Phytoremediation, the use of plants to remove environmental pollutants, holds great promise to reduce health risks associated with groundwater and soil contamination. Poplar trees can enhance site remediation by vegetative uptake of the contaminant or by enhancing its microbial degradation in the rhizosphere. This latter mechanism is not very effective for removing nitroaromatic contaminants. This project will evaluate the potential for a nitroaromatic-degrading, genetically-engineered microorganism (E. Coli DH5 [pDTG800]) to enhance bioremediation of 2,4,6-trinitrotoluene (TNT) in the poplar rhizosphere. The fate of both 14C-labeled TNT and E. Coli DH5 [pDTG800] will be studied in soil and plant bioreactors. The hypotheses are that 1) bioaugmentation of the poplar rhizosphere with this clone will enhance the mineralization of TNT; and 2) the added clone will maintain its nitroaromatic degradation activity and survive for a longer period of time in soil rhizosphere compared to background (control) soil. This research may lead to a better understanding and a more widespread acceptance of bioremediation in the rhizosphere as an additional tool for reducing health risks associated with environmental pollution.