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Zhang Z, Ali M, Tang Z, Sun Q, Wang Q, Liu X, Yin L, Yan S, Xu M, Coulon F, Song X. Unveiling complete natural reductive dechlorination mechanisms of chlorinated ethenes in groundwater: Insights from functional gene analysis. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:134034. [PMID: 38521036 DOI: 10.1016/j.jhazmat.2024.134034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/22/2024] [Accepted: 03/12/2024] [Indexed: 03/25/2024]
Abstract
Monitored natural attenuation (MNA) of chlorinated ethenes (CEs) has proven to be a cost-effective and environment-friendly approach for groundwater remediation. In this study, the complete dechlorination of CEs with formation of ethene under natural conditions, were observed at two CE-contaminated sites, including a pesticide manufacturing facility (PMF) and a fluorochemical plant (FCP), particularly in the deeply weathered bedrock aquifer at the FCP site. Additionally, a higher abundance of CE-degrading bacteria was identified with heightened dechlorination activities at the PMF site, compared to the FCP site. The reductive dehalogenase genes and Dhc 16 S rRNA gene were prevalent at both sites, even in groundwater where no CE dechlorination was observed. vcrA and bvcA was responsible for the complete dechlorination at the PMF and FCP site, respectively, indicating the distinct contributions of functional microbial species at each site. The correlation analyses suggested that Sediminibacterium has the potential to achieve the complete dechlorination at the FCP site. Moreover, the profiles of CE-degrading bacteria suggested that dechlorination occurred under Fe3+/sulfate-reducing and nitrate-reducing conditions at the PMF and FCP site, respectively. Overall these findings provided multi-lines of evidence on the diverse mechanisms of CE-dechlorination under natural conditions, which can provide valuable guidance for MNA strategies implementation.
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Affiliation(s)
- Zhuanxia Zhang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mukhtiar Ali
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiwen Tang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Sun
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Qing Wang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Xin Liu
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Lipu Yin
- China State Science Dingshi Environmental Engineering CO., LTD, Beijing, China
| | - Song Yan
- China State Science Dingshi Environmental Engineering CO., LTD, Beijing, China
| | - Minmin Xu
- Shandong Academy of Environmental Sciences Co., LTD, Jinan 250013, China
| | - Frederic Coulon
- School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
| | - Xin Song
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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2
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Zeng J, Wu R, Peng T, Li Q, Wang Q, Wu Y, Song X, Lin X. Low-temperature thermally enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soil: Effects on fate, toxicity and bacterial communities. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 335:122247. [PMID: 37482336 DOI: 10.1016/j.envpol.2023.122247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 07/25/2023]
Abstract
Remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using thermal desorption technology typically requires very high temperatures, necessitating coupled microbial treatment for energy and cost reduction. This study investigated the fate and toxicity of PAHs as well as the responses of microbial communities following thermal treatment within a low temperature range. The optimal temperature for PAH mineralization was 20-28 °C, within the growth range of most mesophilic microorganisms. By contrast, 50 °C treatment almost completely inhibited PAH mineralization but resulted in the greatest detoxification effect particularly for cardiotoxicity and nephrotoxicity. A potential increase in toxicity was observed at 28 °C. Co-metabolism and non-extractable residue formation may play an interdependent role in thermally enhanced bioremediation. Moreover, alterations in bacterial communities were strongly associated with PAH mineralization and zebrafish toxicity, revealing that soil microorganisms play a direct role in PAH mineralization and served as ecological receptors reflecting changes in toxicity. Network analysis revealed that Firmicutes formed specific ecological communities at high temperature, whereas Acidobacteria and Proteobacteria act as primary PAH degraders at moderate temperature. These findings will enable better integration of strategies for thermal and microbial treatments in soil remediation.
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Affiliation(s)
- Jun Zeng
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Ruini Wu
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Tingting Peng
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Qigang Li
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Qing Wang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Yucheng Wu
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Xin Song
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China
| | - Xiangui Lin
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71 Nanjing, 210008, China.
