Rhizosphere competitiveness of trichloroethylene-degrading, poplar-colonizing recombinant bacteria

H. Shim, S. Chauhan, D. Ryoo, K. Bowers, S. M. Thomas, K. A. Canada, J. G. Burken, T. K. Wood

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Indigenous bacteria from poplar tree (Populus canadensis var. eugenei 'Imperial Carolina') and southern California shrub rhizospheres, as well as two tree-colonizing Rhizobium strains (ATCC 10320 and ATCC 35645), were engineered to express constitutively and stably toluene o-monooxygenase (TOM) from Burkholderia cepacia G4 by integrating the tom locus into the chromosome. The poplar and Rhizobium recombinant bacteria degraded trichloroethylene at a rate of 0.8 to 2.1 nmol/min/mg of protein and were competitive against the unengineered hosts in wheat and barley rhizospheres for 1 month (colonization occurred at a level of 1.0 x 105 to 23 x 105 CFU/cm of root). In addition, six of these recombinants colonized poplar roots stably and competitively with populations as large as 79% ± 12% of all rhizosphere bacteria after 28 days (0.2 x 105 to 31 x 105 CFU/cm of root). Furthermore, five of the most competitive poplar recombinants (e.g., Pb3-1 and Pb5-1, which were identified as Pseudomonas sp. strain PsK recombinants) retained the ability to express TOM for 29 days as 100% ± 0% of the recombinants detected in the poplar rhizosphere expressed TOM constitutively.

Original languageEnglish (US)
Pages (from-to)4673-4678
Number of pages6
JournalApplied and environmental microbiology
Issue number11
StatePublished - 2000

All Science Journal Classification (ASJC) codes

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


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