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Ivonne Nijenhuis - One of the best experts on this subject based on the ideXlab platform.
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Anaerobic biotransformation of hexachlorocyclohexane isomers by Dehalococcoides species and an enrichment culture
Biodegradation, 2018Co-Authors: Safdar Bashir, Carsten Vogt, Kevin Kuntze, Ivonne NijenhuisAbstract:The biotransformation of hexachlorocyclohexane isomers (HCH) by two Dehalococcoides mccartyi strains (195 and BTF08) and an enrichment culture was investigated and compared to conversion by the obligate anaerobic strain Clostridium pasteurianum strain DSMZ 525. The D. mccartyi strains preferentially transformed γ-HCH over α-HCH and δ-HCH isomers while β-HCH biotransformation was not significant. In case of the enrichment culture, γ-HCH was preferentially transformed over the δ-HCH, β-HCH and α-HCH isomers. Major observed metabolites in both cases were tetrachlorocyclohexene and as end products monochlorobenzene (MCB) and benzene. Dechlorination of the γ-HCH isomer was linked to an increase in cell numbers for strain 195. γ-HCH transformation was linked to considerable carbon stable isotope fractionation with the enrichment factor ε_c = − 5.5 ± 0.8‰ for D. mccartyi strain 195, ε_c = − 3.1 ± 0.4‰ for the enrichment culture and ε_c = − 4.1 ± 0.6‰ for co-metabolic transformation by C. pasteurianum .
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Iron oxides stimulate microbial monochlorobenzene in situ transformation in constructed wetlands and laboratory systems.
Science of The Total Environment, 2013Co-Authors: Marie Schmidt, Hans H. Richnow, Heidrun Paschke, Diana Wolfram, Jan Birkigt, Jörg Ahlheim, Ivonne NijenhuisAbstract:Abstract Natural wetlands are transition zones between anoxic ground and oxic surface water which may enhance the (bio)transformation potential for recalcitrant chloro-organic contaminants due to the unique geochemical conditions and gradients. Monochlorobenzene (MCB) is a frequently detected groundwater contaminant which is toxic and was thought to be persistent under anoxic conditions. Furthermore, to date, no degradation pathways for anoxic MCB removal have been proven in the field. Hence, it is important to investigate MCB biodegradation in the environment, as groundwater is an important drinking water source in many European countries. Therefore, two pilot-scale horizontal subsurface-flow constructed wetlands, planted and unplanted, were used to investigate the processes in situ contributing to the biotransformation of MCB in these gradient systems. The wetlands were fed with anoxic MCB-contaminated groundwater from a nearby aquifer in Bitterfeld, Germany. An overall MCB removal was observed in both wetlands, whereas just 10% of the original MCB inflow concentration was detected in the ponds. In particular in the gravel bed of the planted wetland, MCB removal was highest in summer season with 73 ± 9% compared to the unplanted one with 40 ± 5%. Whereas the MCB concentrations rapidly decreased in the transition zone of unplanted gravel to the pond, a significant MCB removal was already determined in the anoxic gravel bed of the planted system. The investigation of hydro-geochemical parameters revealed that iron and sulphate reduction were relevant redox processes in both wetlands. In parallel, the addition of ferric iron or nitrate stimulated the mineralisation of MCB in laboratory microcosms with anoxic groundwater from the same source, indicating that the potential for anaerobic microbial degradation of MCB is present at the field site.
