Characteristic Hydrogen Concentrations for Various Redox Processes in Batch Study

Lu, Xiaofan; Tao, Shu; Bosma, Tom N. P.; Gerritse, Jan

doi:10.1081/ese-100106254

Cited by 46 publications

(42 citation statements)

References 21 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%

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%

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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“…This is in agreement with the findings of Amos et al (1), who showed that Dehalococcoides strains respond differently to oxygen exposure: strains with VCreductase genes are more susceptible to oxygen inhibition than others (1). Lu et al (13) showed that for dechlorination on April 27, 2019 by guest http://aem.asm.org/ of VC, the hydrogen threshold values were in the range of methanogenesis (2 to 24 nM), whereas these threshold values for PCE and TCE were in the range of denitrification and ferric iron reduction (0.1 to 0.4 nM) (13). Unfortunately, hydrogen data were only available for locations A, I, and J and could therefore not be included in the RDA.…”

Section: Discussionmentioning

confidence: 99%

Correlation of Dehalococcoides 16S rRNA and Chloroethene-Reductive Dehalogenase Genes with Geochemical Conditions in Chloroethene-Contaminated Groundwater

Zaan

Hannes

Hoekstra

et al. 2010

Appl Environ Microbiol

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Quantitative analysis of genes that code for Dehalococcoides 16S rRNA and chloroethene-reductive dehalogenases TceA, VcrA, and BvcA was done on groundwater sampled from 150 monitoring wells spread over 11 chlorinated ethene polluted European locations. Redundancy analysis was used to relate molecular data to geochemical conditions. Dehalococcoides 16S rRNA-and vinyl chloride (VC)-reductase genes were present at all tested locations in concentrations up to 10 6 gene copies per ml of groundwater. However, differences between and also within locations were observed. Variation in Dehalococcoides 16S rRNA gene copy numbers were most strongly correlated to dissolved organic carbon concentration in groundwater and to conditions appropriate for biodegradation of chlorinated ethenes (U.S. Environmental Protection Agency score). In contrast, vcrA gene copy numbers correlated most significantly to VC and chlorinated ethene concentrations. Interestingly, bvcA and especially tceA were more correlated with oxidizing conditions. In groundwater microcosms, dechlorination of 1 mM VC was correlated to an increase of vcrA and/or bvcA gene copies by 2 to 4 orders of magnitude. Interestingly, in 34% of the monitoring wells and in 40% of the active microcosms, the amount of individual VC-reductase gene copies exceeded that of Dehalococcoides 16S rRNA gene copies. It is concluded that the geographical distribution of the genes was not homogeneous, depending on the geochemical conditions, whereby tceA and bvcA correlated to more oxidized conditions than Dehalococcoides 16S rRNA and vcrA. Because the variation in VC-reductase gene numbers was not directly correlated to variation in Dehalococcoides spp., VC-reductase genes are better monitoring parameters for VC dechlorination capacity than Dehalococcoides spp.

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“…pose strict nutrient requirements in the dechlorination reaction (He et al 2007;Maymo-Gatell et al 1997). In addition, cis-DCE dechlorination by Dehalococcoides has been reported to require higher levels of H 2 than those required for TCE degradation to cis-DCE (Lu et al 2001). …”

Section: Analytical Methods and Data Analysis Tcementioning

confidence: 99%

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

Haest

Philips

Springael

et al. 2011

Journal of Contaminant Hydrology

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The dechlorination rate in a flow-through porous matrix can be described by the species specific dechlorination rate observed in a liquid batch unless mass transport limitations prevail. This hypothesis was examined by comparing dechlorination rates in liquid batch with that in column experiments at various flow rates (3 -9 -12 cm d -1 ). Columns were loaded with an inoculated sand and eluted with a medium containing 1 mM trichloroethene (TCE) for 247 days. Dechlorination in the column treatments increased with decreasing flow rate, illustrating the effect of the longer residence time. Zero th order TCE or cis-DCE degradation rates were 4-7 fold larger in columns than in corresponding batch systems which could be explained by the higher measured Geobacter and Dehalococcoides numbers per unit pore volume in the columns. The microbial numbers also explained the variability in dechlorination rate among flow rate treatments marked by a large elution of the dechlorinating species' yield as flow increased. Stop flow events did not reveal mass transport limitations for dechlorination. We conclude that flow rate effects on reactive transport of TCE in this coarse sand are explained by residence time and by microbial transport and that mass transport limitations in this porous matrix are limited.

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Characteristic Hydrogen Concentrations for Various Redox Processes in Batch Study

Cited by 46 publications

References 21 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

Correlation of Dehalococcoides 16S rRNA and Chloroethene-Reductive Dehalogenase Genes with Geochemical Conditions in Chloroethene-Contaminated Groundwater

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

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