Lactobacillus transformation (Berthier 1996)

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General guidelines for the electro-transformation of Lactobacillus sake as described by Berthier et al. and as used by Alegre et al. with Lactobacillus plantarum.


  • 50 ul of L.plantarum competent cells
  • In vitro modified plasmid DNA
  • MRS media + antibiotic
  • Stock solution of MgCl2
  • Stock Solution of Glucose


  1. Ensure that the in vitro modification of DNA protocol for Lactobacillus plantarum has been followed.
  2. Thaw 50 ul of competent cells on ice from aliquots in -80°C freezer.
  3. Add between 1 ng and 3 ug of plasmid DNA in 5 ul of TE buffer to 50 ul of freshly prepared competent cells and transfer to prechilled cuvette for electroporation (interelectrode distance 1 mm).
  4. Electroporation done at 13 Kv cm-1 (time constant: 2-4 ms), Set electroporation machine to 25μF and 200 Ω.
  5. Add 500 ul of MRS media containing 80mM MgCl2 and 55mM Glucose
  6. Incubate for 2 hours at 30°C.
  7. Plate cells on MRS plates + antibiotic resistance.


All questions, input and feedback are welcome!

I've had trouble using this protocol to transform some Lactobacillus plantarum strains. Changing the glycine concentration to 8% and the sucrose concentration to 0.9M gave me fantastic results.


Berthier, F., Zagorec, M., Champomier-Verge`s, M., Ehrlich, S.D. and Morel-Deville, F. (1996) Efficient transformation of Lactobacillus sake by electroporation. Microbiology 142, 1273–1279.

Alegre et al. (FEMS Microbiology Letters 241 (2004) 73–77)



or instead, discuss this protocol. -->