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Assessing in situ rates of anaerobic hydrocarbon bioremediation.

ABSTRACT: Identifying metabolites associated with anaerobic hydrocarbon biodegradation is a reliable way to garner evidence for the intrinsic bioremediation of problem contaminants. While such metabolites have been detected at numerous sites, the in situ rates of anaerobic hydrocarbon decay remain largely unknown. Yet, realistic rate information is critical for predicting how long individual contaminants will persist and remain environmental threats. Here, single-well push-pull tests were conducted at two fuel-contaminated aquifers to determine the in situ biotransformation rates of a suite of hydrocarbons added as deuterated surrogates, including toluene-d(8), o-xylene-d(10), m-xylene-d(10), ethylbenzene-d(5) (or -d(10)), 1, 2, 4-trimethylbenzene-d(12), 1, 3, 5-trimethylbenzene-d(12), methylcyclohexane-d(14) and n-hexane-d(14). The formation of deuterated fumarate addition and downstream metabolites was quantified and found to be somewhat variable among wells in each aquifer, but generally within an order of magnitude. Deuterated metabolites formed in one aquifer at rates that ranged from 3 to 50 µg l(-1) day(-1), while the comparable rates at another aquifer were slower and ranged from 0.03 to 15 µg l(-1) day(-1). An important observation was that the deuterated hydrocarbon surrogates were metabolized in situ within hours or days at both sites, in contrast to many laboratory findings suggesting that long lag periods of weeks to months before the onset of anaerobic biodegradation are typical. It seems clear that highly reduced conditions are not detrimental to the intrinsic bioremediation of fuel-contaminated aquifers.

SUBMITTER: Gieg LM

PROVIDER: S-EPMC3815842 | biostudies-other | 2009 Mar

REPOSITORIES: biostudies-other

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Assessing in situ rates of anaerobic hydrocarbon bioremediation.

Gieg Lisa M LM Alumbaugh Robert E RE Field Jennifer J Jones Jesse J Istok Jonathon D JD Suflita Joseph M JM

Microbial biotechnology 20090301 2

Identifying metabolites associated with anaerobic hydrocarbon biodegradation is a reliable way to garner evidence for the intrinsic bioremediation of problem contaminants. While such metabolites have been detected at numerous sites, the in situ rates of anaerobic hydrocarbon decay remain largely unknown. Yet, realistic rate information is critical for predicting how long individual contaminants will persist and remain environmental threats. Here, single-well push-pull tests were conducted at two ...[more]

PMID: 21261916

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Project description:A culture-independent molecular phylogenetic approach was used to survey constituents of microbial communities associated with an aquifer contaminated with hydrocarbons (mainly jet fuel) and chlorinated solvents undergoing intrinsic bioremediation. Samples were obtained from three redox zones: methanogenic, methanogenic-sulfate reducing, and iron or sulfate reducing. Small-subunit rRNA genes were amplified directly from aquifer material DNA by PCR with universally conserved or Bacteria- or Archaea-specific primers and were cloned. A total of 812 clones were screened by restriction fragment length polymorphisms (RFLP), approximately 50% of which were unique. All RFLP types that occurred more than once in the libraries, as well as many of the unique types, were sequenced. A total of 104 (94 bacterial and 10 archaeal) sequence types were determined. Of the 94 bacterial sequence types, 10 have no phylogenetic association with known taxonomic divisions and are phylogenetically grouped in six novel division level groups (candidate divisions WS1 to WS6); 21 belong to four recently described candidate divisions with no cultivated representatives (OP5, OP8, OP10, and OP11); and 63 are phylogenetically associated with 10 well-recognized divisions. The physiology of two particularly abundant sequence types obtained from the methanogenic zone could be inferred from their phylogenetic association with groups of microorganisms with a consistent phenotype. One of these sequence types is associated with the genus Syntrophus; Syntrophus spp. produce energy from the anaerobic oxidation of organic acids, with the production of acetate and hydrogen. The organism represented by the other sequence type is closely related to Methanosaeta spp., which are known to be capable of energy generation only through aceticlastic methanogenesis. We hypothesize, therefore, that the terminal step of hydrocarbon degradation in the methanogenic zone of the aquifer is aceticlastic methanogenesis and that the microorganisms represented by these two sequence types occur in syntrophic association.

Dataset Information

Assessing in situ rates of anaerobic hydrocarbon bioremediation.

Publications

Assessing in situ rates of anaerobic hydrocarbon bioremediation.

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