High efficiency transformation of E. coli by high voltage electroporation

Nucleic Acids Res. 1988 Jul 11;16(13):6127-45. doi: 10.1093/nar/16.13.6127.


E. coli can be transformed to extremely high efficiencies by subjecting a mixture of cells and DNA to brief but intense electrical fields of exponential decay waveform (electroporation). We have obtained 10(9) to 10(10) transformants/micrograms with strains LE392 and DH5 alpha, and plasmids pUC18 and pBR329. The process is highly dependent on two characteristics of the electrical pulse: the electric field strength and the pulse length (RC time constant). The frequency of transformation is a linear function of the DNA concentration over at least six orders of magnitude; and the efficiency of transformation is a function of the cell concentration. Most of the surviving cells are competent with up to 80% transformed at high DNA concentration. The mechanism does not appear to include binding of the DNA to the cells prior to entry. Possible mechanisms are discussed and a simple procedure for the practical use of this technique is presented.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Bacterial / analysis
  • Electrophoresis
  • Escherichia coli / genetics*
  • Mathematics
  • Plasmids
  • Transformation, Bacterial*


  • DNA, Bacterial