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Andreas Tiehm - One of the best experts on this subject based on the ideXlab platform.
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Aerobic metabolic triChloroethene biodegradation under field-relevant conditions.
Water research, 2018Co-Authors: Sarah Gaza, Kathrin R. Schmidt, Michael Heidinger, Pascal Weigold, Andreas TiehmAbstract:Abstract Chloroethenes belong to the most widely distributed groundwater contaminants. Since 2014, it has been known that triChloroethene (TCE) can be degraded aerobically and metabolically as growth substrate by a mixed bacterial enrichment culture (named SF culture). In this study, the degradation capabilities under a range of field-relevant conditions were investigated in fixed-bed reactors as well as in batch experiments. Aerobic metabolic TCE degradation was stable over the long term, with degradation optima at 22 °C and pH 7. Degradation of up to 400 μM TCE was observed. The longest starvation period after which degradation of TCE was regained was 112 days. The possible co-contaminants perChloroethene, trans-1,2-diChloroethene, and cis-1,2-diChloroethene did not inhibit TCE degradation, even though they were not degraded themselves. The presence of equimolar amounts of 1,1-diChloroethene and vinyl chloride inhibited TCE degradation. Experiments with groundwater from different Chloroethene-contaminated field sites proved the potential of the SF culture for bioaugmentation. Thus, aerobic metabolic TCE degradation should be considered as a promising method for the bioremediation of field sites with TCE as the main contaminant.
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Robustness of an aerobic metabolically vinyl chloride degrading bacterial enrichment culture
Water science and technology : a journal of the International Association on Water Pollution Research, 2011Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Svenja T. Lohner, Andreas TiehmAbstract:Degradation of the lower chlorinated ethenes is crucial to the application of natural attenuation or in situ bioremediation on chlorinated ethene contaminated sites. Recently, within mixtures of several Chloroethenes as they can occur in contaminated groundwater inhibiting effects on aerobic Chloroethene degradation have been shown. The current study demonstrated that metabolic vinyl chloride (VC) degradation by an enrichment culture originating from groundwater was not affected by an equimolar concentration (50 μM) of cis-1,2-diChloroethene (cDCE). Only cDCE concentrations at a ratio of 2.4:1 (initial cDCE to VC concentration) caused minor inhibition of VC degradation. Furthermore, the degradation of VC was not affected by the presence of trans-1,2-diChloroethene (tDCE), 1,1-diChloroethene (1,1-DCE), triChloroethene (TCE), and tetraChloroethene (PCE) in equimolar concentrations (50 μM). Only cDCE and tDCE were cometabolically degraded in small amounts. The VC-degrading culture demonstrated a broad pH tolerance from 5 to 9 with an optimum between 6 and 7. Results also showed that the culture could degrade VC concentrations up to 1,800 μM (110 mg/L).
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Sequential anaerobic/aerobic biodegradation of Chloroethenes--aspects of field application.
Current opinion in biotechnology, 2011Co-Authors: Andreas Tiehm, Kathrin R. SchmidtAbstract:Because of a range of different industrial activities, sites contaminated with Chloroethenes are a world-wide problem. Chloroethenes can be biodegraded by reductive dechlorination under anaerobic conditions as well as by oxidation under aerobic conditions. The tendency of Chloroethenes to undergo reductive dechlorination decreases with a decreasing number of chlorine substituents, whereas with less chlorine substituents Chloroethenes more easily undergo oxidative degradation. There is currently a growing interest in aerobic metabolic degradation of Chloroethenes, which demonstrates advantages compared to cometabolic degradation pathways. Sequential anaerobic/aerobic biodegradation can overcome the disadvantages of reductive dechlorination and leads to complete mineralization of the chlorinated pollutants. This approach shows promise for site remediation in natural settings and in engineered systems.