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dehalogenation of diverse halogenated substrates by a highly enriched dehalococcoides containing culture derived from the contaminated mega site in bitterfeld
FEMS Microbiology Ecology, 2013Co-Authors: Theresa Kaufhold, Marie Schmidt, Danuta Cichocka, Marcell Nikolausz, Ivonne NijenhuisAbstract:An enrichment culture dominated by one type of Dehalococcoides sp. (83% of clones) was characterised. This culture, originally derived from contaminated groundwater from the area of Bitterfeld-Wolfen (Saxony-Anhalt, Germany), dehalogenates chlorinated ethenes to ethene. Further, the culture also dehalogenated vinyl bromide (VB) and 1,2-dichloroethane (DCA) to ethene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzene (TeCB), penta- and hexachlorobenzene (PeCB and HCB) to trichlorobenzenes (TCB), lindane to monochlorobenzene (MCB) and pentachlorophenol (PCP) to 2,3,4,6-tetrachlorophenol (TeCP). Growth was proven by quantitative PCR for all active cultures, except for those with TeCB, lindane and PCP. The growth yields obtained ranged from (2.9 ± 0.7) × 107 cells μmol−1 Br− released on VB to (34.8 ± 5.4) × 107 cells μmol−1 Cl− released on VC. Genes coding for nine putative reductive dehalogenases, the enzymes that mediate the respiratory process of dehalogenation, were identified. Phylogenetic analysis revealed eight reductive dehalogenases with similar sequences in other Dehalococcoides strains and one unique sequence.
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Detection of monochlorobenzene metabolizing bacteria under anoxic conditions by DNA-stable isotope probing
Biodegradation, 2011Co-Authors: Paula M. Martínez-lavanchy, Hans H. Richnow, Gwenaël Imfeld, Anja B. Dohrmann, Karin Trescher, Christoph C. Tebbe, Ivonne NijenhuisAbstract:Cultivation-independent analyses were applied to study the structural diversity of the bacterial community which developed in groundwater inoculated microcosms actively metabolizing monochlorobenzene (MCB) under anaerobic conditions. Addition of 13C-labelled MCB demonstrated that the community produced 13CO2 as a metabolite at slightly increasing rates over a period of 1,051 days while no 13C-methane evolved. Genetic profiles of partial 16S rRNA genes generated with the single-strand conformation polymorphism (SSCP) technique by PCR from directly extracted total DNA revealed that, despite the long incubation period, six replicate microcosms were characterized by almost the same microbial members. Nine distinguishable contributors to the SSCP-profiles were characterized by DNA sequencing, revealing the presence of different members from the phyla Proteobacteria, Fibrobacteres and from the candidate division OD1. DNA-stable isotope probing (SIP) was applied to distinguish the actual MCB metabolizing bacteria from the other community members. This study reveals for the first time the structural diversity of an anaerobic MCB metabolizing bacterial community. However, it also demonstrates the limitations of SIP to detect bacteria slowly metabolizing carbon sources under anaerobic conditions.
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Sensitive detection of anaerobic monochlorobenzene degradation using stable isotope tracers.
Environmental Science & Technology, 2007Co-Authors: Ivonne Nijenhuis, Matthias Kästner, Nicole Stelzer, Hans H. RichnowAbstract:Microbial degradation of monochlorobenzene (MCB) under anaerobic conditions was investigated using a stable isotope tracer under in and ex situ conditions. In situ microcosms were incubated directly in an anoxic aquifer and carbon derived from [13C6]-MCB was found to be incorporated into the microbial biomass. In laboratory microcosms, amended with [13C6]-MCB, anaerobic mineralization of MCB was indicated by the production of 13CO2. Further, recovery of the 13C-label in the fatty acids confirmed the assimilation of MCB-derived carbon into microbial biomass. The described approach may be applied to various other organic groundwater contaminants of concern using carbon (13C) as well as other stable isotope tracers, such as nitrogen (15N), allowing direct and sensitive detection of biodegradation.
Hans H. Richnow - One of the best experts on this subject based on the ideXlab platform.
