The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mary A Voytek - One of the best experts on this subject based on the ideXlab platform.
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Stimulation of methane generation from nonproductive coal by addition of nutrients or a microbial consortium.
Applied and environmental microbiology, 2010Co-Authors: Elizabeth J Jones, Mary A Voytek, Margo D. Corum, William H. OremAbstract:Biogenic formation of methane from coal is of great interest as an underexploited source of clean energy. The goal of some coal bed producers is to extend coal bed methane productivity and to utilize hydrocarbon wastes such as coal slurry to generate new methane. However, the process and factors controlling the process, and thus ways to stimulate it, are poorly understood. Subbituminous coal from a nonproductive well in south Texas was stimulated to produce methane in Microcosms when the native population was supplemented with nutrients (biostimulation) or when nutrients and a consortium of bacteria and methanogens enriched from wetland sediment were added (bioaugmentation). The native population enriched by nutrient addition included Pseudomonas spp., Veillonellaceae, and Methanosarcina barkeri. The bioaugmented Microcosm generated methane more rapidly and to a higher concentration than the biostimulated Microcosm. Dissolved organics, including long-chain fatty acids, single-ring aromatics, and long-chain alkanes accumulated in the first 39 days of the bioaugmented Microcosm and were then degraded, accompanied by generation of methane. The bioaugmented Microcosm was dominated by Geobacter sp., and most of the methane generation was associated with growth of Methanosaeta concilii. The ability of the bioaugmentation culture to produce methane from coal intermediates was confirmed in incubations of culture with representative organic compounds. This study indicates that methane production could be stimulated at the nonproductive field site and that low microbial biomass may be limiting in situ methane generation. In addition, the Microcosm study suggests that the pathway for generating methane from coal involves complex microbial partnerships.
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degradation of 1 1 2 2 tetrachloroethane and accumulation of vinyl chloride in wetland sediment Microcosms and in situ porewater biogeochemical controls and associations with microbial communities
Journal of Contaminant Hydrology, 2004Co-Authors: Michelle M Lorah, Mary A VoytekAbstract:The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory Microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The Microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in Microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as Microcosms constructed with sediment that was methanogenic only throughout the incubation. The Microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in Microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in Microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.
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effect of fe iii on 1 1 2 2 tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the aberdeen proving ground
Bioremediation Journal, 2004Co-Authors: Elizabeth J Jones, Mary A Voytek, Michelle M LorahAbstract:1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek (MD), where dechlorination occurs. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways lead to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The goal of this investigation was to determine whether microbially-available Fe(III) in the wetland surface sediment influenced the fate of TeCA and its daughter products. Differences were identified in the TeCA degradation pathway between Microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) Microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated Microcosms than untreated Microcosms. The Microcosm incubations and subsequent experiments with the Microcosm materials showed that AFO treatment resulted...
Daryl F Dwyer - One of the best experts on this subject based on the ideXlab platform.
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degradation of trichloroethylene in wetland Microcosms containing broad leaved cattail and eastern cottonwood
Water Research, 2002Co-Authors: Jamie L Bankston, Daniel L Sola, Andrew T Komor, Daryl F DwyerAbstract:Remediation of aquifers containing trichloroethylene (TCE) relies primarily on physical extraction of contaminated groundwater and soil. Unfortunately, this is typically expensive and does not always attain the desired treatment goals. In situ bioremediation via natural attenuation is an alternative treatment process in which TCE is transformed by indigenous microorganisms and plants. In this study, TCE was observed in a surficial aquifer that discharges into a wetland. Experiments were undertaken to determine whether natural attenuation of TCE in the wetland was possible. Microcosms were constructed using sandy soil7eastern cottonwoods (Populus deltoides) from the wetland’s edge and organic soil7broad-leaved cattails (Typha latifolia) from the wetland’s interior. [ 14 C] TCE was added to each Microcosm (1.27mCi). Overtime, 14 C was recovered from four Microcosm compartments: (1) as 14 C bound to soil and water, (2) as volatilized [ 14 C] TCE, (3) as [ 14 C] CO2 produced by mineralization of [ 14 C] TCE, and (4) as 14 C incorporated into the plants. Total recoveries of the 14 C-label ranged from 73.6% to 95.8%. Volatilized [ 14 C] TCE accounted for the majority (>50%) of the recovered label. In Microcosms without plants, [ 14 C] CO2 represented 3.2% (organic soil) to 15.6% (sandy soil) of the recovered 14 C, indicating that TCE was mineralized by indigenous microorganisms. The presence of the broad-leaved cattail resulted in increased production of [ 14 C] CO2 to 5.3% in the organic soil. The data thus suggest that natural attenuation is a potential bioremediative strategy for TCEcontaminated wetlands. r 2002 Published by Elsevier Science Ltd.
