The Experts below are selected from a list of 6339 Experts worldwide ranked by ideXlab platform
Tillmann Lueders - One of the best experts on this subject based on the ideXlab platform.
-
electron acceptor dependent identification of key anaerobic toluene degraders at a Tar Oil contaminated aquifer by pyro sip
FEMS Microbiology Ecology, 2011Co-Authors: Giovanni Pilloni, Frederick Von Netzer, Marion Engel, Tillmann LuedersAbstract:Bioavailability of electron acceptors is probably the most limiting factor in the restoration of anoxic, contaminated environments. The oxidation of contaminants such as aromatic hydrocarbons, particularly in aquifers, often depends on the reduction of ferric iron or sulphate. We have previously detected a highly active fringe zone beneath a toluene plume at a Tar-Oil-contaminated aquifer in Germany, where a specialized community of contaminant degraders codominated by Desulfobulbaceae and Geobacteraceae had established. Although on-site geochemistry links degradation to sulphidogenic processes, dominating catabolic (benzylsuccinate synthase α-subunit, bssA) genes detected in situ appeared to be more related to those of Geobacter spp. Therefore, a stable isotope probing (SIP) incubation of sediment samples with (13)C(7)-toluene and comparative electron acceptor amendment was performed. We introduce pyrosequencing of templates from SIP microcosms as a powerful new strategy in SIP gradient interpretation (Pyro-SIP). Our results reveal the central role of Desulfobulbaceae in sulphidogenic toluene degradation in situ, and affiliate the detected bssA genes to this lineage. This and the absence of (13)C-labelled DNA of Geobacter spp. in SIP gradients preclude their relevance as toluene degraders in situ. In contrast, Betaproteobacteria related to Georgfuchsia spp. became labelled under iron-reducing conditions. Furthermore, secondary toluene degraders belonging to the Peptococcaceae detected in both treatments suggest the possibility of functional redundancy among anaerobic toluene degraders on site.
-
dna sip identifies sulfate reducing clostridia as important toluene degraders in Tar Oil contaminated aquifer sediment
The ISME Journal, 2010Co-Authors: Christian Winderl, Rainer U Meckenstock, Holger Penning, Frederick Von Netzer, Tillmann LuedersAbstract:Global groundwater resources are constantly challenged by a multitude of contaminants such as aromatic hydrocarbons. Especially in anaerobic habitats, a large diversity of unrecognized microbial populations may be responsible for their degradation. Still, our present understanding of the respective microbiota and their ecophysiology is almost exclusively based on a small number of cultured organisms, mostly within the Proteobacteria. Here, by DNA-based stable isotope probing (SIP), we directly identified the most active sulfate-reducing toluene degraders in a diverse sedimenTary microbial community originating from a Tar-Oil-contaminated aquifer at a former coal gasification plant. On incubation of fresh sediments with 13C7-toluene, the production of both sulfide and 13CO2 was clearly coupled to the 13C-labeling of DNA of microbes related to Desulfosporosinus spp. within the Peptococcaceae (Clostridia). The screening of labeled DNA fractions also suggested a novel benzylsuccinate synthase alpha-subunit (bssA) sequence type previously only detected in the environment to be tentatively affiliated with these degraders. However, carbon flow from the contaminant into degrader DNA was only ∼50%, pointing toward high ratios of heterotrophic CO2-fixation during assimilation of acetyl-CoA originating from the contaminant by these degraders. These findings demonstrate that the importance of non-proteobacterial populations in anaerobic aromatics degradation, as well as their specific ecophysiology in the subsurface may still be largely ungrasped.
-
high resolution analysis of contaminated aquifer sediments and groundwater what can be learned in terms of natural attenuation
Geomicrobiology Journal, 2010Co-Authors: Bettina Anneser, Christian Griebler, Tillmann Lueders, Giovanni Pilloni, Florian Einsiedl, Anne Bayer, Lars RichtersAbstract:High-resolution depth-resolved monitoring was applied to groundwater and sediments samples in a Tar Oil contaminated aquifer. Today, it is not fully clear, whether groundwater-based lines of evidence are always sufficient to adequately assess natural attenuation (NA) potentials and processes going on in situ. Our data unveiled small-scale heterogeneities, steep physical-chemical and microbial gradients, as well as hot spots of contaminants and biodegradation in the supposedly homogeneous sandy aquifer. The comparison of basic geochemical data revealed a fairly good agreement between sediment and groundwater samples. Nevertheless, a comprehensive understanding of both BTEX and PAH distribution, as well as redox processes involving insoluble electron acceptors, i.e., iron reduction, clearly asks for consideration of both, sediment and groundwater analysis. A thin BTEX plume right below the groundwater table was visible only in groundwater, while significant amounts of PAHs were present in sediments from dee...