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Diversity of dechlorination pathways and organohalide respiring bacteria in chlorobenzene dechlorinating enrichment cultures originating from river sludge
Biodegradation, 2014Co-Authors: Pieter Vandermeeren, Hans H. Richnow, Danuta Cichocka, Steffi Herrmann, Pieter Busschaert, Bart Lievens, Dirk SpringaelAbstract:Anaerobic reductive dechlorination of hexachlorobenzene (HCB) and three isomers of tetrachlorobenzene (TeCB) (1,2,3,4-, 1,2,3,5- and 1,2,4,5-TeCB) was investigated in microcosms containing chloroaromatic contaminated river sediment. All chlorobenzenes were dechlorinated to dichlorobenzene (DCB) or monochlorobenzene. From the sediment, a methanogenic sediment-free culture was obtained which dechlorinated HCB, pentachlorobenzene, three TeCB isomers, three trichlorobenzene (TCB) isomers (1,2,3-, 1,2,4- and 1,3,5-TCB) and 1,2-DCB. Dechlorination involved multiple pathways including the removal of doubly flanked, singly flanked and isolated chlorine substituents. 454-pyrosequencing of partial bacterial 16S rRNA genes amplified from selected chlorobenzene dechlorinating sediment-free enrichment cultures revealed the presence of a variety of bacterial species, including Dehalobacter and Dehalococcoides mccartyi , that were previously documented as organohalide respiring bacteria. A genus with apparent close relationship to Desulfitobacterium that also has been associated with organohalide respiration, composed the major fraction of the operational taxonomic units (OTUs). Another major OTU was linked with Sedimentibacter sp., a genus that was previously identified in strict co-cultures of consortia reductively dehalogenating chlorinated compounds. Our data point towards the existence of multiple interactions within highly chlorinated benzene dechlorinating communities.
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Iron oxides stimulate microbial monochlorobenzene in situ transformation in constructed wetlands and laboratory systems.
Science of The Total Environment, 2013Co-Authors: Marie Schmidt, Hans H. Richnow, Heidrun Paschke, Diana Wolfram, Jan Birkigt, Jörg Ahlheim, Ivonne NijenhuisAbstract:Abstract Natural wetlands are transition zones between anoxic ground and oxic surface water which may enhance the (bio)transformation potential for recalcitrant chloro-organic contaminants due to the unique geochemical conditions and gradients. Monochlorobenzene (MCB) is a frequently detected groundwater contaminant which is toxic and was thought to be persistent under anoxic conditions. Furthermore, to date, no degradation pathways for anoxic MCB removal have been proven in the field. Hence, it is important to investigate MCB biodegradation in the environment, as groundwater is an important drinking water source in many European countries. Therefore, two pilot-scale horizontal subsurface-flow constructed wetlands, planted and unplanted, were used to investigate the processes in situ contributing to the biotransformation of MCB in these gradient systems. The wetlands were fed with anoxic MCB-contaminated groundwater from a nearby aquifer in Bitterfeld, Germany. An overall MCB removal was observed in both wetlands, whereas just 10% of the original MCB inflow concentration was detected in the ponds. In particular in the gravel bed of the planted wetland, MCB removal was highest in summer season with 73 ± 9% compared to the unplanted one with 40 ± 5%. Whereas the MCB concentrations rapidly decreased in the transition zone of unplanted gravel to the pond, a significant MCB removal was already determined in the anoxic gravel bed of the planted system. The investigation of hydro-geochemical parameters revealed that iron and sulphate reduction were relevant redox processes in both wetlands. In parallel, the addition of ferric iron or nitrate stimulated the mineralisation of MCB in laboratory microcosms with anoxic groundwater from the same source, indicating that the potential for anaerobic microbial degradation of MCB is present at the field site.
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Detection of monochlorobenzene metabolizing bacteria under anoxic conditions by DNA-stable isotope probing
Biodegradation, 2011Co-Authors: Paula M. Martínez-lavanchy, Hans H. Richnow, Gwenaël Imfeld, Anja B. Dohrmann, Karin Trescher, Christoph C. Tebbe, Ivonne NijenhuisAbstract:Cultivation-independent analyses were applied to study the structural diversity of the bacterial community which developed in groundwater inoculated microcosms actively metabolizing monochlorobenzene (MCB) under anaerobic conditions. Addition of 13C-labelled MCB demonstrated that the community produced 13CO2 as a metabolite at slightly increasing rates over a period of 1,051 days while no 13C-methane evolved. Genetic profiles of partial 16S rRNA genes generated with the single-strand conformation polymorphism (SSCP) technique by PCR from directly extracted total DNA revealed that, despite the long incubation period, six replicate microcosms were characterized by almost the same microbial members. Nine distinguishable contributors to the SSCP-profiles were characterized by DNA sequencing, revealing the presence of different members from the phyla Proteobacteria, Fibrobacteres and from the candidate division OD1. DNA-stable isotope probing (SIP) was applied to distinguish the actual MCB metabolizing bacteria from the other community members. This study reveals for the first time the structural diversity of an anaerobic MCB metabolizing bacterial community. However, it also demonstrates the limitations of SIP to detect bacteria slowly metabolizing carbon sources under anaerobic conditions.
