Phytoremediation of Organic Pollutants Using Transgenic Plants
Exposure to toxic volatile organic compounds (VOCs) continues to pose a significant risk to human health. Halogenated VOCs such as chloroform, carbon tetrachloride (CT) and trichloroethylene (TCE), along with benzene and other single-ring aromatics are among the most common contaminants in water and air. These compounds share a susceptibility to oxidation by the mammalian hepatic cytochrome P450 2E1. In past NIEHS-funded work at UW, we have demonstrated that TCE and CT are oxidized by axenic poplar cell cultures using a pathway similar to that in mammals and that wild-type poplar are able to take up and degrade TCE and CT. Our work has led to the realization that TCE and CT uptake by wild-type plants is too weak to significantly reduce their concentration in root zone water, providing motivation for the development of plants with increased degradative activity toward VOCs. Toward this end we have expressed mammalian cytochrome P450 2E1 (CYP2E1) in plants, achieving orders of magnitude greater oxidation of TCE in transgenic poplar. We are presently engaged in testing TCE degradation by wild-type and CYP2E1 transgenic poplar at field scale in a test bed facility capable of mass balance measurements. We are also studying the pathways and genetics of VOC metabolism in plants, and to developing new applications for genetically modified phytoremediation.