-
depth resolved quantification of anaerobic toluene degraders and aquifer microbial community patterns in distinct redox zones of a Tar Oil contaminant plume
Applied and Environmental Microbiology, 2008Co-Authors: Christian Winderl, Rainer U Meckenstock, Christian Griebler, Bettina Anneser, Tillmann LuedersAbstract:The fate of organic contaminants in groundwater environments is controlled by a multitude of abiotic and biotic processes, such as transport, dilution, dispersion, and chemical or microbial degradation. The last is considered the only sustainable component of natural attenuation (9, 46). Due to large carbon loads and the low rates of oxygen replenishment to groundwater systems, oxygen is rapidly depleted upon contaminant impact (2). Therefore, within hydrocarbon-contaminated aquifers, anoxic contaminant plumes with distinct redox compartments are formed, where microbial guilds capable of using locally available electron donors and acceptors are active (9). Biodegradation processes occur at different rates in these redox zones (46), but it is still poorly understood which plume compartments are most relevant for net contaminant removal. Especially, overlapping countergradients of electron donors and acceptors are assumed to be hot spots of biodegradation (3, 12, 53, 54), a hypothesis that has recently been summarized as the “plume fringe concept” (4). Such redox gradients may be extant on very fine spatial scales; thus, a detailed characterization of redox species and intrinsic microbiota at appropriate spatial resolutions is a prerequisite for a better understanding of biodegradation processes. It is especially relevant to ask how the spatial distribution of plume compartments and degradation processes is correlated to local microbial communities in general and whether the distribution of specific contaminant degraders can inform us about the occurrence and localization of the respective processes. Local microbial community composition has been shown to yield important insights into the microbes characteristic of different contaminated zones, as well as into their putative involvement in specific transformation processes in aquifers (1, 13, 27, 39). However, the monitoring of microbial capacities and their distribution at contaminated sites as a basis for assessing natural attenuation and for promoting biota-based site management options is still in its infancy. This may be attributed partially to the fact that conventional multilevel groundwater sampling is performed usually with a depth resolution of meters (24, 49). This spatial resolution has been suggested to be inadequate for truly assessing ongoing natural attenuation processes (57). In this study, to address these questions, we have characterized microbial community distribution across a high-resolution depth profile of a Tar Oil-impacted aquifer at a former gasworks location, where hydrocarbon degradation has been reported to depend mainly on sulfate reduction (14, 59). We have specifically traced as a model system intrinsic populations of anaerobic toluene degraders by using their benzylsuccinate synthase (bssA) genes as specific catabolic markers (58). Benzylsuccinate synthase (Bss) is the key enzyme of anaerobic toluene oxidation and has repeatedly been proven to be a valuable functional marker gene for unknown anaerobic toluene degraders (6, 55, 58). Thus, we have shown for the Flingern site in Dusseldorf, Germany, that local anaerobic toluene degraders are dominated by an as-yet unaffiliated lineage of environmental bssA genes, tentatively termed “F1-cluster” bssA, which has ∼90% amino acid similarity to known geobacterial bssA genes (58). However, the identities of the degraders carrying these bssA genes, as well as their quantitative distribution and relevance for net toluene degradation in the contaminant plume, remain to be addressed. At the site, we have collected sediment cores and installed a unique high-resolution multilevel monitoring well (3). Using fine-scale hydrogeochemical measurements as well as spatially resolved qualitative and quantitative molecular microbial community analyses, we show that a highly specialized degrader community, as well as a surprisingly high abundance of specific anaerobic toluene degraders, resides within the biogeochemical gradient zone underneath the plume core. These findings show that the distribution of specific aquifer microbiota and redox and degradation processes in contaminated aquifers are tightly coupled.
Christian Griebler - One of the best experts on this subject based on the ideXlab platform.
-
high resolution analysis of contaminated aquifer sediments and groundwater what can be learned in terms of natural attenuation
Geomicrobiology Journal, 2010Co-Authors: Bettina Anneser, Christian Griebler, Tillmann Lueders, Giovanni Pilloni, Florian Einsiedl, Anne Bayer, Lars RichtersAbstract:High-resolution depth-resolved monitoring was applied to groundwater and sediments samples in a Tar Oil contaminated aquifer. Today, it is not fully clear, whether groundwater-based lines of evidence are always sufficient to adequately assess natural attenuation (NA) potentials and processes going on in situ. Our data unveiled small-scale heterogeneities, steep physical-chemical and microbial gradients, as well as hot spots of contaminants and biodegradation in the supposedly homogeneous sandy aquifer. The comparison of basic geochemical data revealed a fairly good agreement between sediment and groundwater samples. Nevertheless, a comprehensive understanding of both BTEX and PAH distribution, as well as redox processes involving insoluble electron acceptors, i.e., iron reduction, clearly asks for consideration of both, sediment and groundwater analysis. A thin BTEX plume right below the groundwater table was visible only in groundwater, while significant amounts of PAHs were present in sediments from dee...