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3
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Hnatko JP, Liu C, Elsey JL, Dong S, Fortner JD, Pennell KD, Abriola LM, Cápiro NL. Microbial Reductive Dechlorination by a Commercially Available Dechlorinating Consortium Is Not Inhibited by Perfluoroalkyl Acids (PFAAs) at Field-Relevant Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37216485 DOI: 10.1021/acs.est.2c04815] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Perfluoroalkyl acids (PFAAs) have been shown to inhibit biodegradation (i.e., organohalide respiration) of chlorinated ethenes. The potential negative impacts of PFAAs on microbial species performing organohalide respiration, particularly Dehalococcoides mccartyi (Dhc), and the efficacy of in situ bioremediation are a critical concern for comingled PFAA-chlorinated ethene plumes. Batch reactor (no soil) and microcosm (with soil) experiments, containing a PFAA mixture and bioaugmented with KB-1, were completed to assess the impact of PFAAs on chlorinated ethene organohalide respiration. In batch reactors, PFAAs delayed complete biodegradation of cis-1,2-dichloroethene (cis-DCE) to ethene. Maximum substrate utilization rates (a metric for quantifying biodegradation rates) were fit to batch reactor experiments using a numerical model that accounted for chlorinated ethene losses to septa. Fitted values for cis-DCE and vinyl chloride biodegradation were significantly lower (p < 0.05) in batch reactors containing ≥50 mg/L PFAAs. Examination of reductive dehalogenase genes implicated in ethene formation revealed a PFAA-associated change in the Dhc community from cells harboring the vcrA gene to those harboring the bvcA gene. Organohalide respiration of chlorinated ethenes was not impaired in microcosm experiments with PFAA concentrations of 38.7 mg/L and less, suggesting that a microbial community containing multiple strains of Dhc is unlikely to be inhibited by PFAAs at lower, environmentally relevant concentrations.
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Affiliation(s)
- Jason P Hnatko
- Environmental Resources Management (ERM), Boston, Massachusetts 02108, United States
| | - Chen Liu
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Jack L Elsey
- Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Sheng Dong
- Department of Civil and Environmental Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - John D Fortner
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Kurt D Pennell
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Linda M Abriola
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Natalie L Cápiro
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
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Shi C, Tong M, Cai Q, Li Z, Li P, Lu Y, Cao Z, Liu H, Zhao HP, Yuan S. Electrokinetic-Enhanced Bioremediation of Trichloroethylene-Contaminated Low-Permeability Soils: Mechanistic Insight from Spatio-Temporal Variations of Indigenous Microbial Community and Biodehalogenation Activity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5046-5055. [PMID: 36926893 DOI: 10.1021/acs.est.3c00278] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Electrokinetic-enhanced bioremediation (EK-Bio), particularly bioaugmentation with injection of biodehalogenation functional microbes such as Dehalococcoides, has been documented to be effective in treating a low-permeability subsurface matrix contaminated with chlorinated ethenes. However, the spatio-temporal variations of indigenous microbial community and biodehalogenation activity of the background matrix, a fundamental aspect for understanding EK-Bio, remain unclear. To fill this gap, we investigated the variation of trichloroethylene (TCE) biodehalogenation activity in response to indigenous microbial community succession in EK-Bio by both column and batch experiments. For a 195 day EK-Bio column (∼1 V/cm, electrolyte circulation, lactate addition), biodehalogenation activity occurred first near the cathode (<60 days) and then spread to the anode (>90 days), which was controlled by electron acceptor (i.e., Fe(III)) competition and microbe succession. Amplicon sequencing and metagenome analysis revealed that iron-reducing bacteria (Geobacter, Anaeromyxobacter, Geothrix) were enriched within initial 60 d and were gradually replaced by organohalide-respiring bacteria (versatile Geobacter and obligate Dehalobacter) afterward. Iron-reducing bacteria required an initial long time to consume the competitive electron acceptors so that an appropriate reductive condition could be developed for the enrichment of organohalide-respiring bacteria and the enhancement of TCE biodehalogenation activity.