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Sensitive detection of anaerobic monochlorobenzene degradation using stable isotope tracers.
Environmental Science & Technology, 2007Co-Authors: Ivonne Nijenhuis, Matthias Kästner, Nicole Stelzer, Hans H. RichnowAbstract:Microbial degradation of monochlorobenzene (MCB) under anaerobic conditions was investigated using a stable isotope tracer under in and ex situ conditions. In situ microcosms were incubated directly in an anoxic aquifer and carbon derived from [13C6]-MCB was found to be incorporated into the microbial biomass. In laboratory microcosms, amended with [13C6]-MCB, anaerobic mineralization of MCB was indicated by the production of 13CO2. Further, recovery of the 13C-label in the fatty acids confirmed the assimilation of MCB-derived carbon into microbial biomass. The described approach may be applied to various other organic groundwater contaminants of concern using carbon (13C) as well as other stable isotope tracers, such as nitrogen (15N), allowing direct and sensitive detection of biodegradation.
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Isotopic fractionation indicates anaerobic monochlorobenzene biodegradation
Environmental Toxicology and Chemistry, 2005Co-Authors: Arno Kaschl, Sylvia Uhlig, Ivonne Nijenhuis, Holger Weiß, Matthias Kästner, Carsten Vogt, Hans H. RichnowAbstract:The concentration and isotopic composition of monochlorobenzene (MCB) was monitored in the plume of an anaerobic, contaminated aquifer in Bitterfeld, Germany. An enrichment in the carbon isotopic composition of more than 4 δ units was found at the fringes of the plume relative to the center (-26.5 ‰), suggesting the occurrence of in situ biodegradation of MCB. A similar enrichment was measured in a detailed cross-section of the plume and in depth-specific samples obtained in a multilevel sampling well. The latter samples gave a good correlation of MCB concentrations and respective isotopic composition according to the Rayleigh equation. On the other hand, batch experiments using the aerobic MCB-degrading strains Ralstonia sp. DSM 8910, Acidovorax facilis UFZ B517, Rhodococcus erythropolis UFZ B528, and Pseudomonas veronii UFZ B547 showed that the known aerobic pathway initiated by dioxygenases does not result in a significant isotopic fractionation. Thus, a novel anaerobic pathway resulting in an isotopic fractionation appears to be the predominant process of MCB degradation in this aquifer. The study also clearly demonstrates the usefulness of isotopic fractionation analysis to prove biodegradation directly in the field, even when microcosm studies are not available and a metabolic pathway has not yet been elucidated.
Xiaobin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Ozone promotion of monochlorobenzene catalytic oxidation over carbon nanotubes-supported copper oxide at high temperature
Catalysis Letters, 2013Co-Authors: Ru Chen, Dongdong Jin, Zhaoxia Ma, Fu Liu, Hangsheng Yang, Xiaobin ZhangAbstract:Ozone is found to promote the monochlorobenzene (CB) catalytic oxidation over carbon nanotubes supported copper oxide composite up to reaction temperature of 300 C. Especially at 250 C, a CB conversion of 99 %, together with a CO 2 selectivity of 98 %, was observed. The selective adsorption of CB, the promotion of Cu + to Cu 2+ oxidation, and the combination of O 3 and high temperature activated gas phase O 2 are all considered to attribute to the high CB conversion and CO 2 selectivity at temperature above 250 C. Graphical Abstract: Effects of O 3 on catalytic oxidation of CB over CuO X /CNTs were studied. A CB conversion of 99 % and a CO 2 selectivity of 98 % were achieved at 250 C, which could be mainly attributed to the synergy between the CB oxidation by O 3 and activated O 2 . [Figure not available: see fulltext.] © 2013 Springer Science+Business Media New York.
Carsten Vogt - One of the best experts on this subject based on the ideXlab platform.
