Optimized conditions for electrotransformation of bacteria are related to the extent of electropermeabilization

Electropulsation is a simple and efficient way to introduce cloned genes into a variety of cell types, even with walled species. In the case of bacteria, we observed no direct correlation between survival rate and transformation yield. In the present work, we show that the yield of transformation is directly related to the level of the electric-field induced level of cell permeabilization. From experiments on Escherichia coli, it was confirmed that the extent of associated ATP leakage was a reliable assay. This approach was extended to other strains, such as Salmonella typhimurium, which to date had not been electrotransformed by plasmids.