Carbon isotope fractionation during anaerobic degradation of methyl tert-butyl ether under sulfate-reducing and methanogenic conditions

Piyapawn Somsamak, Hans H. Richnow, Max Haggblom

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ε) estimated for each enrichment were almost identical (-13.4‰ to -14.6‰; r2 = 0.89 to 0.99). A ε value of -14.4‰ ± 0.7‰ was obtained from regression analysis (r2 = 0.97, n = 55, 95% confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation.

Original languageEnglish (US)
Pages (from-to)1157-1163
Number of pages7
JournalApplied and environmental microbiology
Volume72
Issue number2
DOIs
StatePublished - Feb 1 2006

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Carbon Isotopes
isotope fractionation
MTBE
Sulfates
carbon isotope
ethers
sulfates
fractionation
sulfate
degradation
carbon
electrons
Electrons
electron
methyl tert-butyl ether
Physical Phenomena
octane
Water Resources
Gasoline
enrichment culture

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

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abstract = "Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ε) estimated for each enrichment were almost identical (-13.4‰ to -14.6‰; r2 = 0.89 to 0.99). A ε value of -14.4‰ ± 0.7‰ was obtained from regression analysis (r2 = 0.97, n = 55, 95{\%} confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation.",
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Carbon isotope fractionation during anaerobic degradation of methyl tert-butyl ether under sulfate-reducing and methanogenic conditions. / Somsamak, Piyapawn; Richnow, Hans H.; Haggblom, Max.

In: Applied and environmental microbiology, Vol. 72, No. 2, 01.02.2006, p. 1157-1163.

Research output: Contribution to journalArticle

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