A practical random mutagenesis system for probiotic Lactobacillus casei using Tn5 transposition complexes

M. Ito, Y. G. Kim, H. Tsuji, M. Kiwaki, K. Nomoto, R. Tanaka, N. Okada, H. Danbara

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Aims: Despite the fact that the entire genome sequence of probiotic Lactobacillus casei has recently been available, their mechanisms of beneficial effects are poorly clarified, probably because of the lack of an efficient mutagenesis system. The aim of this study was to establish a practical random mutagenesis system of L. casei using the Tn5 transposome complexes. Methods and Results: We optimized the conditions for transformation using a plasmid pUCYIT356-1-Not2 and then transposition reaction using Tn5 transposome system for L. casei ATCC 27139. Tn5 insertion library of this strain being consisted of 9408 mutants was constructed by repeating the mutagenesis procedure. To examine the utility of this mutagenesis system, we screened a panel of insertion mutants for nutrient requirements. Six auxotrophic mutants were isolated and their Tn5 insertion sites were determined by inverse PCR, which demonstrated that insertions occur randomly throughout the whole bacterial genome. Conclusions: Tn5 transposome system functioned efficiently to generate transposon insertion mutants of L. casei and enabled to construct useful L. casei Tn5 insertion library at optimized conditions for transformation and transposition. Significance and Impact of the Study: The availability of this system facilitates the study of the mechanisms of beneficial effects of L. casei for human health.

Original languageEnglish
Pages (from-to)657-666
Number of pages10
JournalJournal of Applied Microbiology
Issue number2
Publication statusPublished - 2010 Aug
Externally publishedYes


  • EZ::TN transposome
  • Lactobacillus casei
  • Tn5 transposon
  • auxotrophic requirement
  • electroporation
  • probiotics
  • random mutagenesis

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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