Transformation of group A streptococci by electroporation

The introduction, via electroporation, of free plasmid DNA into three strains of Streptococcus pyogenes is described. The method is very simple and rapid and efficiencies vary from 1 × 103 to 4 × 104 per μg of DNA. The method was also used to introduce an integrative plasmid and transformants were obtained, albeit at a somewhat lower frequency (2 × 102). Some of the plasmids used in this study are derivatives of the Lactococcus lactis subsp. cremoris Wg2 plasmid pWV01. These broad host range vectors replicate in Gram-positives as well as Gram-negatives (viz. Escherichia coli). Here we show that they also replicate in S. pyogenes and S. sanguis.