Superfund Research Program
Enhanced Endophyte: Poplar System for Remediation of Organic Contaminants
Project Leader: Mark P. Elless
Grant Number: R43ES020099
Funding Period: Phase I: April 2011 - September 2011
Edenspace Systems Corporation, in collaboration with Dr. Sharon Doty's research group at the University of Washington (UW), is developing a novel phytoremediation technology to address environmental contamination by organic pollutants. Phytoremediation with poplar trees has been utilized for over a decade to extract contaminants such as trichloroethylene (TCE) from contaminated soils and shallow groundwater. The high rate of transpiration in poplar allows the trees to remove water-soluble contaminants such as TCE from the environment. TCE, however, is toxic to poplar, reducing growth, and is readily volatilized through evapotranspiration to precipitate in another location. Through the use of endophytic fungi and bacteria that associate with poplar and are capable of metabolizing TCE, Edenspace and UW are developing an innovative plant-based remediation system that will degrade the organic contaminant in planta, reducing both the toxicity to the plant and the amount released aerially through transpiration while also enabling the microbes to act on subsurface contamination through the tree's deep (>5m) root system. A single mature tree is expected to process over one hundred liters of water per day.
In Phase I of this project the researchers are:
1) Demonstrating improved degradation of TCE by the poplar inoculated with endophytes compared to un-inoculated. The Doty laboratory developed efficient inoculation methods for their specific endophytes and will be ready to assess their benefit on TCE degradation in soils and water spiked with the contaminants.
2) Demonstrating the endophytes that provide phytoremediation benefits persist in the inoculated poplar under field conditions. Numerous microbes have been engineered with improved abilities to degrade contaminants, but when they are introduced into field sites they do not necessarily persist in the environment due to competition with natural microbes. The field trials examine both the short term growth impact of the endophytes on poplar growing in a TCE contaminated site and whether the endophytes are still present in the poplar after two months in the field.
3) Demonstrating the biomass from the inoculated poplar used for phytoremediation can be used as a biofuel feedstock as efficiently as poplar biomass grown in clean soil. Edenspace routinely measures the efficiency of biomass conversion to fermentable sugars with a variety of feedstocks, including poplar. Confirming that the endophyte-containing poplar are converted into fermentable sugars as readily and do not contain more fermentation inhibitors than un-inoculated poplar will allow the poplar developed in this project to produce biofuels in addition to phytoremediation.