Rhizoremediation of trichloroethylene by a recombinant, root-colonizing Pseudomonas fluorescens strain expressing toluene ortho-monooxygenase constitutively

Appl Environ Microbiol. 1998 Jan;64(1):112-8. doi: 10.1128/AEM.64.1.112-118.1998.


Trichloroethylene (TCE) was removed from soils by using a wheat rhizosphere established by coating seeds with a recombinant, TCE-degrading Pseudomonas fluorescens strain that expresses the tomA+ (toluene o-monooxygenase) genes from Burkholderia cepacia PR1(23)(TOM23C). A transposon integration vector was used to insert tomA+ into the chromosome of P. fluorescens 2-79, producing a stable strain that expressed constitutively the monooxygenase at a level of 1.1 nmol/min.mg of protein (initial TCE concentration, 10 microM, assuming that all of the TCE was in the liquid) for more than 280 cell generations (36 days). We also constructed a salicylate-inducible P. fluorescens strain that degraded TCE at an initial rate of 2.6 nmol/min.mg of protein in the presence of 10 microM TCE [cf. B. cepacia G4 PR1(23) (TOM23C), which degraded TCE at an initial rate of 2.5 nmol/min.mg of protein]. A constitutive strain, P. fluorescens 2-79TOM, grew (maximum specific growth rate, 0.78 h-1) and colonized wheat (3 x 10(6) CFU/cm of root) as well as wild-type P. fluorescens 2-79 (maximum specific growth rate, 0.77 h-1; level of colonization, 4 x 10(6) CFU/cm of root). Rhizoremediation of TCE was demonstrated by using microcosms containing the constitutive monooxygenase-expressing microorganism, soil, and wheat. These closed microcosms degraded an average of 63% of the initial TCE in 4 days (20.6 nmol of TCE/day.plant), compared to the 9% of the initial TCE removed by negative controls consisting of microcosms containing wild-type P. fluorescens 2-79-inoculated wheat, uninoculated wheat, or sterile soil.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biodegradation, Environmental
  • Burkholderia cepacia / genetics
  • Chromosomes, Bacterial / genetics
  • DNA Transposable Elements
  • Gene Expression
  • Mixed Function Oxygenases / genetics*
  • Mixed Function Oxygenases / metabolism
  • Mutagenesis, Insertional
  • Plant Roots / microbiology*
  • Plasmids
  • Pseudomonas fluorescens / genetics*
  • Pseudomonas fluorescens / growth & development
  • Pseudomonas fluorescens / metabolism*
  • Recombination, Genetic*
  • Restriction Mapping
  • Seeds / microbiology
  • Soil Microbiology
  • Trichloroethylene / metabolism*
  • Triticum / microbiology


  • DNA Transposable Elements
  • Trichloroethylene
  • Mixed Function Oxygenases
  • toluene ortho-monooxygenase