothreitol, and hexamine cobalt (III). Transformation efficiency declines linearly with increasing plasmid size. Relaxed and supercoiled plasmids transform with similar probabilities. Non-transforming DNAs compete consistent with mass. No significant variation is observed between competing DNAs of different source, complexity, length or form. Competition with both transforming and non-transforming plasmids indicates that each cell is capable of taking up many DNA molecules, and that the establishment of a transformation event is neither helped nor hindered significantly by the presence of multiple plasmids.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cations
  • DNA, Superhelical
  • Dimethyl Sulfoxide / pharmacology
  • Dithiothreitol / pharmacology
  • Escherichia coli / drug effects
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Plasmids* / drug effects
  • Species Specificity
  • Transformation, Bacterial* / drug effects


  • Cations
  • DNA, Superhelical
  • Dithiothreitol
  • Dimethyl Sulfoxide