Anaerobic ethylene glycol degradation by microorganisms in poplar and willow rhizospheres
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Although aerobic degradation of ethylene glycol is well documented, only anaerobic biodegradation via methanogenesis or fermentation has been clearly shown. Enhanced ethylene glycol degradation has been demonstrated by microorganisms in the rhizosphere of shallow-rooted plants such as alfalfa and grasses where conditions may be aerobic, but has not been demonstrated in the deeper rhizosphere of poplar or willow trees where conditions are more likely to be anaerobic. This study evaluated ethylene glycol degradation under nitrate-, and sulphate-reducing conditions by microorganisms from the rhizosphere of poplar and willow trees planted in the path of a groundwater plume containing up to 1.9 mol l−1 (120 g l−1) ethylene glycol and, the effect of fertilizer addition when nitrate or sulphate was provided as a terminal electron acceptor (TEA). Microorganisms in these rhizosphere soils degraded ethylene glycol using nitrate or sulphate as TEAs at close to the theoretical stoichiometric amounts required for mineralization. Although the added nitrate or sulphate was primarily used as TEA, TEAs naturally present in the soil or CO2 produced from ethylene glycol degradation were also used, demonstrating multiple TEA usage. Anaerobic degradation produced acetaldehyde, less acetic acid, and more ethanol than under aerobic conditions. Although aerobic degradation rates were faster, close to 100% disappearance was eventually achieved anaerobically. Degradation rates under nitrate-reducing conditions were enhanced upon fertilizer addition to achieve rates similar to aerobic degradation with up to 19.3 mmol (1.20 g) of ethylene glycol degradation l−1 day−1 in poplar soils. This is the first study to demonstrate that microorganisms in the rhizosphere of deep rooted trees like willow and poplar can anaerobically degrade ethylene glycol. Since anaerobic biodegradation may significantly contribute to the phytoremediation of ethylene glycol in the deeper subsurface, the need for “pump and treat” or an aerobic treatment would be eliminated, hence reducing the cost of treatment.
KeywordsEthylene glycol Anaerobic Bioremediation Poplar Willow Nitrate Sulphate
The authors acknowledge the financial support of Malroz Engineering, Kingston, ON, and Ontario Centers of Excellence, Centre of Excellence for Earth and Environmental Technologies and Queen’s University for financial support to D. Carnegie.
- Alexander M (1994) Biodegradation and bioremediation. Academic Press, New YorkGoogle Scholar
- Commission of the European Communities (2004) Case No 3467—DOW Chemicals. Office for Official Publications of the European CommunitiesGoogle Scholar
- Cookson JT (1995) Bioremediation engineering design and application. McGraw-Hill, New York, pp 474–475Google Scholar
- Cote R, Gherna R (1994) Nutrition and media. In: Gerhardt P, Murray RGE, Wood WA, Krieg NR (eds) Methods for general and molecular bacteriology. American Society for Microbiology, Washington, DC, pp 155–178Google Scholar
- McGahey C, Bouwer EJ (1992) Biodegradation of ethylene glycol in simulated sub-surface environments. Water Sci Technol 26:41–49Google Scholar
- Rice P, Anderson T, Coats J (1997) Evaluation of the use of vegetation for reducing the environmental impact of deicing agents. In: Kruger F, Anderson T, Coats J (eds) Phytoremediation of soil and water contaminants. ACS Symposium Series No. 664, American Chemical Society, Washington, DC, pp 162–176Google Scholar
- Strab A, Schink B (1986) Fermentation of polyethylene glycol via acetaldehyde in Pelobacter venetianus. Appl Microbiol Biotechnol 25:37–42Google Scholar