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Affiliation(s)
- Chongwen Shi
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Man Tong
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Qizheng Cai
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Zhengtao Li
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310030, P. R. China
| | - Ping Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Yuxi Lu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Zixuan Cao
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Hui Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - He-Ping Zhao
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310030, P. R. China
| | - Songhu Yuan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
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5
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May AL, Xie Y, Kara Murdoch F, Michalsen MM, Löffler FE, Campagna SR. Metabolome patterns identify active dechlorination in bioaugmentation consortium SDC-9™. Front Microbiol 2022; 13:981994. [PMID: 36386687 PMCID: PMC9641191 DOI: 10.3389/fmicb.2022.981994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/22/2022] [Indexed: 12/01/2023] Open
Abstract
Ultra-high performance liquid chromatography-high-resolution mass spectrometry (UPHLC-HRMS) is used to discover and monitor single or sets of biomarkers informing about metabolic processes of interest. The technique can detect 1000's of molecules (i.e., metabolites) in a single instrument run and provide a measurement of the global metabolome, which could be a fingerprint of activity. Despite the power of this approach, technical challenges have hindered the effective use of metabolomics to interrogate microbial communities implicated in the removal of priority contaminants. Herein, our efforts to circumvent these challenges and apply this emerging systems biology technique to microbiomes relevant for contaminant biodegradation will be discussed. Chlorinated ethenes impact many contaminated sites, and detoxification can be achieved by organohalide-respiring bacteria, a process currently assessed by quantitative gene-centric tools (e.g., quantitative PCR). This laboratory study monitored the metabolome of the SDC-9™ bioaugmentation consortium during cis-1,2-dichloroethene (cDCE) conversion to vinyl chloride (VC) and nontoxic ethene. Untargeted metabolomics using an UHPLC-Orbitrap mass spectrometer and performed on SDC-9™ cultures at different stages of the reductive dechlorination process detected ~10,000 spectral features per sample arising from water-soluble molecules with both known and unknown structures. Multivariate statistical techniques including partial least squares-discriminate analysis (PLSDA) identified patterns of measurable spectral features (peak patterns) that correlated with dechlorination (in)activity, and ANOVA analyses identified 18 potential biomarkers for this process. Statistical clustering of samples with these 18 features identified dechlorination activity more reliably than clustering of samples based only on chlorinated ethene concentration and Dhc 16S rRNA gene abundance data, highlighting the potential value of metabolomic workflows as an innovative site assessment and bioremediation monitoring tool.
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Affiliation(s)
- Amanda L. May
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, United States
| | - Yongchao Xie
- Department of Civil and Environmental Engineering, Tickle College of Engineering, University of Tennessee, Knoxville, TN, United States
| | - Fadime Kara Murdoch
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, United States
| | - Mandy M. Michalsen
- Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS, United States
| | - Frank E. Löffler
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, United States
- Department of Civil and Environmental Engineering, Tickle College of Engineering, University of Tennessee, Knoxville, TN, United States
- Department of Microbiology, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States
- Department of Biosystems Engineering and Soil Science, Herbert College of Agriculture, The University of Tennessee, Knoxville, TN, United States
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Shawn R. Campagna
- Department of Chemistry, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States
- Biological and Small Molecule Mass Spectrometry Core, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States
- University of Tennessee-Oak Ridge Innovation Institute, University of Tennessee, Knoxville, TN, United States
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6
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Hudari MSB, Richnow H, Vogt C, Nijenhuis I. Mini-review: effect of temperature on microbial reductive dehalogenation of chlorinated ethenes: a review. FEMS Microbiol Ecol 2022; 98:6638985. [PMID: 35810002 DOI: 10.1093/femsec/fiac081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 06/30/2022] [Accepted: 07/07/2022] [Indexed: 11/13/2022] Open
Abstract
Temperature is a key factor affecting microbial activity and ecology. An increase in temperature generally increases rates of microbial processes up to a certain threshold, above which rates decline rapidly. In the subsurface, temperature of groundwater is usually stable and related to the annual average temperature at the surface. However, anthropogenic activities related to the use of the subsurface, e.g. for thermal heat management, foremost heat storage, will affect the temperature of groundwater locally. This mini-review intends to summarize the current knowledge on reductive dehalogenation activities of the chlorinated ethenes, common urban groundwater contaminants, at different temperatures. This includes an overview of activity and dehalogenation extent at different temperatures in laboratory isolates and enrichment cultures, the effect of shifts in temperature in micro- and mesocosm studies as well as observed biotransformation at different natural and induced temperatures at contaminated field sites. Furthermore, we address indirect effects on biotransformation, e.g. changes in fermentation, methanogenesis and sulfate reduction as competing or synergetic microbial processes. Finally, we address the current gaps in knowledge regarding bioremediation of chlorinated ethenes, microbial community shifts and bottlenecks for active combination with thermal energy storage, and necessities for bioaugmentation and/or natural re-populations after exposure to high temperature.
