title: Evaluation of the in-situ aerobic cometabolism of chlorinated ethenes by toluene-utilizing microorganisms using push-pull tests.
abstract: A series of transport, biostimulation, and activity push-pull tests were performed under induced and natural gradient conditions in a trichloroethene (TCE) and cis-dichloroethene (c-DCE) contaminated aquifer. Transport tests demonstrated the feasibility of injecting and recovering complex solute mixtures from the aquifer. During the biostimulation tests, decreases in toluene concentration and the production of o-cresol as an intermediate oxidation product indicated the presence of toluene-utilizing microorganisms. Activity tests demonstrated that the stimulated microbial community had the ability to transform injected c-DCE and trans-dichloroethene (t-DCE) at similar zero-order rates. Injected isobutene was oxidized to isobutene oxide, which indicated that a toluene ortho-monooxygenase enzyme system was likely responsible for the observed c-DCE and t-DCE transformations. c-DCE zero-order transformation rates in drift push-pull tests were similar to those obtained from traditional push-pull tests (about 0.1 microM/h). Analysis of drift test data using first-order kinetic analysis resulted in similar conclusions as those obtained using zero-order kinetic analyses. When 1-butyne, an inhibitor of toluene ortho-monooxygenase, was added to injected test solutions, the oxidation of toluene, and the transformation of isobutene, c-DCE, and t-DCE were inhibited. The results illustrate how a series of push-pull tests can be used in combination to detect, quantify and confirm in-situ cometabolic microbial transformations.
authors.affiliation: Department of Civil Construction and Environmental Engineering, 220 Owen Hall, Oregon State University, Corvallis, OR 97331, USA. Mohammad.Azizian@oregonstate.edu
authors.forename: Mohammad F
authors.initials: MF
authors.lastname: Azizian
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Istok
authors.forename: Lewis
authors.initials: L
authors.lastname: Semprini
mesh_terms: D000332:Aerobiosis; D001673:Biodegradation, Environmental; D016956:Burkholderia cepacia / Q000201:enzymology; D004000:Dichloroethylenes / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods*; D005240:Feasibility Studies; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D010084:Oxidation-Reduction; D014050:Toluene / Q000378:metabolism*; D014241:Trichloroethylene / Q000378:metabolism*; D014871:Water Microbiology; D014872:Water Movements; D014877:Water Pollution, Chemical; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D004000:Dichloroethylenes; D014241:Trichloroethylene; D014050:Toluene; D006899:Mixed Function Oxygenases