Optimization of technical conditions for the transformation of Lactobacillus acidophilus strains by electroporation

Y. H. Kim, K. S. Han, S. Oh, S. You, S. H. Kim

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Aims: To optimize the conditions for electroporating foreign plasmid DNA into Lactobacillus acidophilus ATCC 43121. Methods and Results: The conditions of electroporation were optimized to improve the transformation efficiency. Plasmid pNZ123 containing multicloning site and chloramphenicol resistance was employed to construct a cloning vector. The optimum electroporation conditions for the maximum transformation efficiency were a pulse strength of 12·5 kV cm-1, a pulse number of 10, a pulse interval of 500 ms, and pNZ123 plasmid DNA concentration of 25 ng μl-1. Under the optimum conditions the transformation efficiency of L. acidophilus ATCC 43121 was 1·84 ± 0·13 × 104 (± standard error of measurements) CFU per μg of plasmid DNA. Other strains of L. acidophilus showed transformation efficiencies ranging from 1·38 ± 0·02 × 104 to 9·32 ± 0·54 × 10 4 under these conditions. A green fluorescent protein (GFP) was successfully expressed and detected by fluorescence microscopy when the pKU::slpA-GFP, pNZ123 containing GFP gene, was transformed in L. acidophilus ATCC 43121 under the optimum conditions. Conclusions: The results suggest that electrical parameters, antibiotic concentration, and host specificity play important roles to determine transformation efficiency of lactobacilli. The optimum conditions for the transformation of L. acidophilus ATCC 43121 may be applied to improve transformation efficiency of other lactobacilli. Significance and Impact of the Study: The optimized conditions for electrotransformation may provide a mean to improve the introduction of foreign DNA into L. acidophilus to be used as a vehicle for a heterologous protein expression.

Original languageEnglish
Pages (from-to)167-174
Number of pages8
JournalJournal of Applied Microbiology
Issue number1
Publication statusPublished - 2005


  • Electroporation
  • Green fluorescent protein
  • Lactobacillus acidophilus
  • Plasmid
  • Transformation efficiency

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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