-
thiobacillus thiophilus sp nov a chemolithoautotrophic thiosulfate oxidizing bacterium isolated from contaminated aquifer sediments
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Claudia Kellermann, Christian GrieblerAbstract:Strain D24TN(T) was enriched and isolated from sediment collected from a Tar Oil-contaminated aquifer at a former gasworks site located in Duesseldorf-Flingern, Germany. Cells of strain D24TN(T) were rod-shaped, non-spore-forming and stained Gram-negative. Thiosulfate was used as an electron donor. The organism was obligately chemolithoautotrophic and facultatively anaerobic, and grew with either oxygen or nitrate as electron acceptor. Growth was observed at pH values between 6.3 and 8.7 and at temperatures of -2 to 30 degrees C; optimum growth occurred at pH 7.5-8.3 and 25-30 degrees C. The DNA G+C content was 61.5 mol%. On the basis of the 16S rRNA gene sequence analysis, strain D24TN(T) clustered in the Betaproteobacteria and was most closely related to Thiobacillus denitrificans (97.6 %) and Thiobacillus thioparus (97.5 %). Based on the phenotypic, chemotaxonomic and phylogenetic data, strain D24TN(T) represents a novel species of the genus Thiobacillus, for which the name Thiobacillus thiophilus sp. nov. is proposed. The type strain is D24TN(T) (=DSM 19892(T)=JCM 15047(T)).
-
high resolution monitoring of biogeochemical gradients in a Tar Oil contaminated aquifer
Applied Geochemistry, 2008Co-Authors: Bettina Anneser, Rainer U Meckenstock, Florian Einsiedl, Lars Richters, Frank Wisotzky, Christian GrieblerAbstract:Abstract The detailed understanding of in situ biodegradation of petroleum hydrocarbons in porous aquifers requires knowledge on biogeochemical gradients, the distribution of individual redox species and microorganisms. The generally limited spatial resolution of conventional monitoring wells, however, hampers appropriate characterization of small-scale gradients and thus localization of the relevant processes. Groundwater sampling across a BTEX plume in a sandy aquifer by means of a novel high-resolution multi-level well (HR-MLW) is presented here. The presence of distinct and steep biogeochemical gradients is demonstrated in the centimeter and decimeter scale, which could not be resolved with a conventional multi-level well. The thin BTEX plume with a vertical extension of only 80 cm exhibited a decline of contaminant concentrations by two orders of magnitude within a few centimeters in the upper and lower fringe zone. The small-scale distribution of sulfate, sulfide and Fe(II) in relation to the contaminants and elevated δ 34 S and δ 18 O values of groundwater sulfate strongly indicated sulfate and iron reduction to be the dominant redox processes involved in biodegradation. High microbial activities and biomass especially at the plume fringes and the slope of chemical gradients supported the concept that the latter are regulated by microbial processes and transverse dispersion, i.e. vertical mixing of electron donors and acceptors. Transverse dispersion therefore was suggested to be a driving factor controlling biodegradation in porous aquifers, but not exclusively limiting natural attenuation processes at this site. Broad overlapping zones of electron donors and electron acceptors point towards additional factors limiting anaerobic biodegradation in situ . The identification of small-scale gradients substantially contributed to a better understanding of biodegradation processes and hence is a prerequisite for the development of reliable predictive mathematical models and future remediation strategies.
