High-efficiency transformation of Listeria monocytogenes by electroporation of penicillin-treated cells

Gene. 1990 Sep 28;94(1):129-32. doi: 10.1016/0378-1119(90)90479-b.


A procedure has been developed for electroporation-mediated transformation of Listeria monocytogenes with plasmid DNA. The method was optimized for intact cells of L. monocytogenes 23074 by determining the effects of field strength, cell density, and plasmid DNA topology. Transformation efficiencies were dramatically increased when cells were treated with penicillin. Optimum frequencies of transformation (4 x 10(6) transformants/microgram DNA) were obtained when cells were grown in 10 micrograms/ml of penicillin G and electroporated at a field strength of 10 kV/cm. Using this procedure, transformation of relaxed plasmid DNA from ligation reactions provided 1 x 10(4) transformants/microgram DNA, allowing direct molecular cloning of DNA into this organism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Bacterial / genetics
  • Electric Stimulation
  • Listeria monocytogenes / drug effects
  • Listeria monocytogenes / genetics*
  • Penicillin G / pharmacology*
  • Plasmids
  • Transformation, Bacterial / drug effects*


  • DNA, Bacterial
  • Penicillin G