Endophyte Assisted Phytoremediation of TCE and Derivatives Using Hybrid Poplar Trees
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This document summarizes a study on using hybrid poplar trees and their associated endophytic microbes to remediate trichloroethylene (TCE) and derivatives from contaminated groundwater. Researchers screened poplar endophytes and identified one that could degrade TCE into chloride ions. Field tests showed poplar trees inoculated with this endophyte had higher chloride levels in soil, indicating TCE degradation, compared to uninoculated trees. Monitoring wells near inoculated tree plots also showed decreasing TCE and PCE levels over time, demonstrating the endophyte-assisted phytoremediation approach.
Endophyte Assisted Phytoremediation of TCE and Derivatives Using Hybrid Poplar Trees
- 1. Endophyte Assisted Phytoremediation of TCE and Derivatives Using Hybrid Poplar Trees John L. Freeman, PhD C.S.O. Intrinsyx NASA-Ames Research Park 1
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- 3. Advanced Knowledge Applicable Technologies Phytoremediation / Phytomining Molecular Biology Plant Biochemistry Soil/Water Chemistry Plant Physiology Agronomy Multidisciplinary Team Based Supportive Approach to Projects Microbiology Ecology Genetics Environmental Engineering 3
- 4. Phyto-remediation: Using plants and their associated microbes to clean up pollution 4
- 5. Poplar and willow can grow in extreme environments 5
- 6. Poplar is a Tree of Choice for Groundwater Phytoremediation Deep root up to 30 feet down Can be deep planted down to 8 ft bare trees. 15 feet down using tree wells. Hybrid poplar High rate of Hydrological Conductivity Single mature tree can use >3000 gallons per year >50 gallons per day EPA guidance www.clu-in.org https://clu-in.org/products/intern/phytotce.htm 6
- 7. Using Poplar, Cottonwood and Willow endophytes “Screened the tree micro-biome for an Endophyte that can degrade TCE” 7
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- 9. Applied and Environmental Microbiology 2012, 78(9): p. 3504–3507 9
- 10. Endophyte Showed TCE Degradation Using Color indicator for TCE in agarose media Identified 1 Poplar Endophyte , Showed enhanced TCE Degradation and Chloride production in liquid and solid media Endophyte degrading TCE Endophyte degrading TCE into Cl Applied and Environmental Microbiology 2012, 78(9): p. 3504–3507 10
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- 13. Test plots at Moffett Field after planting. 13
- 14. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Inoculated Uninoculated 1yearGrowthRating 311-93 OP-367 Growth Benefits/TCE tolerance from Endophyte Inoculation 2014 14
- 15. Tree trunk diameter at breast height in (cm) 15
- 16. 0 500 1000 1500 2000 2500 6i 6c 6a 6f 6b 6k 6d 6e 6h 6j 2j 2k 2i 2l 2c 2d 2g 2f 2h 2a 2b 2e 2h cln1 cln2 cln3 cln4 cln5 cln6 cln7 cln8 cln9 cln10 SurfaceSoilChlorideConcentration (ppm) Soil Sample Chloride Concentration Analysis of TCE contaminated Soil with variety OP367 in 2015 6i 6c 6a 6f 6b 6k 6d 6e 6h 6j 2j 2k 2i 2l 2c No-TCE clean soil Same area Endophyte Inoculated Un-inoculated RESULTS The results from the chloride analysis are demonstrated in the graph. On average, there was ~44% more chloride found in surface soil that was taken from two year old trees that were originally inoculated with the native endophyte in the TCE contaminated site. Soil samples were also taken from the local site that was not contaminated with TCE. The average chloride concentration of soil taken from un-inoculated plants was 1018.8 ppm while the average concentration of soil from inoculated trees was 1528.9 ppm. The average chloride concentration of soil taken from a clean site was 981.5 ppm. Chloride concentrations can range from 0.4 to 3000ppm, depending on the site’s proximity to salt water. Given that the NASA Ames Research Center sits next to the San Francisco Bay, it is not unreasonable to have a relatively high chloride concentration as a baseline. The TCE is being degraded and exuded by roots in upper soil zone as Chloride 16
