Frequency of horizontal gene transfer of a large catabolic plasmid (pJP4) in soil

J. W. Neilson, K. L. Josephson, I. L. Pepper, R. B. Arnold, G. D. Di Giovanni, N. A. Sinclair

Research output: Contribution to journalArticle

82 Scopus citations

Abstract

Limited work has been done to assess the bioremediation potential of transfer of plasmid-borne degradative genes from introduced to indigenous organisms in the environment. Here we demonstrate the transfer by conjugation of the catabolic plasmid pJP4, using a model system with donor and recipient organisms. The donor organism was Alcaligenes eutrophus JMP134 and the recipient organism was Variovorax paradoxus isolated from a toxic waste site. Plasmid pJP4 contains genes for mercury resistance and 2,4- dichlorophenoxyacetic (2,4-D) acid degradation. A transfer frequency of approximately 1/103 donor and recipient cells (parent cells) was observed on solid agar media, decreasing to 1/105 parent cells in sterile soil and finally 1/106 parent cells in 2,4-D-amended, nonsterile soil. Presumptive transconjugants were confirmed to be resistant to Hg, to be capable of degrading 2,4-D, and to contain a plasmid of size comparable to that of pJP4. In addition, we confirmed the transfer through PCR amplifications of the tfdB gene. Although transfer of pJP4 did occur at a high frequency in pure culture, the rate was significantly decreased by the introduction of abiotic (sterile soil) and biotic (nonsterile soil) stresses. An evaluation of the data from this model system implies that the reliance on plasmid transfer from a donor organism as a remediative strategy has limited potential.

Original languageEnglish (US)
Pages (from-to)4053-4058
Number of pages6
JournalApplied and environmental microbiology
Volume60
Issue number11
StatePublished - Nov 10 1994

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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