Collaborator: Entrix Corporation

Remediation of industrial sites contaminated with polychlorinated biphenyls (PCBs) is a serious problem in the US. Biologically based remediation, or bioremediation, has been proposed as a less expensive, more environmentally compatible approach for the degradation of these contaminants. Bioremediation of PCBs by bacterial treatment has been demonstrated at the laboratory and pilot levels and may provide an in situ method of destruction and removal of these environmental toxins. Plant-based bioremediation, or phytoremediation, has been utilized for an extensive array of organic compounds. Plants and plant tissue cultures have been shown to have some capabilities for PCB tolerance and degradation. Microbial activity may serve to provide breakdown products of greater bioavailability and uptake for the plants. In the proposed research, a wide variety of plant species will be selected for introduction and growth in samples of PCB-contaminated sediments. The selected plant taxa will represent a wide range of distantly related taxa to comprise a variety of growth habits, e.g. grass, herbaceous, shrubby, and woody species. Plants will be grown in untreated or sterilized soils, a subset of which will then be inoculated with identified PCB-degrading microbes. Well characterized PCB-degrading strains of the bacterial genera Acinetobacter and Alcaligenes and the fungus Phanerochaete chrysosporium­ will be used independently as supplemental inocula into the treatment rhizosphere. Plant and soil samples shall be obtained and analyzed for total PCB content as well as PCB congener profile. Microbe-specific 16S RNA gene primers will be utilized to monitor the growth of each of the supplemental inocula for each treatment. In the secondary stage of the study, greenhouse conditions will allow for larger and more prolonged plant growth. In addition to larger volume replicates of the initial single-species tests, it will now be possible to use mixed plant and bacterial populations to further mimic natural sites. Such a variety of growth habits and root morphologies may provide enhanced microbial complementation due to greater variability in root exudate resources and soil integration. This research project will determine how plants actually contribute to geochemical distribution or trophic uptake of PCB constituents, with particular attention to the influence of microbial enrichments. Additionally, it will allow characterization of the most beneficial plant species and combinations for both uptake and degradation or phytostimulation of microbial-based remediation. These experiments will lead to the design of a natural treatment scheme for PCB uptake and destruction along with the attendant plant-derived benefits of contaminated water removal and erosion control.