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inhibition of aerobic metabolic cis 1 2 di Chloroethene biodegradation by other Chloroethenes
Water Research, 2010Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Andreas TiehmAbstract:Abstract The presence of other Chloroethenes influences aerobic metabolic biodegradation of cis-1,2-diChloroethene (cDCE). A new metabolically cDCE degrading enrichment culture was identified as also being capable of degrading vinyl chloride (VC), but not 1,1-diChloroethene (1,1DCE), trans-1,2-diChloroethene (tDCE), triChloroethene (TCE), or tetraChloroethene (PCE). The fastest degradation of cDCE was observed in the absence of any other Chloroethene. In the presence of a second Chloroethene (40–90 μM), the rate of cDCE (60 μM) degradation decreased in the following order: cDCE (+PCE) > cDCE (+tDCE) > cDCE (+VC)> cDCE (+1,1DCE) ≈ cDCE (+TCE). With increasing concentrations of VC, ranging from 10 to 110 μM, the rate of cDCE (60 μM) degradation decreased. This study demonstrates that the inhibiting effects of Chloroethene mixtures have to be considered during laboratory studies and bioremediation approaches based on metabolic cDCE degradation.
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Inhibition of aerobic metabolic cis-1,2-di-Chloroethene biodegradation by other Chloroethenes.
Water research, 2009Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Andreas TiehmAbstract:The presence of other Chloroethenes influences aerobic metabolic biodegradation of cis-1,2-diChloroethene (cDCE). A new metabolically cDCE degrading enrichment culture was identified as also being capable of degrading vinyl chloride (VC), but not 1,1-diChloroethene (1,1DCE), trans-1,2-diChloroethene (tDCE), triChloroethene (TCE), or tetraChloroethene (PCE). The fastest degradation of cDCE was observed in the absence of any other Chloroethene. In the presence of a second Chloroethene (40-90 microM), the rate of cDCE (60 microM) degradation decreased in the following order: cDCE (+PCE) > cDCE (+tDCE) > cDCE (+VC)>cDCE (+1,1DCE) approximately cDCE (+TCE). With increasing concentrations of VC, ranging from 10 to 110 microM, the rate of cDCE (60 microM) degradation decreased. This study demonstrates that the inhibiting effects of Chloroethene mixtures have to be considered during laboratory studies and bioremediation approaches based on metabolic cDCE degradation.
Inmaculada Velasco - One of the best experts on this subject based on the ideXlab platform.
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vapour liquid equilibria for the binary mixtures 1 propanol dibromomethane or bromochloromethane or 1 2 dichloroethane or 1 bromo 2 chloroethane at t 313 15 k
The Journal of Chemical Thermodynamics, 2005Co-Authors: Vanesa Gilhernandez, Pilar Garciagimenez, Manuela Artal, Santos Otin, Inmaculada VelascoAbstract:Abstract Isothermal (vapour + liquid) equilibria (VLE) at 313.15 K have been measured for liquid 1-propanol + dibromomethane, or + bromochloromethane or + 1,2-dichloroethane or + 1-bromo-2-chloroethane mixtures. The VLE data were reduced using the Redlich–Kister equation taking into consideration the vapour phase imperfection in terms of the 2nd molar virial coefficients. The excess molar Gibbs free energies of all the studied mixtures are positive and ranging from 794 J · mol−1 for (1-propanol + bromochloromethane) and 1052 J · mol−1 for (1-propanol + 1-bromo-2-chloroethane), at x = 0.5. The experimental results are compared with modified UNIFAC predictions.
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(Vapour + liquid) equilibria for the binary mixtures (1-propanol + dibromomethane, or + bromochloromethane, or + 1,2-dichloroethane or + 1-bromo-2-chloroethane) at T = 313.15 K
The Journal of Chemical Thermodynamics, 2005Co-Authors: V. Gil-hernández, Pilar García-giménez, Manuela Artal, Santos Otin, Inmaculada VelascoAbstract:Abstract Isothermal (vapour + liquid) equilibria (VLE) at 313.15 K have been measured for liquid 1-propanol + dibromomethane, or + bromochloromethane or + 1,2-dichloroethane or + 1-bromo-2-chloroethane mixtures. The VLE data were reduced using the Redlich–Kister equation taking into consideration the vapour phase imperfection in terms of the 2nd molar virial coefficients. The excess molar Gibbs free energies of all the studied mixtures are positive and ranging from 794 J · mol−1 for (1-propanol + bromochloromethane) and 1052 J · mol−1 for (1-propanol + 1-bromo-2-chloroethane), at x = 0.5. The experimental results are compared with modified UNIFAC predictions.
