title: Metabolism of the soil and groundwater contaminants, ethylene dibromide and trichloroethylene, by the tropical leguminous tree, Leuceana leucocephala.
abstract: Ethylene dibromide (EDB; dibromoethane) and trichloroethylene (TCE) are hazardous environmental pollutants. The use of plants to treat polluted sites and groundwater, termed phytoremediation, requires plants that can both effectively remove the pollutant as well as grow in the climatic region of the site. In this paper, we report that the tropical leguminous tree, Leuceana leucocephala var. K636, is able to take up and metabolize EDB and TCE. The plants were grown in sterile hydroponic solution without its symbiont, Rhizobium. EDB and TCE were both metabolized by the plant, as indicated by the formation of bromide ion from EDB and trichloroethanol from TCE. Each plant organ was independently capable of debromination of EDB. L. leucocephala is being used to treat perched groundwater as part of a remedial alternative to address an accidental EDB spill in Hawaii. Bromide levels of plant tissues from the trees grown in the phytoremediation treatment cells at the Hawaii Site were elevated, indicating uptake and degradation of brominated compounds in the trees. This report is the first evidence of a tropical tree effectively metabolizing these common organic pollutants.
authors.affiliation: Department of Biochemistry, Box 357350, University of Washington, Seattle, WA 98195, USA. sldoty@u.washington.edu
authors.forename: Sharon Lafferty
authors.initials: SL
authors.lastname: Doty
authors.forename: Tanya Qing
authors.initials: TQ
authors.lastname: Shang
authors.forename: Angela M
authors.initials: AM
authors.lastname: Wilson
authors.forename: Allison Leigh
authors.initials: AL
authors.lastname: Moore
authors.forename: Lee A
authors.initials: LA
authors.lastname: Newman
authors.forename: Stuart Edward
authors.initials: SE
authors.lastname: Strand
authors.forename: Milton Paul
authors.initials: MP
authors.lastname: Gordon
mesh_terms: D001673:Biodegradation, Environmental; D015946:Ethylene Dibromide / Q000378:metabolism*; D007887:Fabaceae / Q000502:physiology*; D012231:Rhizobium / Q000502:physiology; D012989:Soil Pollutants / Q000378:metabolism*; D012997:Solvents / Q000378:metabolism*; D014241:Trichloroethylene / Q000378:metabolism*; D014329:Tropical Climate; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D012989:Soil Pollutants; D012997:Solvents; D014874:Water Pollutants, Chemical; D015946:Ethylene Dibromide; D014241:Trichloroethylene