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degradation of trichloroethylene in wetland Microcosms containing broad leaved cattail and eastern cottonwood
Water Research, 2002Co-Authors: Jamie L Bankston, Daniel L Sola, Andrew T Komor, Daryl F DwyerAbstract:Remediation of aquifers containing trichloroethylene (TCE) relies primarily on physical extraction of contaminated groundwater and soil. Unfortunately, this is typically expensive and does not always attain the desired treatment goals. In situ bioremediation via natural attenuation is an alternative treatment process in which TCE is transformed by indigenous microorganisms and plants. In this study, TCE was observed in a surficial aquifer that discharges into a wetland. Experiments were undertaken to determine whether natural attenuation of TCE in the wetland was possible. Microcosms were constructed using sandy soil7eastern cottonwoods (Populus deltoides) from the wetland’s edge and organic soil7broad-leaved cattails (Typha latifolia) from the wetland’s interior. [ 14 C] TCE was added to each Microcosm (1.27mCi). Overtime, 14 C was recovered from four Microcosm compartments: (1) as 14 C bound to soil and water, (2) as volatilized [ 14 C] TCE, (3) as [ 14 C] CO2 produced by mineralization of [ 14 C] TCE, and (4) as 14 C incorporated into the plants. Total recoveries of the 14 C-label ranged from 73.6% to 95.8%. Volatilized [ 14 C] TCE accounted for the majority (>50%) of the recovered label. In Microcosms without plants, [ 14 C] CO2 represented 3.2% (organic soil) to 15.6% (sandy soil) of the recovered 14 C, indicating that TCE was mineralized by indigenous microorganisms. The presence of the broad-leaved cattail resulted in increased production of [ 14 C] CO2 to 5.3% in the organic soil. The data thus suggest that natural attenuation is a potential bioremediative strategy for TCEcontaminated wetlands. r 2002 Published by Elsevier Science Ltd.
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behavior of pollutant degrading microorganisms in aquifers predictions for genetically engineered organisms
Environmental Science & Technology, 1994Co-Authors: Mary Lou Krumme, Kenneth N. Timmis, Richard L Smith, Joerg Egestorff, Suzanne M Thiem, James M Tiedje, Daryl F DwyerAbstract:Bioremediation via environmental introductions of degradative microorganisms requires that the microbes survive in substantial numbers and effect an increase in the rate and extent of pollutant removal. Combined field and Microcosm studies were used to assess these abilities for laboratory-grown bacteria. Following introduction into a contaminated aquifer, viable cells of Pseudomonas sp. B13 were present in the contaminant plume for 447 days; die-off was rapid in pristine areas. In aquifer Microcosms, survival of B13 and FR120, a genetically engineered derivative of B13 having enhanced catabolic capabilities for substituted aromatics, was comparable to B13 field results; both bacteria degraded target pollutants in Microcosms made with aquifer samples from the aerobic zone of the pollutant plume. Results suggest that field studies with nonrecombinant microorganisms may be coupled to laboratory studies with derivative strains to estimate their bioremediative efficacy. Furthermore, laboratory strains of bacteria can survive for extended periods of time in nature and thus may have important bioremediative applications. 33 refs., 4 figs., 1 tab.
Michelle M Lorah - One of the best experts on this subject based on the ideXlab platform.
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degradation of 1 1 2 2 tetrachloroethane and accumulation of vinyl chloride in wetland sediment Microcosms and in situ porewater biogeochemical controls and associations with microbial communities
Journal of Contaminant Hydrology, 2004Co-Authors: Michelle M Lorah, Mary A VoytekAbstract:The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory Microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The Microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in Microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as Microcosms constructed with sediment that was methanogenic only throughout the incubation. The Microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in Microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in Microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.
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effect of fe iii on 1 1 2 2 tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the aberdeen proving ground
Bioremediation Journal, 2004Co-Authors: Elizabeth J Jones, Mary A Voytek, Michelle M LorahAbstract:1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek (MD), where dechlorination occurs. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways lead to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The goal of this investigation was to determine whether microbially-available Fe(III) in the wetland surface sediment influenced the fate of TeCA and its daughter products. Differences were identified in the TeCA degradation pathway between Microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) Microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated Microcosms than untreated Microcosms. The Microcosm incubations and subsequent experiments with the Microcosm materials showed that AFO treatment resulted...
Kenneth Lee - One of the best experts on this subject based on the ideXlab platform.
