title: Rhizosphere competitiveness of trichloroethylene-degrading, poplar-colonizing recombinant bacteria.
abstract: 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 10(5) to 23 x 10(5) 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 10(5) to 31 x 10(5) 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.
authors.affiliation: Department of Chemical Engineering, University of Connecticut, Storrs, Connecticut 06269-3222, USA.
authors.forename: H
authors.initials: H
authors.lastname: Shim
authors.forename: S
authors.initials: S
authors.lastname: Chauhan
authors.forename: D
authors.initials: D
authors.lastname: Ryoo
authors.forename: K
authors.initials: K
authors.lastname: Bowers
authors.forename: S M
authors.initials: SM
authors.lastname: Thomas
authors.forename: K A
authors.initials: KA
authors.lastname: Canada
authors.forename: J G
authors.initials: JG
authors.lastname: Burken
authors.forename: T K
authors.initials: TK
authors.lastname: Wood
mesh_terms: D001673:Biodegradation, Environmental; D001467:Hordeum / Q000382:microbiology; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000382:microbiology*; D011549:Pseudomonas / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D011995:Recombination, Genetic; D012231:Rhizobium / Q000254:growth & development / Q000378:metabolism; D014197:Trees / Q000254:growth & development / Q000382:microbiology*; D014241:Trichloroethylene / Q000378:metabolism*; D014908:Triticum / Q000382:microbiology
chemical_list: D014241:Trichloroethylene; D006899:Mixed Function Oxygenases; C093480:toluene ortho-monooxygenase