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Affiliation(s)
- Mohammad Sufian Bin Hudari
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Hans Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Ivonne Nijenhuis
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
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7
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Wang Q, Guo S, Ali M, Song X, Tang Z, Zhang Z, Zhang M, Luo Y. Thermally enhanced bioremediation: A review of the fundamentals and applications in soil and groundwater remediation. JOURNAL OF HAZARDOUS MATERIALS 2022; 433:128749. [PMID: 35364527 DOI: 10.1016/j.jhazmat.2022.128749] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/11/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
Thermally enhanced bioremediation (TEB), a new concept proposed in recent years, explores the combination of thermal treatment and bioremediation to address the challenges of the low efficiency and long duration of bioremediation. This study presented a comprehensive review regarding the fundamentals of TEB and its applications in soil and groundwater remediation. The temperature effects on the bioremediation of contaminants were systematically reviewed. The thermal effects on the physical, chemical and biological characteristics of soil, and the corresponding changes of contaminants bioavailability and microbial metabolic activities were summarized. Specifically, the increase in temperature within a suitable range can proliferate enzymes enrichment, extracellular polysaccharides and biosurfactants production, and further enhancing bioremediation. Furthermore, a systematic evaluation of TEB applications by utilizing traditional in situ heating technologies, as well as renewable energy (e.g., stored aquifer thermal energy and solar energy), was provided. Additionally, TEB has been applied as a biological polishing technology post thermal treatment, which can be a cost-effective method to address the contaminants rebounds in groundwater remediation. However, there are still various challenges to be addressed in TEB, and future research perspectives to further improve the basic understanding and applications of TEB for the remediation of contaminated soil and groundwater are presented.
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Affiliation(s)
- Qing Wang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Siwei Guo
- Zhejiang University, Hangzhou, China
| | - Mukhtiar Ali
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Song
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Zhiwen Tang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuanxia Zhang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meng Zhang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Yongming Luo
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
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Koproch N, Dahmke A, Schwardt A, Köber R. Temperature influence on the NAPL-water interfacial area between 10 °C and 60 °C for trichloroethylene. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 245:103932. [PMID: 34952400 DOI: 10.1016/j.jconhyd.2021.103932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 10/07/2021] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Underground thermal energy storage (UTES) can contribute to renewable energy usability, especially in urban areas with the most demand and available infrastructure. But UTES may interact in those areas with non-aqueous phase liquids (NAPL) by increasing the temperature in storage formations. To determine temperature effects on NAPL dissolution rates into groundwater, the effective specific interfacial area (anw) between trichloroethylene (TCE) and water, as a function of temperature and TCE pore saturations, was calculated. The interfacial tension between the flushing solution and the NAPL, the adsorption coefficient and the retardation of a reactive tracer were determined by the drop weight method and interfacial tracer tests at 10 °C, 30 °C and 60 °C. From 10 to 60 °C anw increased by a factor of six to eight. Based on the results, a function to describe the anw between TCE and water was developed, which could improve numerical models on NAPL dissolution rates. The main mechanisms for the increase in anw are suggested to be NAPL blob migration on pore scale, and thermal-induced changes in wettability and in blob shape correlating with a temperature-induced decline in effective porosity of up to 32%. These results contribute to the understanding and predictability of UTES in contaminated aquifers, the general response of NAPL behavior on artificial increasing aquifer temperatures and the improvement of thermal and other groundwater remediation techniques.
