In the electroporation process, the bacteria are mixed with DNA and briefly exposed to a strong electric field. It is important that the recipient cells first be washed extensively in buffer with very low ionic strength such as distilled water. The buffer usually also contains a nonionic solute such as glycerol to prevent osmotic shock. The brief electric fields across the cellular membranes might created artificial pores of H2O lined by phospholipid head groups. DNA can pass through these temporary hydrophilic pores. Electroporation works with most types of cells, including most bacteria, unlike the methods mentioned above, which are very specific for certain species. Also, electroporation can be used to introduce linear chromosomal and circular plasmid DNAs into cells.
Snyder, Larry and Wendy Champness. Molecular Genetics of Bacteria. 3rd ed. Virginia: ASM Press, 2007.