Kathrin R. Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Aerobic metabolic triChloroethene biodegradation under field-relevant conditions.
Water research, 2018Co-Authors: Sarah Gaza, Kathrin R. Schmidt, Michael Heidinger, Pascal Weigold, Andreas TiehmAbstract:Abstract Chloroethenes belong to the most widely distributed groundwater contaminants. Since 2014, it has been known that triChloroethene (TCE) can be degraded aerobically and metabolically as growth substrate by a mixed bacterial enrichment culture (named SF culture). In this study, the degradation capabilities under a range of field-relevant conditions were investigated in fixed-bed reactors as well as in batch experiments. Aerobic metabolic TCE degradation was stable over the long term, with degradation optima at 22 °C and pH 7. Degradation of up to 400 μM TCE was observed. The longest starvation period after which degradation of TCE was regained was 112 days. The possible co-contaminants perChloroethene, trans-1,2-diChloroethene, and cis-1,2-diChloroethene did not inhibit TCE degradation, even though they were not degraded themselves. The presence of equimolar amounts of 1,1-diChloroethene and vinyl chloride inhibited TCE degradation. Experiments with groundwater from different Chloroethene-contaminated field sites proved the potential of the SF culture for bioaugmentation. Thus, aerobic metabolic TCE degradation should be considered as a promising method for the bioremediation of field sites with TCE as the main contaminant.
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Robustness of an aerobic metabolically vinyl chloride degrading bacterial enrichment culture
Water science and technology : a journal of the International Association on Water Pollution Research, 2011Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Svenja T. Lohner, Andreas TiehmAbstract:Degradation of the lower chlorinated ethenes is crucial to the application of natural attenuation or in situ bioremediation on chlorinated ethene contaminated sites. Recently, within mixtures of several Chloroethenes as they can occur in contaminated groundwater inhibiting effects on aerobic Chloroethene degradation have been shown. The current study demonstrated that metabolic vinyl chloride (VC) degradation by an enrichment culture originating from groundwater was not affected by an equimolar concentration (50 μM) of cis-1,2-diChloroethene (cDCE). Only cDCE concentrations at a ratio of 2.4:1 (initial cDCE to VC concentration) caused minor inhibition of VC degradation. Furthermore, the degradation of VC was not affected by the presence of trans-1,2-diChloroethene (tDCE), 1,1-diChloroethene (1,1-DCE), triChloroethene (TCE), and tetraChloroethene (PCE) in equimolar concentrations (50 μM). Only cDCE and tDCE were cometabolically degraded in small amounts. The VC-degrading culture demonstrated a broad pH tolerance from 5 to 9 with an optimum between 6 and 7. Results also showed that the culture could degrade VC concentrations up to 1,800 μM (110 mg/L).
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Sequential anaerobic/aerobic biodegradation of Chloroethenes--aspects of field application.
Current opinion in biotechnology, 2011Co-Authors: Andreas Tiehm, Kathrin R. SchmidtAbstract:Because of a range of different industrial activities, sites contaminated with Chloroethenes are a world-wide problem. Chloroethenes can be biodegraded by reductive dechlorination under anaerobic conditions as well as by oxidation under aerobic conditions. The tendency of Chloroethenes to undergo reductive dechlorination decreases with a decreasing number of chlorine substituents, whereas with less chlorine substituents Chloroethenes more easily undergo oxidative degradation. There is currently a growing interest in aerobic metabolic degradation of Chloroethenes, which demonstrates advantages compared to cometabolic degradation pathways. Sequential anaerobic/aerobic biodegradation can overcome the disadvantages of reductive dechlorination and leads to complete mineralization of the chlorinated pollutants. This approach shows promise for site remediation in natural settings and in engineered systems.