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Affiliation(s)
- Nicolas Koproch
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118 Kiel, Germany.
| | - Andreas Dahmke
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118 Kiel, Germany
| | - Alexander Schwardt
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118 Kiel, Germany
| | - Ralf Köber
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118 Kiel, Germany
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9
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Yamazaki Y, Kitamura G, Tian X, Suzuki I, Kobayashi T, Shimizu T, Inoue D, Ike M. Temperature dependence of sequential chlorinated ethenes dechlorination and the dynamics of dechlorinating microorganisms. CHEMOSPHERE 2022; 287:131989. [PMID: 34450366 DOI: 10.1016/j.chemosphere.2021.131989] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
Thermally enhanced bioremediation is a promising approach to shorten the bioremediation period of tetrachloroethene (PCE) and trichloroethene (TCE). To clarify the influence that temperature has on stepwise PCE dechlorination and associated microorganisms, this study conducted dechlorination experiments using contaminated soil and groundwater under five distinct temperature conditions (i.e., 15, 20, 25, 30, and 35 °C). PCE and TCE were dechlorinated most rapidly at 25-35 °C, whereas the preferable temperatures for the dechlorination of cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC) were 25-30 °C and 25 °C, respectively. Microbial community analysis revealed that Sulfurospirillum and Geobacter may have a dominant contribution to the dechlorination of PCE to cis-1,2-DCE, whereas Dehalococcoides harboring VC reductase genes are likely major contributors to the dechlorination of cis-1,2-DCE and VC. These results suggest that temperature influences various microbial groups, including major dechlorinating microorganisms, resulting in the different extent of PCE dechlorination. In addition, the microbial community structure greatly changed after the onset of the experiment, whereas the temperature influence of 15-30 °C on the microbial community structure was minor; however, the microbial community was significantly impacted at 35 °C. Collectively, these results suggest that thermally enhanced anaerobic dechlorination at 25 °C is useful for successful dechlorination of chlorinated ethenes in a short period.
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Affiliation(s)
- Yuji Yamazaki
- Research & Development Institute, TAKENAKA Corporation, 1-5-1 Otsuka, Inzai, Chiba, Japan; Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan.
| | - Gaku Kitamura
- Research & Development Institute, TAKENAKA Corporation, 1-5-1 Otsuka, Inzai, Chiba, Japan
| | - Xiaowei Tian
- Center for Creation of Symbiosis Society with Risk, Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, Japan
| | - Ichiro Suzuki
- Department of Chemistry and Life Science, Graduate School of Engineering Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, Japan
| | - Takeshi Kobayashi
- Division of Artificial Environment and Information Research, Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, Japan
| | - Takaaki Shimizu
- Technical Headquarters, TAKENAKA Corporation, 1-1-1 Shinsuna, Koto-ku, Tokyo, Japan
| | - Daisuke Inoue
- Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan
| | - Michihiko Ike
- Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan
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Yang K, Zhao Y, Ji M, Li Z, Zhai S, Zhou X, Wang Q, Wang C, Liang B. Challenges and opportunities for the biodegradation of chlorophenols: Aerobic, anaerobic and bioelectrochemical processes. WATER RESEARCH 2021; 193:116862. [PMID: 33550168 DOI: 10.1016/j.watres.2021.116862] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 01/17/2021] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Chlorophenols (CPs) are highly toxic and refractory contaminants which widely exist in various environments and cause serious harm to human and environment health and safety. This review provides comprehensive information on typical CPs biodegradation technologies, the most green and benign ones for CPs removal. The known aerobic and anaerobic degradative bacteria, functional enzymes, and metabolic pathways of CPs as well as several improving methods and critical parameters affecting the overall degradation efficiency are systematically summarized and clarified. The challenges for CPs mineralization are also discussed, mainly including the dechlorination of polychlorophenols (poly-CPs) under aerobic condition and the ring-cleavage of monochlorophenols (MCPs) under anaerobic condition. The coupling of functional materials and degraders as well as the operation of sequential anaerobic-aerobic bioreactors and bioelectrochemical system (BES) are promising strategies to overcome some current limitations. Future perspective and research gaps in this field are also proposed, including the further understanding of microbial information and the specific role of materials in CPs biodegradation, the potential application of innovative biotechnologies and new operating modes to optimize and maximize the function of the system, and the scale-up of bioreactors towards the efficient biodegradation of CPs.