-
depth resolved quantification of anaerobic toluene degraders and aquifer microbial community patterns in distinct redox zones of a Tar Oil contaminant plume
Applied and Environmental Microbiology, 2008Co-Authors: Christian Winderl, Rainer U Meckenstock, Christian Griebler, Bettina Anneser, Tillmann LuedersAbstract:The fate of organic contaminants in groundwater environments is controlled by a multitude of abiotic and biotic processes, such as transport, dilution, dispersion, and chemical or microbial degradation. The last is considered the only sustainable component of natural attenuation (9, 46). Due to large carbon loads and the low rates of oxygen replenishment to groundwater systems, oxygen is rapidly depleted upon contaminant impact (2). Therefore, within hydrocarbon-contaminated aquifers, anoxic contaminant plumes with distinct redox compartments are formed, where microbial guilds capable of using locally available electron donors and acceptors are active (9). Biodegradation processes occur at different rates in these redox zones (46), but it is still poorly understood which plume compartments are most relevant for net contaminant removal. Especially, overlapping countergradients of electron donors and acceptors are assumed to be hot spots of biodegradation (3, 12, 53, 54), a hypothesis that has recently been summarized as the “plume fringe concept” (4). Such redox gradients may be extant on very fine spatial scales; thus, a detailed characterization of redox species and intrinsic microbiota at appropriate spatial resolutions is a prerequisite for a better understanding of biodegradation processes. It is especially relevant to ask how the spatial distribution of plume compartments and degradation processes is correlated to local microbial communities in general and whether the distribution of specific contaminant degraders can inform us about the occurrence and localization of the respective processes. Local microbial community composition has been shown to yield important insights into the microbes characteristic of different contaminated zones, as well as into their putative involvement in specific transformation processes in aquifers (1, 13, 27, 39). However, the monitoring of microbial capacities and their distribution at contaminated sites as a basis for assessing natural attenuation and for promoting biota-based site management options is still in its infancy. This may be attributed partially to the fact that conventional multilevel groundwater sampling is performed usually with a depth resolution of meters (24, 49). This spatial resolution has been suggested to be inadequate for truly assessing ongoing natural attenuation processes (57). In this study, to address these questions, we have characterized microbial community distribution across a high-resolution depth profile of a Tar Oil-impacted aquifer at a former gasworks location, where hydrocarbon degradation has been reported to depend mainly on sulfate reduction (14, 59). We have specifically traced as a model system intrinsic populations of anaerobic toluene degraders by using their benzylsuccinate synthase (bssA) genes as specific catabolic markers (58). Benzylsuccinate synthase (Bss) is the key enzyme of anaerobic toluene oxidation and has repeatedly been proven to be a valuable functional marker gene for unknown anaerobic toluene degraders (6, 55, 58). Thus, we have shown for the Flingern site in Dusseldorf, Germany, that local anaerobic toluene degraders are dominated by an as-yet unaffiliated lineage of environmental bssA genes, tentatively termed “F1-cluster” bssA, which has ∼90% amino acid similarity to known geobacterial bssA genes (58). However, the identities of the degraders carrying these bssA genes, as well as their quantitative distribution and relevance for net toluene degradation in the contaminant plume, remain to be addressed. At the site, we have collected sediment cores and installed a unique high-resolution multilevel monitoring well (3). Using fine-scale hydrogeochemical measurements as well as spatially resolved qualitative and quantitative molecular microbial community analyses, we show that a highly specialized degrader community, as well as a surprisingly high abundance of specific anaerobic toluene degraders, resides within the biogeochemical gradient zone underneath the plume core. These findings show that the distribution of specific aquifer microbiota and redox and degradation processes in contaminated aquifers are tightly coupled.
-
Combined Application of Stable Carbon Isotope Analysis and Specific Metabolites Determination for Assessing In Situ Degradation of Aromatic Hydrocarbons in a Tar Oil-Contaminated Aquifer
Environmental Science and Technology, 2004Co-Authors: Christian Griebler, Michael Safinowski, Hans Hermann Richnow, A Vieth, Rainer U MeckenstockAbstract:To evaluate the intrinsic bioremediation potential in an anoxic Tar Oil-contaminated aquifer at a former gasworks site, groundwater samples were qualitatively and quantitatively analyzed by compound-specific isotope analysis (CSIA) and signature metabolites analysis (SMA). 13C/12C fractionation data revealed conclusive evidence for in situ biodegradation of benzene, toluene, o-xylene, m/p-xylene, naphthalene, and 1-methylnaphthalene. In laboratory growth studies, 13C/12C isotope enrichment factors for anaerobic degradation of naphthalene (epsilon = -1.1 +/- 0.4) and 2-methylnaphthalene (epsilon = -0.9 +/- 0.1) were determined with the sulfate-reducing enrichment culture N47, which was isolated from the investigated test site. On the basis of these and other laboratory-derived enrichment factors from the literature, in situ biodegradation could be quantified for toluene, o-xylene, m/p-xylene, and naphthalene. Stable carbon isotope fractionation in the field was also observed for ethylbenzene, 2-methylnaphthalene, and benzothiophene but without providing conclusive results. Further evidence for the in situ turnover of individual BTEX compounds was provided by the presence of acetophenone, o-toluic acid, and p-toluic acid, three intermediates in the anaerobic degradation of ethylbenzene, o-xylene, and p-xylene, respectively. A number of groundwater samples also contained naphthyl-2-methylsuccinic acid, a metabolite that is highly specific for the anaerobic degradation of 2-methylnaphthalene. Additional metabolites that provided evidence on the anaerobic in situ degradation of naphthalenes were 1-naphthoic acid, 2-naphthoic acid, 1,2,3,4-tetrahydronaphthoic acid, and 5,6,7,8-tetrahydronaphthoic acid. 2-Carboxybenzothiophene, 5-carboxybenzothiophene, a putative further carboxybenzothiophene isomer, and the reduced derivative dihydrocarboxybenzothiophene indicated the anaerobic conversion of the heterocyclic aromatic hydrocarbon benzothiophene. The combined application of CSIA and SMA, as two reliable and independent tools to collect direct evidence on intrinsic bioremediation, leads to a substantially improved evaluation of natural attenuation in situ.