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Anaerobic biotransformation of hexachlorocyclohexane isomers by Dehalococcoides species and an enrichment culture
Biodegradation, 2018Co-Authors: Safdar Bashir, Carsten Vogt, Kevin Kuntze, Ivonne NijenhuisAbstract:The biotransformation of hexachlorocyclohexane isomers (HCH) by two Dehalococcoides mccartyi strains (195 and BTF08) and an enrichment culture was investigated and compared to conversion by the obligate anaerobic strain Clostridium pasteurianum strain DSMZ 525. The D. mccartyi strains preferentially transformed γ-HCH over α-HCH and δ-HCH isomers while β-HCH biotransformation was not significant. In case of the enrichment culture, γ-HCH was preferentially transformed over the δ-HCH, β-HCH and α-HCH isomers. Major observed metabolites in both cases were tetrachlorocyclohexene and as end products monochlorobenzene (MCB) and benzene. Dechlorination of the γ-HCH isomer was linked to an increase in cell numbers for strain 195. γ-HCH transformation was linked to considerable carbon stable isotope fractionation with the enrichment factor ε_c = − 5.5 ± 0.8‰ for D. mccartyi strain 195, ε_c = − 3.1 ± 0.4‰ for the enrichment culture and ε_c = − 4.1 ± 0.6‰ for co-metabolic transformation by C. pasteurianum .
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Isotopic fractionation indicates anaerobic monochlorobenzene biodegradation
Environmental Toxicology and Chemistry, 2005Co-Authors: Arno Kaschl, Sylvia Uhlig, Ivonne Nijenhuis, Holger Weiß, Matthias Kästner, Carsten Vogt, Hans H. RichnowAbstract:The concentration and isotopic composition of monochlorobenzene (MCB) was monitored in the plume of an anaerobic, contaminated aquifer in Bitterfeld, Germany. An enrichment in the carbon isotopic composition of more than 4 δ units was found at the fringes of the plume relative to the center (-26.5 ‰), suggesting the occurrence of in situ biodegradation of MCB. A similar enrichment was measured in a detailed cross-section of the plume and in depth-specific samples obtained in a multilevel sampling well. The latter samples gave a good correlation of MCB concentrations and respective isotopic composition according to the Rayleigh equation. On the other hand, batch experiments using the aerobic MCB-degrading strains Ralstonia sp. DSM 8910, Acidovorax facilis UFZ B517, Rhodococcus erythropolis UFZ B528, and Pseudomonas veronii UFZ B547 showed that the known aerobic pathway initiated by dioxygenases does not result in a significant isotopic fractionation. Thus, a novel anaerobic pathway resulting in an isotopic fractionation appears to be the predominant process of MCB degradation in this aquifer. The study also clearly demonstrates the usefulness of isotopic fractionation analysis to prove biodegradation directly in the field, even when microcosm studies are not available and a metabolic pathway has not yet been elucidated.
Ru Chen - One of the best experts on this subject based on the ideXlab platform.
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Ozone promotion of monochlorobenzene catalytic oxidation over carbon nanotubes-supported copper oxide at high temperature
Catalysis Letters, 2013Co-Authors: Ru Chen, Dongdong Jin, Zhaoxia Ma, Fu Liu, Hangsheng Yang, Xiaobin ZhangAbstract:Ozone is found to promote the monochlorobenzene (CB) catalytic oxidation over carbon nanotubes supported copper oxide composite up to reaction temperature of 300 C. Especially at 250 C, a CB conversion of 99 %, together with a CO 2 selectivity of 98 %, was observed. The selective adsorption of CB, the promotion of Cu + to Cu 2+ oxidation, and the combination of O 3 and high temperature activated gas phase O 2 are all considered to attribute to the high CB conversion and CO 2 selectivity at temperature above 250 C. Graphical Abstract: Effects of O 3 on catalytic oxidation of CB over CuO X /CNTs were studied. A CB conversion of 99 % and a CO 2 selectivity of 98 % were achieved at 250 C, which could be mainly attributed to the synergy between the CB oxidation by O 3 and activated O 2 . [Figure not available: see fulltext.] © 2013 Springer Science+Business Media New York.