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Affiliation(s)
- Kaichao Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Yingxin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China.
| | - Min Ji
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Zhiling Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Siyuan Zhai
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xu Zhou
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Qian Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Can Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Bin Liang
- School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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Bin Hudari MS, Vogt C, Richnow HH. Effect of Temperature on Acetate Mineralization Kinetics and Microbial Community Composition in a Hydrocarbon-Affected Microbial Community During a Shift From Oxic to Sulfidogenic Conditions. Front Microbiol 2021; 11:606565. [PMID: 33391229 PMCID: PMC7773710 DOI: 10.3389/fmicb.2020.606565] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/23/2020] [Indexed: 01/04/2023] Open
Abstract
Aquifer thermal energy storage (ATES) allows for the seasonal storage and extraction of heat in the subsurface thus reducing reliance on fossil fuels and supporting decarbonization of the heating and cooling sector. However, the impacts of higher temperatures toward biodiversity and ecosystem services in the subsurface environment remain unclear. Here, we conducted a laboratory microcosm study comprising a hydrocarbon-degrading microbial community from a sulfidic hydrocarbon-contaminated aquifer spiked with 13C-labeled acetate and incubated at temperatures between 12 and 80°C to evaluate (i) the extent and rates of acetate mineralization and (ii) the resultant temperature-induced shifts in the microbial community structure. We observed biphasic mineralization curves at 12, 25, 38, and 45°C, arising from immediate and fast aerobic mineralization due to an initial oxygen exposure, followed by slower mineralization at sulfidogenic conditions. At 60°C and several replicates at 45°C, acetate was only aerobically mineralized. At 80°C, no mineralization was observed within 178 days. Rates of acetate mineralization coupled to sulfate reduction at 25 and 38°C were six times faster than at 12°C. Distinct microbial communities developed in oxic and strictly anoxic phases of mineralization as well as at different temperatures. Members of the Alphaproteobacteria were dominant in the oxic mineralization phase at 12–38°C, succeeded by a more diverse community in the anoxic phase composed of Deltaproteobacteria, Clostridia, Spirochaetia, Gammaproteobacteria and Anaerolinea, with varying abundances dependent on the temperature. In the oxic phases at 45 and 60°C, phylotypes affiliated to spore-forming Bacilli developed. In conclusion, temperatures up to 38°C allowed aerobic and anaerobic acetate mineralization albeit at varying rates, while mineralization occurred mainly aerobically between 45 and 60°C; thermophilic sulfate reducers being active at temperatures > 45°C were not detected. Hence, temperature may affect dissolved organic carbon mineralization rates in ATES while the variability in the microbial community composition during the transition from micro-oxic to sulfidogenic conditions highlights the crucial role of electron acceptor availability when combining ATES with bioremediation.