Rainer U Meckenstock - One of the best experts on this subject based on the ideXlab platform.
-
dna sip identifies sulfate reducing clostridia as important toluene degraders in Tar Oil contaminated aquifer sediment
The ISME Journal, 2010Co-Authors: Christian Winderl, Rainer U Meckenstock, Holger Penning, Frederick Von Netzer, Tillmann LuedersAbstract:Global groundwater resources are constantly challenged by a multitude of contaminants such as aromatic hydrocarbons. Especially in anaerobic habitats, a large diversity of unrecognized microbial populations may be responsible for their degradation. Still, our present understanding of the respective microbiota and their ecophysiology is almost exclusively based on a small number of cultured organisms, mostly within the Proteobacteria. Here, by DNA-based stable isotope probing (SIP), we directly identified the most active sulfate-reducing toluene degraders in a diverse sedimenTary microbial community originating from a Tar-Oil-contaminated aquifer at a former coal gasification plant. On incubation of fresh sediments with 13C7-toluene, the production of both sulfide and 13CO2 was clearly coupled to the 13C-labeling of DNA of microbes related to Desulfosporosinus spp. within the Peptococcaceae (Clostridia). The screening of labeled DNA fractions also suggested a novel benzylsuccinate synthase alpha-subunit (bssA) sequence type previously only detected in the environment to be tentatively affiliated with these degraders. However, carbon flow from the contaminant into degrader DNA was only ∼50%, pointing toward high ratios of heterotrophic CO2-fixation during assimilation of acetyl-CoA originating from the contaminant by these degraders. These findings demonstrate that the importance of non-proteobacterial populations in anaerobic aromatics degradation, as well as their specific ecophysiology in the subsurface may still be largely ungrasped.
-
high resolution monitoring of biogeochemical gradients in a Tar Oil contaminated aquifer
Applied Geochemistry, 2008Co-Authors: Bettina Anneser, Rainer U Meckenstock, Florian Einsiedl, Lars Richters, Frank Wisotzky, Christian GrieblerAbstract:Abstract The detailed understanding of in situ biodegradation of petroleum hydrocarbons in porous aquifers requires knowledge on biogeochemical gradients, the distribution of individual redox species and microorganisms. The generally limited spatial resolution of conventional monitoring wells, however, hampers appropriate characterization of small-scale gradients and thus localization of the relevant processes. Groundwater sampling across a BTEX plume in a sandy aquifer by means of a novel high-resolution multi-level well (HR-MLW) is presented here. The presence of distinct and steep biogeochemical gradients is demonstrated in the centimeter and decimeter scale, which could not be resolved with a conventional multi-level well. The thin BTEX plume with a vertical extension of only 80 cm exhibited a decline of contaminant concentrations by two orders of magnitude within a few centimeters in the upper and lower fringe zone. The small-scale distribution of sulfate, sulfide and Fe(II) in relation to the contaminants and elevated δ 34 S and δ 18 O values of groundwater sulfate strongly indicated sulfate and iron reduction to be the dominant redox processes involved in biodegradation. High microbial activities and biomass especially at the plume fringes and the slope of chemical gradients supported the concept that the latter are regulated by microbial processes and transverse dispersion, i.e. vertical mixing of electron donors and acceptors. Transverse dispersion therefore was suggested to be a driving factor controlling biodegradation in porous aquifers, but not exclusively limiting natural attenuation processes at this site. Broad overlapping zones of electron donors and electron acceptors point towards additional factors limiting anaerobic biodegradation in situ . The identification of small-scale gradients substantially contributed to a better understanding of biodegradation processes and hence is a prerequisite for the development of reliable predictive mathematical models and future remediation strategies.
