Effects of sulfate on anaerobic chloroethene degradation by an enriched culture under transient and steady-state hydrogen supply

Heimann, Axel Colin; Friis, Anne Kirketerp; Jakobsen, Rasmus

doi:10.1016/j.watres.2005.06.029

Cited by 73 publications

(55 citation statements)

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“…This enrichment culture was originally derived from trichloroethylene-contaminated soil and groundwater and contains Dehalococcoides bacteria that are able to grow on vinyl chloride as an electron acceptor (16,17). All incubations were performed in sulfate-free medium as described by Heimann et al (25) (major components were phosphate, ammonium, calcium, and magnesium salts; trace metals; vitamins; bicarbonate; iron sulfide; no yeast extract). Experiments were conducted with both a fresh KB-1 culture (used directly after shipping) and a culture that had been used in different experimental setups for a total of 315 days prior to the experiments reported here.…”

Section: Methodsmentioning

confidence: 99%

Methanosarcina spp. Drive Vinyl Chloride Dechlorination via Interspecies Hydrogen Transfer

Heimann

Batstone

Jakobsen

2006

Appl Environ Microbiol

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Two highly enriched cultures containing Dehalococcoides spp. were used to study the effect of aceticlastic methanogens on reductive vinyl chloride (VC) dechlorination. In terms of aceticlastic methanogens, one culture was dominated by Methanosaeta, while the other culture was dominated by Methanosarcina, as determined by fluorescence in situ hybridization. Cultures amended with 2-bromoethanesulfonate (BES), an efficient inhibitor of methanogens, exhibited slow VC dechlorination when grown on acetate and VC. Methanogenic cultures dominated by Methanosaeta had no impact on dechlorination rates, compared to BES-amended controls. In contrast, methanogenic cultures dominated by Methanosarcina displayed up to sevenfold-higher rates of VC dechlorination than their BES-amended counterparts. Methanosarcina-dominated cultures converted a higher percentage of [2-14 C]acetate to 14 CO 2 when concomitant VC dechlorination took place, compared to nondechlorinating controls. Respiratory indices increased from 0.12 in nondechlorinating cultures to 0.51 in actively dechlorinating cultures. During VC dechlorination, aqueous hydrogen (H 2 ) concentrations dropped to 0.3 to 0.5 nM. However, upon complete VC consumption, H 2 levels increased by a factor of 10 to 100, indicating active hydrogen production from acetate oxidation. This process was thermodynamically favorable by means of the extremely low H 2 levels during dechlorination. VC degradation in nonmethanogenic cultures was not inhibited by BES but was limited by the availability of H 2 as electron donor, in cultures both with and without BES. These findings all indicate that Methanosarcina (but not Methanosaeta), while cleaving acetate to methane, simultaneously oxidizes acetate to CO 2 plus H 2 , driving hydrogenotrophic dehalorespiration of VC to ethene by Dehalococcoides.Contamination with chlorinated ethenes, an almost ubiquitous class of pollutants, presently poses a serious threat to groundwater quality in industrialized countries (1). Microbial reductive dechlorination is the major pathway of degradation and detoxification of chloroethenes under anaerobic conditions (26). Dehalorespiring bacteria (DRB; synonym, chlororespiring bacteria) are able to use the energy available from reductive dechlorination in a respiratory process (27, 28); however, sequential dechlorination may result in transient buildup of the highly toxic metabolite vinyl chloride (VC) (15,44). DRB growing with vinyl chloride as an electron acceptor are to date restricted to the Dehalococcoides group of bacteria (11,12,16,23). All known Dehalococcoides isolates require hydrogen (H 2 ) as a direct electron donor (3,23,34). However, in anaerobic substrate degradation, a considerable fraction of organic carbon is converted to methane via acetate. The latter may also be oxidized by sulfate-reducing, Fe(III)-reducing, or denitrifying bacteria (49), while known VC-dechlorinating DRB are unable to use acetate as a direct electron donor. H 2 production from acetate is an obligately syntrophic process that may...

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Section: Methodsmentioning

confidence: 99%

Methanosarcina spp. Drive Vinyl Chloride Dechlorination via Interspecies Hydrogen Transfer

Heimann

Batstone

Jakobsen

2006

Appl Environ Microbiol

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“…Heimann et al, 2005;Wei and Finneran, 2011). Several studies suggest that chlorinated ethenes and ethanes can undergo abiotic degradation through reactions with reduced iron minerals (e.g.…”