- 17. Average Soil chloride levels in tree associated rhizosphere (Cl- ppm) 2015 17
- 18. Figure 1 Trends in Plant Science 2017 22, 236-248DOI: (10.1016/j.tplants.2016.12.004) Copyright © 2016 Elsevier Ltd Mechanisms Contributing to Cl− Exclusion from the Leaf Cytosol Thereby Leading to Cl− Tolerance. 18
- 19. TCE Degraded into Cl Which is then excreted/exported by roots int - soil as Cl Root Cl- efflux proteins Accumulation Overview of TCE Phytoremediation Mechanisms Soil solution/soluble Degradation TCE into Cl 19
- 20. Test Well 2 Fall 2016 20
- 21. 0.066 223.08 7.04 10.29 0 50 100 150 200 250 OP367 + endophyte TCE 0.066 OP367 - control uninoculated TCE 223.08 OP367 + endophyte PCE 7.04 OP367 - control uninoculated PCE 10.29 Concentration(ppb) Phyto-detection= Using Solid phase micro-extraction + electron capture detection of TCE and PCE in tree cores we can detect presence of internal contaminants and degradation rates Trees inoculated* with TCE/PCE degrading endophytes consistently had less internal TCE and PCE and are tolerant / grew better than un-inoculated control n=10 trees each treatment * * TCE +Endo TCE PCE +Endo PCE
- 22. TCE levels in tree core samples (TCE ppb) N=30 trees each treatment Tree core process allows TCE, PCE, DCE tests to be performed on trees over ground water plumes can help map concentrations grids or rings of trees around potential hot spots monitor plume movement changes Endophyte assisted phytoremediation efficacy Less expensive than test wells 0 50 100 150 p=0.083 0 5 10 15 20 p=0.04 Plot 2 Plot 3 0 20 40 60 80 100 p=0.079 Plots 2 and 3 0 20 40 60 p=0.087 All Plots TCE(µgkg-1)TCE(µgkg-1) a b c d Uninoculated Uninoculated InoculatedInoculated
- 24. Phytoremediation Poplar Planting site2 Test Well Poplar 01 Test Well Poplar 02 2010 24
- 26. August 28, 2016 November 21, 2016 Test Well 1 Test Well 2 Test Well 1 Test Well 2 MDL Report ing Limit (mg/L) Trichloroethene 280 ND 300 ND 1.1 5 cis-1,2-Dichloroethene 140 ND 160 ND 1.5 5 1,1-Dichloroethane 7.9 0.64 9 0.58 0.12 0.5 1,1-Dichloroethene 7.6 ND 6.8 ND 0.09 0.5 trans-1,2-Dichloroethene 1.7 ND 3.1 ND 0.13 0.5 Tetrachloroethene 0.85 ND 0.88 ND 0.12 0.5 Vinyl chloride 0.54 ND 0.77 ND 0.17 0.5 Chloroform 0.38 ND ND ND 0.13 0.5 Up flow Down flow Up flow Down flow Upflow of trees Well 1 vs. Downflow of trees Well 2 26
- 27. 6 ‘ 10 ‘ Next Steps in Consideration Pre-planning Phase Connect the three test plots, Inoculate all poplar trees, Consider other sites 27
- 28. Thank you Acknowledge NASA, ERT, UW, PPCU and Edenspace For more information Contact John Freeman [email protected] 970-420-5164 Intrinsyx Websites http://research.intrinsyx.com www.intrinsyx.com 28
- 29. Common Sequential Reductive Dechlorination Pathways: The most common anaerobic dechlorination pathway is the degradation of tetrachloroethene (PCE) to ethene. In the sequential transformation of the chlorinated ethenes shown below, chlorine is replaced using hydrogen as an electron donor. 29
- 30. 1. The facultative anaerobes Enterobacter sp. strain MS-1 and Pantoea agglomerans have so far been reported to reductively dechlorinate perchloroethylene (PCE), thereby converting it to dichloroethene (DCE). This occurs only under strictly anoxic conditions (14,29) and likely through action of a monooxygenase gene. 2. Attempts to amplify monooxygenase genes using conserved PCR primer sets were unsuccessful, suggesting that PDN3 uses a not-yet-discovered pathway for TCE degradation. 3. Since PDN3 grew to a higher optical density in medium containing TCE than in the same medium without TCE, these results suggest that PDN3 used TCE as an additional carbon source. Applied and Environmental Microbiology 2012, 78(9): p. 3504–3507 30