-
depth resolved quantification of anaerobic toluene degraders and aquifer microbial community patterns in distinct redox zones of a Tar Oil contaminant plume
Applied and Environmental Microbiology, 2008Co-Authors: Christian Winderl, Rainer U Meckenstock, Christian Griebler, Bettina Anneser, Tillmann LuedersAbstract:The fate of organic contaminants in groundwater environments is controlled by a multitude of abiotic and biotic processes, such as transport, dilution, dispersion, and chemical or microbial degradation. The last is considered the only sustainable component of natural attenuation (9, 46). Due to large carbon loads and the low rates of oxygen replenishment to groundwater systems, oxygen is rapidly depleted upon contaminant impact (2). Therefore, within hydrocarbon-contaminated aquifers, anoxic contaminant plumes with distinct redox compartments are formed, where microbial guilds capable of using locally available electron donors and acceptors are active (9). Biodegradation processes occur at different rates in these redox zones (46), but it is still poorly understood which plume compartments are most relevant for net contaminant removal. Especially, overlapping countergradients of electron donors and acceptors are assumed to be hot spots of biodegradation (3, 12, 53, 54), a hypothesis that has recently been summarized as the “plume fringe concept” (4). Such redox gradients may be extant on very fine spatial scales; thus, a detailed characterization of redox species and intrinsic microbiota at appropriate spatial resolutions is a prerequisite for a better understanding of biodegradation processes. It is especially relevant to ask how the spatial distribution of plume compartments and degradation processes is correlated to local microbial communities in general and whether the distribution of specific contaminant degraders can inform us about the occurrence and localization of the respective processes. Local microbial community composition has been shown to yield important insights into the microbes characteristic of different contaminated zones, as well as into their putative involvement in specific transformation processes in aquifers (1, 13, 27, 39). However, the monitoring of microbial capacities and their distribution at contaminated sites as a basis for assessing natural attenuation and for promoting biota-based site management options is still in its infancy. This may be attributed partially to the fact that conventional multilevel groundwater sampling is performed usually with a depth resolution of meters (24, 49). This spatial resolution has been suggested to be inadequate for truly assessing ongoing natural attenuation processes (57). In this study, to address these questions, we have characterized microbial community distribution across a high-resolution depth profile of a Tar Oil-impacted aquifer at a former gasworks location, where hydrocarbon degradation has been reported to depend mainly on sulfate reduction (14, 59). We have specifically traced as a model system intrinsic populations of anaerobic toluene degraders by using their benzylsuccinate synthase (bssA) genes as specific catabolic markers (58). Benzylsuccinate synthase (Bss) is the key enzyme of anaerobic toluene oxidation and has repeatedly been proven to be a valuable functional marker gene for unknown anaerobic toluene degraders (6, 55, 58). Thus, we have shown for the Flingern site in Dusseldorf, Germany, that local anaerobic toluene degraders are dominated by an as-yet unaffiliated lineage of environmental bssA genes, tentatively termed “F1-cluster” bssA, which has ∼90% amino acid similarity to known geobacterial bssA genes (58). However, the identities of the degraders carrying these bssA genes, as well as their quantitative distribution and relevance for net toluene degradation in the contaminant plume, remain to be addressed. At the site, we have collected sediment cores and installed a unique high-resolution multilevel monitoring well (3). Using fine-scale hydrogeochemical measurements as well as spatially resolved qualitative and quantitative molecular microbial community analyses, we show that a highly specialized degrader community, as well as a surprisingly high abundance of specific anaerobic toluene degraders, resides within the biogeochemical gradient zone underneath the plume core. These findings show that the distribution of specific aquifer microbiota and redox and degradation processes in contaminated aquifers are tightly coupled.
-
Combined Application of Stable Carbon Isotope Analysis and Specific Metabolites Determination for Assessing In Situ Degradation of Aromatic Hydrocarbons in a Tar Oil-Contaminated Aquifer
Environmental Science and Technology, 2004Co-Authors: Christian Griebler, Michael Safinowski, Hans Hermann Richnow, A Vieth, Rainer U MeckenstockAbstract:To evaluate the intrinsic bioremediation potential in an anoxic Tar Oil-contaminated aquifer at a former gasworks site, groundwater samples were qualitatively and quantitatively analyzed by compound-specific isotope analysis (CSIA) and signature metabolites analysis (SMA). 13C/12C fractionation data revealed conclusive evidence for in situ biodegradation of benzene, toluene, o-xylene, m/p-xylene, naphthalene, and 1-methylnaphthalene. In laboratory growth studies, 13C/12C isotope enrichment factors for anaerobic degradation of naphthalene (epsilon = -1.1 +/- 0.4) and 2-methylnaphthalene (epsilon = -0.9 +/- 0.1) were determined with the sulfate-reducing enrichment culture N47, which was isolated from the investigated test site. On the basis of these and other laboratory-derived enrichment factors from the literature, in situ biodegradation could be quantified for toluene, o-xylene, m/p-xylene, and naphthalene. Stable carbon isotope fractionation in the field was also observed for ethylbenzene, 2-methylnaphthalene, and benzothiophene but without providing conclusive results. Further evidence for the in situ turnover of individual BTEX compounds was provided by the presence of acetophenone, o-toluic acid, and p-toluic acid, three intermediates in the anaerobic degradation of ethylbenzene, o-xylene, and p-xylene, respectively. A number of groundwater samples also contained naphthyl-2-methylsuccinic acid, a metabolite that is highly specific for the anaerobic degradation of 2-methylnaphthalene. Additional metabolites that provided evidence on the anaerobic in situ degradation of naphthalenes were 1-naphthoic acid, 2-naphthoic acid, 1,2,3,4-tetrahydronaphthoic acid, and 5,6,7,8-tetrahydronaphthoic acid. 2-Carboxybenzothiophene, 5-carboxybenzothiophene, a putative further carboxybenzothiophene isomer, and the reduced derivative dihydrocarboxybenzothiophene indicated the anaerobic conversion of the heterocyclic aromatic hydrocarbon benzothiophene. The combined application of CSIA and SMA, as two reliable and independent tools to collect direct evidence on intrinsic bioremediation, leads to a substantially improved evaluation of natural attenuation in situ.
