| Metabolic Biomarkers for Monitoring in Situ Anaerobic Hydrocarbon Degradation Lily Y. Young and Craig D. Phelps Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA Abstract
During the past 15 years researchers have made great strides in understanding the metabolism of hydrocarbons by anaerobic bacteria. Organisms capable of utilizing benzene, toluene, ethylbenzene, xylenes, alkanes, and polycyclic aromatic hydrocarbons have been isolated and described. In addition, the mechanisms of degradation for these compounds have been elucidated. This basic research has led to the development of methods for detecting in situ biodegradation of petroleum-related pollutants in anoxic groundwater. Knowledge of the metabolic pathways used by anaerobic bacteria to break down hydrocarbons has allowed us to identify unique intermediate compounds that can be used as biomarkers for in situ activity. One of these unique intermediates is 2-methylbenzylsuccinate, the product of fumarate addition to o-xylene by the enzyme responsible for toluene utilization. We have carried out laboratory studies to show that this compound can be used as a reliable indicator of anaerobic toluene degradation. Field studies confirmed that the biomarker is detectable in field samples and its distribution corresponds to areas where active biodegradation is predicted. For naphthalene, three biomarkers were identified [2-naphthoic acid (2-NA) , tetrahydro-2-NA, and hexahydro-2-NA] that can be used in the field to identify areas of active in situ degradation. Key words: anaerobic, biomarker, bioremediation, hydrocarbons, naphthalene, petroleum, toluene. Environ Health Perspect 113:62-67 (2005) . doi:10.1289/ehp.6940 available via http://dx.doi.org/ [Online 8 December 2004]
This article is based on a presentation at the conference "Bioremediation and Biodegradation: Current Advances in Reducing Toxicity, Exposure and Environmental Consequences" (http://www-apps.niehs.nih.gov/sbrp/bioremediation.html) held 9-12 June 2002 in Pacific Grove, California, and sponsored by the National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research Program. The overall focus of this conference was on exploring the research interfaces of toxicity reduction, exposure assessment, and evaluation of environmental consequences in the context of using state-of-the-art approaches to bioremediation and biodegradation. The Superfund Basic Research Program has a legacy of supporting research conferences designed to integrate the broad spectrum of disciplines related to hazardous substances. Address correspondence to C.D. Phelps, Biotechnology Center for Agriculture and the Environment, 59 Dudley Rd., Foran Hall, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901 USA. Telephone: (732) 932-8165, ext. 314. Fax: (732) 932-0312. E-mail: phelps@envsci.rutgers.edu We thank J. Battistelli, P. Ceraulo, P. Evans, C-M. So, J. Weiss, and X. Zhang for their contributions to this work. Research was supported by grants from the Office of Naval Research, the Defense Advanced Research Projects Agency, and the National Science Foundation. The authors declare they have no competing financial interests. Received 30 December 2003 ; accepted 19 May 2004.
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