Section: Redox Conditionsmentioning

confidence: 99%

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Damgaard

Bjerg

Bælum

et al. 2013

Journal of Contaminant Hydrology

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a b s t r a c tThe degradation of chlorinated ethenes and ethanes in clay till was investigated at a contaminated site (Vadsby, Denmark) by high resolution sampling of intact cores combined with groundwater sampling. Over decades of contamination, bioactive zones with degradation of trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) to 1,2-cis-dichloroethene (cis-DCE) and 1,1-dichloroethane, respectively, had developed in most of the clay till matrix. Dehalobacter dominated over Dehalococcoides (Dhc) in the clay till matrix corresponding with stagnation of sequential dechlorination at cis-DCE. Sporadically distributed bioactive zones with partial degradation to ethene were identified in the clay till matrix (thickness from 0.10 to 0.22 m). In one sub-section profile the presence of Dhc with the vcrA gene supported the occurrence of degradation of cis-DCE and VC, and in another enriched δ 13 C for TCE, cis-DCE and VC documented degradation. Highly enriched δ 13 C for 1,1,1-TCA (25‰) and cis-DCE (−4‰) suggested the occurrence of abiotic degradation in a third sub-section profile. Due to fine scale heterogeneity the identification of active degradation zones in the clay till matrix depended on high resolution subsampling of the clay till cores. The study demonstrates that an integrated approach combining chemical analysis, molecular microbial tools and compound specific isotope analysis (CSIA) was required in order to document biotic and abiotic degradations in the clay till system.

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“…In addition, some conflicting results due to sulfate addition, ranging from enhanced dechlorination (27,29,30) to inhibited or incomplete dechlorination (15,27,29,31,32), as well as no observed effect on dechlorination (16,25), have been reported over the past decade. A review of published field data from TCE-contaminated sites with sulfate concentrations ranging from 39 to 4,800 mg liter Ϫ1 reported the overall trend that as sulfate concentrations increased, dechlorination reactions became incomplete or delayed (26).…”

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confidence: 99%

“…A review of published field data from TCE-contaminated sites with sulfate concentrations ranging from 39 to 4,800 mg liter Ϫ1 reported the overall trend that as sulfate concentrations increased, dechlorination reactions became incomplete or delayed (26). In addition, among these previous studies, there have only been a few that used microbial communities with the confirmed presence of D. mccartyi (15,28,30,32,33) and cellular quantification has been lacking. Further work is needed to clarify the significance of sulfate concentrations on reductive dechlorination under electron donor/acceptor-limiting conditions.…”

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confidence: 99%

Effects of Sulfate Reduction on Trichloroethene Dechlorination by Dehalococcoides-Containing Microbial Communities

Mao

Polasko

Alvarez‐Cohen

2017

Appl Environ Microbiol

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In order to elucidate interactions between sulfate reduction and dechlorination, we systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. Sulfate (up to 5 mM) did not inhibit the growth or metabolism of pure cultures of the dechlorinator Dehalococcoides mccartyi 195, the sulfate reducer Desulfovibrio vulgaris Hildenborough, or the syntroph Syntrophomonas wolfei. In contrast, sulfide at 5 mM exhibited inhibitory effects on growth of the sulfate reducer and the syntroph, as well as on both dechlorination and growth rates of D. mccartyi. Transcriptomic analysis of D. mccartyi 195 revealed that genes encoding ATP synthase, biosynthesis, and Hym hydrogenase were downregulated during sulfide inhibition, whereas genes encoding metal-containing enzymes involved in energy metabolism were upregulated even though the activity of those enzymes (hydrogenases) was inhibited. When the electron acceptor (trichloroethene) was limiting and an electron donor (lactate) was provided in excess to cocultures and enrichments, high sulfate concentrations (5 mM) inhibited reductive dechlorination due to the toxicity of generated sulfide. The initial cell ratio of sulfate reducers to D. mccartyi (1:3, 1:1, or 3:1) did not affect the dechlorination performance in the presence of sulfate (2 and 5 mM). In contrast, under electron donor limitation, dechlorination was not affected by sulfate amendments due to low sulfide production, demonstrating that D. mccartyi can function effectively in anaerobic microbial communities containing moderate sulfate concentrations (5 mM), likely due to its ability to outcompete other hydrogen-consuming bacteria and archaea.IMPORTANCE Sulfate is common in subsurface environments and has been reported as a cocontaminant with chlorinated solvents at various concentrations. Inconsistent results for the effects of sulfate inhibition on the performance of dechlorination enrichment cultures have been reported in the literature. These inconsistent findings make it difficult to understand potential mechanisms of sulfate inhibition and complicate the interpretation of bioremediation field data. In order to elucidate interactions between sulfate reduction and reductive dechlorination, this study systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. This study provides a more fundamental understanding of the competition mechanisms between reductive dechlorination by Dehalococcoides mccartyi and sulfate reduction during the bioremediation process. It also provides insights on the significance of sulfate concentrations on reductive dechlorination under electron donor/acceptor-limiting conditions during in situ bioremediation applications. For example, at a trichloroethene-contaminated site with a high sulfate concentration, proper...

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Effects of sulfate on anaerobic chloroethene degradation by an enriched culture under transient and steady-state hydrogen supply

Cited by 73 publications

References 26 publications

Methanosarcina spp. Drive Vinyl Chloride Dechlorination via Interspecies Hydrogen Transfer

Methanosarcina spp. Drive Vinyl Chloride Dechlorination via Interspecies Hydrogen Transfer

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Effects of Sulfate Reduction on Trichloroethene Dechlorination by Dehalococcoides-Containing Microbial Communities

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