Hydrogen threshold concentrations in pure cultures of halorespiring bacteria and at a site polluted with chlorinated ethenes

Luijten, M.L.G.C.; Roelofsen, Wim; Langenhoff, Alette; Schraa, G.; Stams, A.J.M.

doi:10.1111/j.1462-2920.2004.00608.x

Cited by 54 publications

(41 citation statements)

References 25 publications

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“…This finding is consistent with previously published H 2 thresholds for dechlorination by Dehalococcoides-containing communities (10,41) and falls in the same range as the thresholds for sulfate reduction (46). Other dechlorinating isolates have been reported to have minimum H 2 thresholds of around 0.04 to 0.3 nM (11,46,47). In previous studies of S. wolfei growing with H 2 -oxidizing hydrogenotrophic methanogens, sulfate reducers, and nitrate reducers, the estimated energy available for S. wolfei (51).…”

Section: Discussionsupporting

confidence: 82%

“…Therefore, the minimum H 2 threshold for strain 195 cells is likely not based on thermodynamics but is rather based upon other factors such as enzyme binding affinity and specificity (45). This finding is consistent with previously published H 2 thresholds for dechlorination by Dehalococcoides-containing communities (10,41) and falls in the same range as the thresholds for sulfate reduction (46). Other dechlorinating isolates have been reported to have minimum H 2 thresholds of around 0.04 to 0.3 nM (11,46,47).…”

Section: Discussionsupporting

confidence: 82%

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Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

Mao

Stenuit

Polasko

et al. 2015

Appl Environ Microbiol

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bDehalococcoides mccartyi 195 (strain 195) and Syntrophomonas wolfei were grown in a sustainable syntrophic coculture using butyrate as an electron donor and carbon source and trichloroethene (TCE) as an electron acceptor. The maximum dechlorination rate (9.9 ؎ 0.1 mol day ؊1 ) and cell yield [(1.1 ؎ 0.3) ؋ 10 8 cells mol ؊1 Cl ؊ ] of strain 195 maintained in coculture were, respectively, 2.6 and 1.6 times higher than those measured in the pure culture. The strain 195 cell concentration was about 16 times higher than that of S. wolfei in the coculture. Aqueous H 2 concentrations ranged from 24 to 180 nM during dechlorination and increased to 350 ؎ 20 nM when TCE was depleted, resulting in cessation of butyrate fermentation by S. wolfei with a theoretical Gibbs free energy of ؊13.7 ؎ 0.2 kJ mol ؊1 . Carbon monoxide in the coculture was around 0.06 mol per bottle, which was lower than that observed for strain 195 in isolation. The minimum H 2 threshold value for TCE dechlorination by strain 195 in the coculture was 0.6 ؎ 0.1 nM. Cell aggregates during syntrophic growth were observed by scanning electron microscopy. The interspecies distances to achieve H 2 fluxes required to support the measured dechlorination rates were predicted using Fick's law and demonstrated the need for aggregation. Filamentous appendages and extracellular polymeric substance (EPS)-like structures were present in the intercellular spaces. The transcriptome of strain 195 during exponential growth in the coculture indicated increased ATP-binding cassette transporter activities compared to the pure culture, while the membrane-bound energy metabolism related genes were expressed at stable levels. Groundwater contamination by trichloroethene (TCE), a potential human carcinogen, poses a serious threat to human health and can lead to the generation of vinyl chloride (VC), which is a known human carcinogen (1). Strains of Dehalococcoides mccartyi are the only known bacteria that can completely degrade TCE to the benign end product ethene. Biostimulation of indigenous Dehalococcoides spp. and bioaugmentation using Dehalococcoides-containing cultures are recognized as the most reliable in situ bioremediation technologies resulting in the complete dechlorination of TCE to ethene (2). However, the mechanisms that regulate the activity of D. mccartyi within natural ecosystems and shape its functional robustness in disturbed environments are poorly understood due to multiscale microbial community complexity and heterogeneity of biogeochemical processes involved in the sequential degradation (3, 4). D. mccartyi exhibits specific restrictive metabolic requirements for a variety of exogenous compounds, such as hydrogen, acetate, corrinoids, biotin, and thiamine, which can be supplied by other microbial genera through a complex metabolic network (1,(5)(6)(7)(8). Therefore, the growth of D. mccartyi is more robust within functionally diverse microbial communities that are deterministically assembled than in pure cultures (5,8,9). Previous studies have shown t...

