Electroporation-induced transformation of Escherichia coli: evaluation of a square waveform pulse.

Four strains of Escherichia coli were tested for electroporation-induced plasmid transformation using a high voltage pulse in a square waveform. Conditions for optimal transformation were determined for each strain and transformation frequencies found to be comparable to those reported previously for E. coli with a sinusoidal waveform of exponential decaying pulse.