• Title/Summary/Keyword: Phosho-$\beta$-galactosidase gene

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Molecular cloning of phospho-$\beta$-galactosidase gene of lactobacillus casei in escherichia coli (Lactobacillus casei의 phospho-$\beta$-galactosidase 유전자의 대장균내 분자클로닝)

  • 문경희;박정희;최순영;이유미;김태한;김연수;민경희
    • Korean Journal of Microbiology
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    • v.27 no.3
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    • pp.188-193
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    • 1989
  • Gene for lactose catabolism in Lactobacillus casei SW-M1 was encoded by a 60Kb metabolic plasmid. A derivative of only 10kb, pPlac 15 of recombinant plasmid, was constructed by introducing into pBR322 and was cloned into E. coli using restriction endonuclease Pst I. A 10kb insery DNA in plasmid pBR322 was identified as a gene encoded phospho-$\beta$-galactosidase by the determination of enzyme activity. Phospho-$\beta$-galactosidase was apparently expressed in E. coli. The enzyme activities of cell-free extract from transformant E. coli HB101 carrying pPLac 15 DNA were not different from that of L. casei as a donor strain on the basis of enzyme properites. However, specific activity of phospho-$\beta$-galactosidase in the cloned strain with Lac $Y^{-}$ phenotype of E. coli HB101 was lower than that in L. casei strain.

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Phospho-$\beta$-galactosidase gene located on plasmid in lactobacillus casei (플라스미드에 존재하는 lactobacillus casei의 phospho-$\beta$-galactosidases 유전자)

  • 문경희;박정희;최순영;이유미;김태한;하영칠;민경희
    • Korean Journal of Microbiology
    • /
    • v.27 no.3
    • /
    • pp.181-187
    • /
    • 1989
  • Plasmid DNA was isolated from Lactobacillus casei SW-M1($Lac^{+}$strain). The curing frequencies of pPLac plasmid from L. casei SW-M1 showed 43% for acriflavin treatment and 53% for ethidium bromide treatment after 3 times transfer. On the charaterization of pPLac plasmid, it was found that the plasmid contained gene encoding phospho-$\beta$-galactosidase for lactose utilization. Lactose-PTS(phosphotransferase system)was involved in membrane transport system in $Lac^{+}$ strain. Induction of phospho-$\beta$-galactosidase was specially effective by galactose, lower effect with lactose and glucose but not by IPTG(isopropyl-$\beta$-D-thiogalactoside). This result showed that induction of phospho-$\beta$-galactosidase by IPTG did not appeared. The catabolite repression of phospho-$\beta$-galactosidase synthesis by glucose was not found in L. casei.

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