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Section: Discussionsupporting

confidence: 82%

Section: Discussionsupporting

confidence: 82%

Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

Mao

Stenuit

Polasko

et al. 2015

Appl Environ Microbiol

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“…In contrast, sulfate reduction (process 7 in Fig. 1) and iron reduction often occur concomitantly with dechlorination and thus in the model these electron acceptors compete with dechlorinators for H 2 [13,58]. Sulfate reduction rate is described by: …”

Section: Numerical Modelmentioning

confidence: 99%

Biological reduction of chlorinated solvents: Batch-scale geochemical modeling

Kouznetsova

Mao

Robinson

et al. 2010

Advances in Water Resources

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Simulation of biodegradation of chlorinated solvents in dense non-aqueous phase liquid (DNAPL) source zones requires a model that accounts for the complexity of processes involved and that is consistent with available laboratory studies. This paper describes such a comprehensive modeling framework that includes microbially mediated degradation processes, microbial population growth and decay, geochemical reactions, as well as interphase mass transfer processes such as DNAPL dissolution, gas formation and mineral precipitation/dissolution. All these processes can be in equilibrium or kinetically controlled. A batch modeling example was presented where the degradation of trichloroethene (TCE) and its byproducts and concomitant reactions (e.g., electron donor fermentation, sulfate reduction, pH buffering by calcite dissolution) were simulated. Local and global sensitivity analysis techniques were applied to delineate the dominant model parameters and processes. Sensitivity analysis indicated that accurate values for parameters related to dichloroethene (DCE) and vinyl chloride (VC) degradation (i.e., DCE and VC maximum utilization rates, yield due to DCE utilization, decay rate for DCE/VC dechlorinators) are important for prediction of the overall dechlorination time. These parameters influence the maximum growth rate of the DCE and VC dechlorinating microorganisms and, thus, the time required for a small initial population to reach a sufficient concentration to significantly affect the overall rate of dechlorination. Self-inhibition of chlorinated ethenes at high concentrations and natural buffering provided by the sediment were also shown to significantly influence the dechlorination time. Furthermore, the analysis indicated that the rates of the competing, nonchlorinated electron-accepting processes relative to the dechlorination kinetics also affect the overall dechlorination time. Results demonstrated that the model developed is a flexible research tool that is able to provide valuable insight into the fundamental processes and their complex interactions during bioremediation of chlorinated ethenes in DNAPL source zones.

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“…Different methods have been proposed to evaluate the occurrence of complete reductive dechlorination of chlorinated ethenes including: 1) characterization of geochemical conditions (availability of electron donors such as H 2 , Luijten et al, 2004; assessment of redox conditions, Witt et al, 2002;Lu et al, 2006), 2) characterization of parent and daughter product patterns (Witt et al, 2002) and 3) assessment of the presence and activity of key organisms such as Dehalococcoides (Fennell et al, 2001;Hendrickson et al, 2002;Müller et al, 2004;Duhamel and Edwards, 2006;Rahm and Richardson, 2008;Imfeld et al, 2008;Lee et al, 2008). While geochemical conditions and the presence of certain organisms can indicate whether the conditions are favorable for reductive dechlor-ination, these parameters usually do not provide information about the degree of transformation.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the fate of chlorinated ethenes in streambed sediments by combining stable isotope, geochemical and microbial methods

Abe

Aravena

Zopfi

et al. 2009

Journal of Contaminant Hydrology

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a b s t r a c tThe occurrence of chlorinated ethene transformation in a streambed was investigated using concentration and carbon isotope data from water samples taken at different locations and depths within a 15 × 25 m study area across which a tetrachloroethene (PCE) plume discharges. Furthermore, it was evaluated how the degree of transformation is related to groundwater discharge rates, redox conditions, solid organic matter content (SOM) and microbial factors. Groundwater discharge rates were quantified based on streambed temperatures, and redox conditions using concentrations of dissolved redox-sensitive species. The degree of chlorinated ethene transformation was highly variable in space from no transformation to transformation beyond ethene. Complete reductive dechlorination to ethane and ethene occurred at locations with at least sulfate-reducing conditions and with a residence time in the samples streambed zone (80 cm depth) of at least 10 days. Among these locations, Dehalococcoides was detected using a PCR method where SOM contents were N 2% w/w and where transformation proceeded beyond ethene. However, it was not detected at locations with low SOM, which may cause an insufficient H 2 supply to sustain a detectably dense Dehalococcoides population. Additionally, it is possible that other organisms are responsible for the biodegradation. A microcosm study with streambed sediments demonstrated the potential of VC oxidation throughout the site even at locations without a pre-exposure to VC, consistent with the detection of the epoxyalkane:coenzyme M transferase (EaCoMT) gene involved in the degradation of chlorinated ethenes via epoxidation. In contrast, no aerobic transformation of cDCE in microcosms over a period of 1.5 years was observed. In summary, the study demonstrated that carbon isotope analysis is a sensitive tool to identify the degree of chlorinated ethene transformation even in hydrologically and geochemically complex streambed systems. In addition, it was observed that the degree of transformation is related to redox conditions, which in turn depend on groundwater discharge rates.

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Hydrogen threshold concentrations in pure cultures of halorespiring bacteria and at a site polluted with chlorinated ethenes

Cited by 54 publications

References 25 publications

Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

Biological reduction of chlorinated solvents: Batch-scale geochemical modeling

Evaluating the fate of chlorinated ethenes in streambed sediments by combining stable isotope, geochemical and microbial methods

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