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CONSTITUTIVE DEGRADATION OF TRICHLOROETHYLENE BY AN ALTERED BACTERIUM IN A GAS-PHASE BIOREACTOR
Citation:
Shields, M., M. Reagin, R. Gerger, C. Somerville, R. Schaubhut, R. Campbell, AND J. Hu-Primmer. CONSTITUTIVE DEGRADATION OF TRICHLOROETHYLENE BY AN ALTERED BACTERIUM IN A GAS-PHASE BIOREACTOR. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-94/204.
Description:
Pseudomonas cepacia G4 expresses a unique toluene ortho-monooxygenase (Tom) that enables it to degrade toluene and trichloroethylene (TCE). ransposon mutants of G4 have been isolated that constitutively express Tom. wo fixed-film bioreactor designs were investigated for the exploitation of one such constitutive strain (G4PR1) in the degradation of vapor-phase TCE. ne received air-entrained TCE along with a continuous inflow of nutrient medium. train G4 was unable to degrade TCE in such a vapor-phase bioreactor (100% re-feed), whereas PR1, present at > 1.4 x 10 8 bacteria gram-1 of the support material, completely removed the recirculating 80 uM (10 mg TCE/L air) TCE. ests of strain PR1 in a continuous-flow vapor-phase reactor resulted in an average of 92.1% removal of TCE at an average input concentration of 12.6 mM (2 mg/L) TCE (at 0% re-feed) over a 72-h test. he genes responsible for this and the oxidative cleavage of catechol have been cloned into pGEM3Z as an 11 kb Eco RI fragment (pMS64) and expressed in Escherichia coli. . coli (pMS64) is capable of converting toluene to ortho-cresol, ortho-cresol to 3-methylcatechol, and phenol to catechol, and degrading TCE in a batch liquid reactor. NA probe analysis indicates that the genes responsible for this toluene catabolic pathway are located on a large plasmid of G4 (> i 50 kb) termed pG4L. e propose that pG4L will serve as the archetype for a new class of catabolic plasmid known as Tom, which encodes an ortho-hydroxylation pathway for the degradation of benzene, toluene, o-xylene, cresols, and phenol.