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inhibition of aerobic metabolic cis 1 2 di Chloroethene biodegradation by other Chloroethenes
Water Research, 2010Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Andreas TiehmAbstract:Abstract The presence of other Chloroethenes influences aerobic metabolic biodegradation of cis-1,2-diChloroethene (cDCE). A new metabolically cDCE degrading enrichment culture was identified as also being capable of degrading vinyl chloride (VC), but not 1,1-diChloroethene (1,1DCE), trans-1,2-diChloroethene (tDCE), triChloroethene (TCE), or tetraChloroethene (PCE). The fastest degradation of cDCE was observed in the absence of any other Chloroethene. In the presence of a second Chloroethene (40–90 μM), the rate of cDCE (60 μM) degradation decreased in the following order: cDCE (+PCE) > cDCE (+tDCE) > cDCE (+VC)> cDCE (+1,1DCE) ≈ cDCE (+TCE). With increasing concentrations of VC, ranging from 10 to 110 μM, the rate of cDCE (60 μM) degradation decreased. This study demonstrates that the inhibiting effects of Chloroethene mixtures have to be considered during laboratory studies and bioremediation approaches based on metabolic cDCE degradation.
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Inhibition of aerobic metabolic cis-1,2-di-Chloroethene biodegradation by other Chloroethenes.
Water research, 2009Co-Authors: He-ping Zhao, Kathrin R. Schmidt, Andreas TiehmAbstract:The presence of other Chloroethenes influences aerobic metabolic biodegradation of cis-1,2-diChloroethene (cDCE). A new metabolically cDCE degrading enrichment culture was identified as also being capable of degrading vinyl chloride (VC), but not 1,1-diChloroethene (1,1DCE), trans-1,2-diChloroethene (tDCE), triChloroethene (TCE), or tetraChloroethene (PCE). The fastest degradation of cDCE was observed in the absence of any other Chloroethene. In the presence of a second Chloroethene (40-90 microM), the rate of cDCE (60 microM) degradation decreased in the following order: cDCE (+PCE) > cDCE (+tDCE) > cDCE (+VC)>cDCE (+1,1DCE) approximately cDCE (+TCE). With increasing concentrations of VC, ranging from 10 to 110 microM, the rate of cDCE (60 microM) degradation decreased. This study demonstrates that the inhibiting effects of Chloroethene mixtures have to be considered during laboratory studies and bioremediation approaches based on metabolic cDCE degradation.
Siyan Zhao - One of the best experts on this subject based on the ideXlab platform.
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Reductive dechlorination of high concentrations of Chloroethenes by a Dehalococcoides mccartyi strain 11G.
FEMS microbiology ecology, 2019Co-Authors: Siyan ZhaoAbstract:Chloroethenes are common groundwater and soil contaminants due to extensive historic utilization and inappropriate discharge. The tendency for Chloroethenes to become sequestered as dense non-aqueous phase liquids (DNAPL)-a point source to groundwater contamination and causing high concentrations of Chloroethenes in proximal aquifers poses a great challenge for remediation of Chloroethene contaminated sites. In this study, we report isolation and characterization of a Dehalococcoides mccartyi strain 11G which couples growth with reductive dechlorination of triChloroethenes (TCE), diChloroethene (DCE) isomers and vinyl chloride (VC) to ethene at a growth yield ranging from 2.47 ± 0.23 × 108 to 5.64 ± 0.43 × 108 cells/µmoles Cl- released and co-metabolically dechlorinates tetraChloroethene (PCE) in the presence of TCE. Compared with previous D. mccartyi strains showing dechlorination of TCE at up to 2.0 mM, strain 11G is distinguished by its capacity to dechlorinate Chloroethenes at initial concentrations of DCE isomers as high as 4 mM and TCE as high as 3.5 mM to ethene. Bioaugmentation of a contaminated microcosm with strain 11G resulted in complete detoxification of a mixture of 5 mM Chloroethenes (2.5 mM of each TCE and cis-DCE) after 40 days. Strain 11G is a promising candidate for in situ bioremediation of high-concentration-Chloroethene contaminated sites.