Juliane Hollender - One of the best experts on this subject based on the ideXlab platform.
-
Quinoline and derivatives at a Tar Oil contaminated site: hydroxylated products as indicator for natural attenuation?
Environmental Science & Technology, 2007Co-Authors: Anne-kirsten Reineke, Thomas Göen, And Alfred Preiss, Juliane HollenderAbstract:LC-MS-MS analysis of groundwater of a Tar Oil contaminated site (a former coal mine and coking plant in Castrop-Rauxel, Germany) showed the occurrence of the N-heterocycles quinoline and isoquinoline as well as their hydroxylated and hydrogenated metabolites. The concentrations of the hydroxylated compounds, 2(1H)-quinolinone and 1(2H)-isoquinolinone, were significantly higher than those of the nonsubstituted parent compounds. Therefore, exclusive quantification of the parent compounds leads to an underestimation of the amount of N-heterocycles present in the groundwater. Microbial degradation experiments of quinoline and isoquinoline with aquifer material of the site as inocculum showed the formation of hydroxylated and hydrogenated products under sulfate-reducing conditions, the prevailing conditions in the field. However, since analyses of seven Tar products showed that these compounds are also primary constituents, their detection in groundwater is found to be a nonsufficient indicator for the occurrence of biological natural attenuation processes. Instead, the ratio of hydroxylated to parent compound (R{sub metabolite}) is proposed as a useful indicator. We found that 65-83% of all groundwater samples showed R{sub metabolite} for 2(1H)-quinolinone, 1(2H)-isoquinolinone, 3,4-dihydro-2(1H)-quinolinone, and 3,4-dihydro-1(2H)-isoquinolinone, which was higher than the highest ratio found in Tar products. With respect to the observed partition coefficient between Tar Oil and water of 3.5more » for quinoline and isoquinoline and 0.3 for 2(1H)-quinolinone and 1(2H)-isoquinolinone, the ratio in groundwater would be approximately 10 times higher than the ratio in Tar Oil. When paying attention to these two parameters, 19-31% of groundwater samples exceed the highest Tar Oil ratio. This indicates that biological processes take place in the aquifer of the site and R{sub metabolite} is an applicable indicator for natural attenuation. 42 refs., 6 figs., 2 tabs.« less
-
simultaneous determination of nso heterocycles homocycles and their metabolites in groundwater of Tar Oil contaminated sites using lc with diode array uv and fluorescence detection
Journal of Chromatography A, 2005Co-Authors: Matthias Mundt, Juliane HollenderAbstract:Abstract For monitoring groundwater at Tar Oil contaminated sites a simple method of analysis was developed for the simultaneous detection of several NSO heterocyclic compounds, homocyclic compounds, mobile two- and three-cyclic PAHs and selected metabolites. The groundwater samples are enriched using SPE with polymer material at pH 4. Chromatographic separation and detection is performed by LC with diode array UV or fluorescence detection. The recoveries of 25 selected compounds were mostly between 80–110% and the detection limits were 0.4–2.4 μg/L for UV detection and for the fluorescence detectable compounds 0.4–140 ng/L. The method was successfully applied to groundwater samples from a wood preserving facility. Especially benzo( b )thiophene showed an increasing dominance downgradient of the source. Detection of metabolites, such as 1-hydroxyiso-, 2-hydroxyquinoline and 2-hydroxy-4-methylquinoline, 2-naphthoic acid, and 1-indanone, indicating in situ biodegradation, was confirmed by LC-ESI–MS analysis.
Christian Winderl - One of the best experts on this subject based on the ideXlab platform.