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hydrocarbon biodegradation by arctic sea ice and sub ice microbial communities during Microcosm experiments northwest passage nunavut canada
FEMS Microbiology Ecology, 2016Co-Authors: Marieeve Garneau, Christine Michel, Guillaume Meisterhans, Nathalie Fortin, Thomas King, Charles W Greer, Kenneth LeeAbstract:The increasing accessibility to navigation and offshore oil exploration brings risks of hydrocarbon releases in Arctic waters. Bioremediation of hydrocarbons is a promising mitigation strategy but challenges remain, particularly due to low microbial metabolic rates in cold, ice-covered seas. Hydrocarbon degradation potential of ice-associated microbes collected from the Northwest Passage was investigated. Microcosm incubations were run for 15 days at -1.7°C with and without oil to determine the effects of hydrocarbon exposure on microbial abundance, diversity and activity, and to estimate component-specific hydrocarbon loss. Diversity was assessed with automated ribosomal intergenic spacer analysis and Ion Torrent 16S rRNA gene sequencing. Bacterial activity was measured by (3)H-leucine uptake rates. After incubation, sub-ice and sea-ice communities degraded 94% and 48% of the initial hydrocarbons, respectively. Hydrocarbon exposure changed the composition of sea-ice and sub-ice communities; in sea-ice Microcosms, Bacteroidetes (mainly Polaribacter) dominated whereas in sub-ice Microcosms, the contribution of Epsilonproteobacteria increased, and that of Alphaproteobacteria and Bacteroidetes decreased. Sequencing data revealed a decline in diversity and increases in Colwellia and Moritella in oil-treated Microcosms. Low concentration of dissolved organic matter (DOM) in sub-ice seawater may explain higher hydrocarbon degradation when compared to sea ice, where DOM was abundant and composed of labile exopolysaccharides.
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robust hydrocarbon degradation and dynamics of bacterial communities during nutrient enhanced oil spill bioremediation
Applied and Environmental Microbiology, 2002Co-Authors: Wilfred F M Roling, Michael G Milner, Martin D Jones, Kenneth Lee, Fabien Daniel, Richard J P Swannell, Ian M HeadAbstract:Degradation of oil on beaches is, in general, limited by the supply of inorganic nutrients. In order to obtain a more systematic understanding of the effects of nutrient addition on oil spill bioremediation, beach sediment Microcosms contaminated with oil were treated with different levels of inorganic nutrients. Oil biodegradation was assessed respirometrically and on the basis of changes in oil composition. Bacterial communities were compared by numerical analysis of denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified 16S rRNA genes and cloning and sequencing of PCR-amplified 16S rRNA genes. Nutrient amendment over a wide range of concentrations significantly improved oil degradation, confirming that N and P limited degradation over the concentration range tested. However, the extent and rate of oil degradation were similar for all Microcosms, indicating that, in this experiment, it was the addition of inorganic nutrients rather than the precise amount that was most important operationally. Very different microbial communities were selected in all of the Microcosms. Similarities between DGGE profiles of replicate samples from a single Microcosm were high (95% ± 5%), but similarities between DGGE profiles from replicate Microcosms receiving the same level of inorganic nutrients (68% ± 5%) were not significantly higher than those between Microcosms subjected to different nutrient amendments (63% ± 7%). Therefore, it is apparent that the different communities selected cannot be attributed to the level of inorganic nutrients present in different Microcosms. Bioremediation treatments dramatically reduced the diversity of the bacterial community. The decrease in diversity could be accounted for by a strong selection for bacteria belonging to the alkane-degrading Alcanivorax/Fundibacter group. On the basis of Shannon-Weaver indices, rapid recovery of the bacterial community diversity to preoiling levels of diversity occurred. However, although the overall diversity was similar, there were considerable qualitative differences in the community structure before and after the bioremediation treatments.
James F Holden - One of the best experts on this subject based on the ideXlab platform.
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hydrogen limitation and syntrophic growth among natural assemblages of thermophilic methanogens at deep sea hydrothermal vents
Frontiers in Microbiology, 2016Co-Authors: Begum D Topcuoglu, Lucy C Stewart, Hilary G Morrison, David A Butterfield, Julie A Huber, James F HoldenAbstract:Thermophilic methanogens are common autotrophs at hydrothermal vents, but their growth constraints and dependence on H2 syntrophy in situ are poorly understood. Between 2012 and 2015, methanogens and H2-producing heterotrophs were detected by growth at 80°C and 55°C at most diffuse (7-40°C) hydrothermal vent sites at Axial Seamount. Microcosm incubations of diffuse hydrothermal fluids at 80°C and 55°C demonstrated that growth of thermophilic and hyperthermophilic methanogens is primarily limited by H2 availability. Amendment of Microcosms with NH4+ generally had no effect on CH4 production. However, annual variations in abundance and CH4 production were observed in relation to the eruption cycle of the seamount. Microcosm incubations of hydrothermal fluids at 80°C and 55°C supplemented with tryptone and no added H2 showed CH4 production indicating the capacity in situ for methanogenic H2 syntrophy. 16S rRNA genes were found in 80°C Microcosms from H2-producing archaea and H2-consuming methanogens, but not for any bacteria. In 55°C Microcosms, sequences were found from the H2-producing bacteria and H2-consuming methanogens and sulfate-reducing bacteria. A co-culture of representative organisms showed that Thermococcus paralvinellae supported the syntrophic growth of Methanocaldococcus bathoardescens at 82°C and Methanothermococcus sp. strain BW11 at 60°C. The results demonstrate that modeling of subseafloor methanogenesis should focus primarily on H2 availability and temperature, and that thermophilic H2 syntrophy can support methanogenesis within natural microbial assemblages and may be an important energy source for thermophilic autotrophs in marine geothermal environments.
