INBRE-2 MICROBIAL DETOXIFICATION OF POLYCHLORINATED BIPHENYLS (PCBS) IN SOIL

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Polychlorinated biphenyls (PCBs) are persistent organic pollutants that bioaccumulate in the food chain and pose risks to human health. In Alaska, PCB contamination is present in many formerly used defense sites (FUDS), including remote areas near subsistence-fed human populations. Conventional methods for PCB cleanup are extremely expensive, particularly in remote areas. Alternatively, bioremediation is an attractive means to detoxify PCB-contaminated soils and reduce human exposure. Our primary objective is to develop strategies for accelerating PCB detoxification that capitalize on the ability of native Alaskan plants to promote microbial PCB degradation in soil. Previous studies indicate that certain plants may release secondary aromatic compounds from their roots that effectively facilitate long-term biostimulation of PCB degrading bacteria in the rhizosphere, in a process known as rhizoremediation. Alaskan tree species are known to possess extremely high levels of aromatic compounds, and thus would be particularly promising for facilitating detoxification of PCB-contaminated sites, including contaminated FUDS sites across the state. Using microcosm studies and molecular and cultivation-based microbiological techniques, coupled with intensive chemical analyses and modeling, we will evaluate different strategies for accelerating microbial PCB detoxification and reducing potential for PCB transport. Reduction in toxicity will be evaluated using chemical analysis of PCBs, including coplanar dioxin-like congeners and toxic enantiomers, followed by calculations of the change in toxic equivalency quotient (TEQ) of PCBs based on the established toxic equivalency factor (TEF) of individual congeners and enantiomers.