-
dna sip identifies sulfate reducing clostridia as important toluene degraders in Tar Oil contaminated aquifer sediment
The ISME Journal, 2010Co-Authors: Christian Winderl, Rainer U Meckenstock, Holger Penning, Frederick Von Netzer, Tillmann LuedersAbstract:Global groundwater resources are constantly challenged by a multitude of contaminants such as aromatic hydrocarbons. Especially in anaerobic habitats, a large diversity of unrecognized microbial populations may be responsible for their degradation. Still, our present understanding of the respective microbiota and their ecophysiology is almost exclusively based on a small number of cultured organisms, mostly within the Proteobacteria. Here, by DNA-based stable isotope probing (SIP), we directly identified the most active sulfate-reducing toluene degraders in a diverse sedimenTary microbial community originating from a Tar-Oil-contaminated aquifer at a former coal gasification plant. On incubation of fresh sediments with 13C7-toluene, the production of both sulfide and 13CO2 was clearly coupled to the 13C-labeling of DNA of microbes related to Desulfosporosinus spp. within the Peptococcaceae (Clostridia). The screening of labeled DNA fractions also suggested a novel benzylsuccinate synthase alpha-subunit (bssA) sequence type previously only detected in the environment to be tentatively affiliated with these degraders. However, carbon flow from the contaminant into degrader DNA was only ∼50%, pointing toward high ratios of heterotrophic CO2-fixation during assimilation of acetyl-CoA originating from the contaminant by these degraders. These findings demonstrate that the importance of non-proteobacterial populations in anaerobic aromatics degradation, as well as their specific ecophysiology in the subsurface may still be largely ungrasped.
-
depth resolved quantification of anaerobic toluene degraders and aquifer microbial community patterns in distinct redox zones of a Tar Oil contaminant plume
Applied and Environmental Microbiology, 2008Co-Authors: Christian Winderl, Rainer U Meckenstock, Christian Griebler, Bettina Anneser, Tillmann LuedersAbstract:The fate of organic contaminants in groundwater environments is controlled by a multitude of abiotic and biotic processes, such as transport, dilution, dispersion, and chemical or microbial degradation. The last is considered the only sustainable component of natural attenuation (9, 46). Due to large carbon loads and the low rates of oxygen replenishment to groundwater systems, oxygen is rapidly depleted upon contaminant impact (2). Therefore, within hydrocarbon-contaminated aquifers, anoxic contaminant plumes with distinct redox compartments are formed, where microbial guilds capable of using locally available electron donors and acceptors are active (9). Biodegradation processes occur at different rates in these redox zones (46), but it is still poorly understood which plume compartments are most relevant for net contaminant removal. Especially, overlapping countergradients of electron donors and acceptors are assumed to be hot spots of biodegradation (3, 12, 53, 54), a hypothesis that has recently been summarized as the “plume fringe concept” (4). Such redox gradients may be extant on very fine spatial scales; thus, a detailed characterization of redox species and intrinsic microbiota at appropriate spatial resolutions is a prerequisite for a better understanding of biodegradation processes. It is especially relevant to ask how the spatial distribution of plume compartments and degradation processes is correlated to local microbial communities in general and whether the distribution of specific contaminant degraders can inform us about the occurrence and localization of the respective processes. Local microbial community composition has been shown to yield important insights into the microbes characteristic of different contaminated zones, as well as into their putative involvement in specific transformation processes in aquifers (1, 13, 27, 39). However, the monitoring of microbial capacities and their distribution at contaminated sites as a basis for assessing natural attenuation and for promoting biota-based site management options is still in its infancy. This may be attributed partially to the fact that conventional multilevel groundwater sampling is performed usually with a depth resolution of meters (24, 49). This spatial resolution has been suggested to be inadequate for truly assessing ongoing natural attenuation processes (57). In this study, to address these questions, we have characterized microbial community distribution across a high-resolution depth profile of a Tar Oil-impacted aquifer at a former gasworks location, where hydrocarbon degradation has been reported to depend mainly on sulfate reduction (14, 59). We have specifically traced as a model system intrinsic populations of anaerobic toluene degraders by using their benzylsuccinate synthase (bssA) genes as specific catabolic markers (58). Benzylsuccinate synthase (Bss) is the key enzyme of anaerobic toluene oxidation and has repeatedly been proven to be a valuable functional marker gene for unknown anaerobic toluene degraders (6, 55, 58). Thus, we have shown for the Flingern site in Dusseldorf, Germany, that local anaerobic toluene degraders are dominated by an as-yet unaffiliated lineage of environmental bssA genes, tentatively termed “F1-cluster” bssA, which has ∼90% amino acid similarity to known geobacterial bssA genes (58). However, the identities of the degraders carrying these bssA genes, as well as their quantitative distribution and relevance for net toluene degradation in the contaminant plume, remain to be addressed. At the site, we have collected sediment cores and installed a unique high-resolution multilevel monitoring well (3). Using fine-scale hydrogeochemical measurements as well as spatially resolved qualitative and quantitative molecular microbial community analyses, we show that a highly specialized degrader community, as well as a surprisingly high abundance of specific anaerobic toluene degraders, resides within the biogeochemical gradient zone underneath the plume core. These findings show that the distribution of specific aquifer microbiota and redox and degradation processes in contaminated aquifers are tightly coupled.