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detoxification of 1 1 2 trichloroethane to ethene by desulfitobacterium and identification of its functional reductase gene
PLOS ONE, 2015Co-Authors: Siyan Zhao, Chang DingAbstract:1,1,2-trichloroethane (1,1,2-TCA) has become a common groundwater pollutant due to historically extensive utilization, improper disposal, as well as from incomplete dechlorination of 1,1,2,2-tetrachloroethane. Currently, limited information is available on microbial detoxification of 1,1,2-TCA. Desulfitobacterium sp. strain PR, which was isolated from an anaerobic bioreactor maintained to dechlorinate Chloroethenes/ethanes, exhibited the capacity to dechlorinate 1,1,1-trichloroethane and chloroform. In this study, the dechlorinating ability of strain PR was further explored. Strain PR showed the capability to dechlorinate 1,1,2-TCA (~1.12 mM) predominantly to 1,2-dichloroethane (1,2-DCA) and chloroethane, and to trace amounts of vinyl chloride and ethene within 20 days. Strain PR coupled growth with dechlorination of 1,1,2-TCA to 1,2-DCA, while no cell growth was observed with dechlorination of 1,2-DCA to chloroethane. Later, through transcriptomic and enzymatic analysis, the reductive dehalogenase CtrA, which was previously reported to be responsible for 1,1,1-trichloroethane and chloroform dechlorination, was identified as the 1,1,2-TCA reductive dehalogenase. Since triChloroethene (TCE) is usually co-contaminated with 1,1,2-TCA, a co-culture containing Dehalococcoides mccartyi strain 11a capable of detoxifying TCE and 1,2-DCA and strain PR was established. Interestingly, this co-culture dechlorinated 1,1,2-TCA and TCE to the non-toxic end-product ethene within 48 days without chloroethane production. This novel pathway avoids production of the carcinogenic intermediate dechlorination product vinyl chloride, providing a more environmentally friendly strategy to treat 1,1,2-TCA.
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Dechlorination of 1,1,2-TCA and chloroform simultaneously by strain PR.
2015Co-Authors: Siyan Zhao, Chang DingAbstract:Note: CA, chloroethane; DCM, dichloromethane; MCM, chloromethane.
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Dechlorination of 1,1,2-TCA by a co-culture consisting of strain PR and a mixed culture GEO.
2015Co-Authors: Siyan Zhao, Chang DingAbstract:Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.
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Dechlorination of 1,1,2-TCA by Desulfitobacterium sp. strain PR.
2015Co-Authors: Siyan Zhao, Chang DingAbstract:Note: CA, chloroethane; VC, vinyl chloride; ETH, ethene.
Manuela Artal - One of the best experts on this subject based on the ideXlab platform.
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vapour liquid equilibria for the binary mixtures 1 propanol dibromomethane or bromochloromethane or 1 2 dichloroethane or 1 bromo 2 chloroethane at t 313 15 k
The Journal of Chemical Thermodynamics, 2005Co-Authors: Vanesa Gilhernandez, Pilar Garciagimenez, Manuela Artal, Santos Otin, Inmaculada VelascoAbstract:Abstract Isothermal (vapour + liquid) equilibria (VLE) at 313.15 K have been measured for liquid 1-propanol + dibromomethane, or + bromochloromethane or + 1,2-dichloroethane or + 1-bromo-2-chloroethane mixtures. The VLE data were reduced using the Redlich–Kister equation taking into consideration the vapour phase imperfection in terms of the 2nd molar virial coefficients. The excess molar Gibbs free energies of all the studied mixtures are positive and ranging from 794 J · mol−1 for (1-propanol + bromochloromethane) and 1052 J · mol−1 for (1-propanol + 1-bromo-2-chloroethane), at x = 0.5. The experimental results are compared with modified UNIFAC predictions.
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(Vapour + liquid) equilibria for the binary mixtures (1-propanol + dibromomethane, or + bromochloromethane, or + 1,2-dichloroethane or + 1-bromo-2-chloroethane) at T = 313.15 K
The Journal of Chemical Thermodynamics, 2005Co-Authors: V. Gil-hernández, Pilar García-giménez, Manuela Artal, Santos Otin, Inmaculada VelascoAbstract:Abstract Isothermal (vapour + liquid) equilibria (VLE) at 313.15 K have been measured for liquid 1-propanol + dibromomethane, or + bromochloromethane or + 1,2-dichloroethane or + 1-bromo-2-chloroethane mixtures. The VLE data were reduced using the Redlich–Kister equation taking into consideration the vapour phase imperfection in terms of the 2nd molar virial coefficients. The excess molar Gibbs free energies of all the studied mixtures are positive and ranging from 794 J · mol−1 for (1-propanol + bromochloromethane) and 1052 J · mol−1 for (1-propanol + 1-bromo-2-chloroethane), at x = 0.5. The experimental results are compared with modified UNIFAC predictions.