Tuesday, October 30th – 11:05 am – 11:30 am*

New biotech specifically tailored for environmental remediation of groundwater utilizes bacterial endophyte enhanced poplar trees used for internal, onsite, remediation of Trichloroethylene (TCE) and Gas/Oil PAH volatile organic compounds (VOC’s). Our Technology helps address remediation of two widespread environmental pollutant classes common in groundwater plumes associated with industrial manufacturing, fuel and chemical storage areas. We had previously isolated and characterized a natural bacterial endophyte, Enterobacter sp. strain PDN3, of poplar trees, that rapidly metabolizes TCE, releasing chloride ion. Findings from a successful four-year field trial of endophyte-assisted poplar tree phytoremediation on the Middlefield-Ellis-Whisman Superfund in the Silicon Valley of California located on NASA-Ames Research Park will be presented. The inoculated poplar trees exhibited increased growth and reduced TCE phytotoxic effects with a 32% increase in trunk diameter compared to control poplar trees. The inoculated trees excreted 50% more chloride ion into the rhizosphere, indicative of increased TCE metabolism in planta. Mass Spec data from tree core analysis provided further supporting evidence of the enhanced rate of degradation of the chlorinated solvents in the inoculated trees. NASA-ERT test well groundwater analyses demonstrated a marked decrease in concentration of TCE and its derivatives from the tree-associated groundwater plume. The concentration of TCE decreased from 300 µg/L upstream of the planted area to less than 5 µg/L downstream of the planted area. TCE derivatives were similarly removed with cis-1,2-dichloroethene decreasing from 160 µg/L to less than 5 µg/L and trans-1,2-dichloroethene decreasing from 3.1 µg/L to less than 0.5 µg/L downstream of the planted trees. 1,1-dichloroethene and vinyl chloride both decreased from 6.8 and 0.77 µg/L, respectively, to below the reporting limit of 0.5 µg/L providing strong evidence of the ability of the endophyte inoculated trees to effectively remove TCE from affected groundwater. The combination of native pollutant-degrading endophytic bacteria and fast-growing, thirsty poplar tree systems offers a readily employable, cost-effective approach for the degradation of TCE, and may help mitigate potential transfer up the food chain, volatilization to the atmosphere, as well as direct phyto-toxic impacts to trees used in this type of groundwater phytoremediation. Our MEW, NASA-Ames field observations have further extended into new sites where the PDN3 endophyte approach is being used by Environmental Engineering Firms.
Furthermore, we have recent successful field deployments of a second poplar tree bacterial endophyte Pseudomonas putida strain PD1 that is responsible for degrading Petroleum VOC’s (phenanthrene, DRO/GRO, benzene). We will present results from establishing these strains in Mixed Waste Groundwater Poplar Tree Phytoremediation Sites for addressing multiple contaminant classes [e.g., Chlorinated Solvents (TCE, DCE, VC), PAH’s (DRO/GRO, benzene) and 1-4 Dioxane]. These VOC’s in groundwater are all now being simultaneously treated by combining both PDN3 + PD1 naturally occurring bacterial strains in Co-Inoculated Endophyte Assisted Poplar Trees.

Primary Author / Conference Presenter:
Dr. John Freeman
Mountain View, California, USA

Dr. Chris Cohu PPCU , Glenwood Springs, CO
Dr. Sharon Doty University of Washington, Seattle, WA
Dr. Joel Burken Missouri S and T, Rolla, MO
Dr. Mike Blaylock Eden Space, Purcellville, VA

*date & time subject to change