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Current Microbiology

, Volume 42, Issue 3, pp 160–167 | Cite as

Effect of Genomic Location on Horizontal Transfer of a Recombinant Gene Cassette Between Pseudomonas Strains in the Rhizosphere and Spermosphere of Barley Seedlings

  • Gitte Sengeløv
  • Kirstine Jessen Kristensen
  • Anders Hay Sørensen
  • Niels Kroer
  • Søren J. Sørensen
Article

Abstract

The use of genetically engineered bacteria in natural environments constitutes a risk of transfer of recombinant DNA to the indigenous bacteria. However, chromosomal genes are believed to be less likely to transfer than genes on mobilizable and conjugative plasmids. To study this assumption, horizontal transfer of a recombinant gene cassette inserted into the chromosome of a Pseudomonas stutzeri strain, into a mobilizable plasmid (pAGM42), and into a conjugative plasmid (pKJK5) isolated from barley rhizosphere was investigated. Horizontal transfer efficiencies of the gene cassette inserted into a conjugative plasmid was 8.20 × 10−3 transconjugants/(donors × recipients)1/2 in the rhizosphere and 4.57 × 10−2 transconjugants/(donors × recipients)1/2 in the spermosphere. Mobilization of the plasmid pAGM42 by the plasmids RP4 and pKJK5 was also detected at high levels in the microcosms, transfer efficiencies were up to 4.36 × 10−3 transconjugants/(donors × recipients)1/2. Transfer of chromosomal encoded genes could not be detected in the microcosms by conjugation or transformation. However, transformation did occur by using the same bacterial strains under laboratory conditions. The rhizosphere and especially the spermosphere thus proved to be hot spot environments providing favorable conditions for gene transfer by mobilization and conjugation, but these environments did not support transformation at a detectable level.

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Copyright information

© Springer-Verlag New York Inc. 2001

Authors and Affiliations

  • Gitte Sengeløv
    • 1
  • Kirstine Jessen Kristensen
    • 1
  • Anders Hay Sørensen
    • 1
  • Niels Kroer
    • 2
  • Søren J. Sørensen
    • 1
  1. 1.Department of General Microbiology, University of Copenhagen, Sølvgade 83 H, DK-1307 Copenhagen K, DenmarkDK
  2. 2.Department of Marine Ecology and Microbiology, National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, DenmarkDK

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