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Affiliation(s)
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Hans Hermann Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Leipzig, Germany
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Tang S, Song X, Wang Q, Wang S. Effects of two surfactants on microbial diversity of a PCE-degrading microbial consortium. CHEMOSPHERE 2020; 261:127685. [PMID: 32771713 DOI: 10.1016/j.chemosphere.2020.127685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 06/23/2020] [Accepted: 07/11/2020] [Indexed: 06/11/2023]
Abstract
The effects of two representative surfactants, Rhamnolipids and Tween 80, on the microbial diversity of a PCE-degrading consortium during surfactant-enhanced biodegradation, were explored. The biodegradation efficiency was increased from 47.25% to 73.44%, and 47.25%-66.69%, with the addition of Rhamnolipid at 10 mg/L and Tween 80 at 50 mg/L, respectively. PCE biodegradation kinetics can be described by the pseudo-first-order reaction model for both scenarios. Analyses of alpha and beta indices of the microbial consortium showed that the microbial diversity of both groups exposed to either surfactant was not significantly different from the PCE only group. However, the bacterial abundance in the consortium changed significantly at both the phylum and genus levels. The results demonstrated that the composition of the PCE-degrading consortium is relatively stable, but the exposure to both surfactants results in the enrichment of some genera, which could contribute to the increased biodegradation efficiency.
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Affiliation(s)
- Shiyue Tang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xin Song
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Nanjing, 210008, China
| | - Qing Wang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Nanjing, 210008, China; National Engineering Laboratory for Site Remediation Technologies, Beijing, 100015, China.
| | - Shui Wang
- Jiangsu Provincial Academy of Environmental Science, 176 North Jiangdong Road, Nanjing, Jiangsu 210036, China
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Waseem H, Ali J, Syed JH, Jones KC. Establishing the relationship between molecular biomarkers and biotransformation rates: Extension of knowledge for dechlorination of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 263:114676. [PMID: 33618452 DOI: 10.1016/j.envpol.2020.114676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/20/2020] [Accepted: 04/24/2020] [Indexed: 06/12/2023]
Abstract
Anaerobic reductive treatment technologies offer cost-effective and large-scale treatment of chlorinated compounds, including polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs). The information about the degradation rates of these compounds in natural settings is critical but difficult to obtain because of slow degradation processes. Establishing a relationship between biotransformation rate and abundance of biomarkers is one of the most critical challenges faced by the bioremediation industry. When solved for a given contaminant, it may result in significant cost savings because of serving as a basis for action. In the current review, we have summarized the studies highlighting the use of biomarkers, particularly DNA and RNA, as a proxy for reductive dechlorination of chlorinated ethenes. As the use of biomarkers for predicting biotransformation rates has not yet been executed for PCDD/Fs, we propose the extension of the same knowledge for dioxins, where slow degradation rates further necessitate the need for developing the biomarker-rate relationship. For this, we have first retrieved and calculated the bioremediation rates of different PCDD/Fs and then highlighted the key sequences that can be used as potential biomarkers. We have also discussed the implications and hurdles in developing such a relationship. Improvements in current techniques and collaboration with some other fields, such as biokinetic modeling, can improve the predictive capability of the biomarkers so that they can be used for effectively predicting biotransformation rates of dioxins and related compounds. In the future, a valid and established relationship between biomarkers and biotransformation rates of dioxin may result in significant cost savings, whilst also serving as a basis for action.
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Affiliation(s)
- Hassan Waseem
- Department of Civil & Environmental Engineering, Michigan State University, East Lansing, MI, 48823, USA; Department of Biotechnology, University of Sialkot, Sialkot, Punjab 51310, Pakistan
| | - Jafar Ali
- Key Laboratory of Environmental Nanotechnology and Health Effects, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing, 100085, China
| | - Jabir Hussain Syed
- Department of Meteorology, COMSATS University, Tarlai Kalan Park Road, Islamabad, 45550, Pakistan.
| | - Kevin C Jones
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
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Targeted detection of Dehalococcoides mccartyi microbial protein biomarkers as indicators of reductive dechlorination activity in contaminated groundwater. Sci Rep 2019; 9:10604. [PMID: 31332202 PMCID: PMC6646388 DOI: 10.1038/s41598-019-46901-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/10/2019] [Indexed: 12/15/2022] Open
Abstract
Dehalococcoides mccartyi (Dhc) bacterial strains expressing active reductive dehalogenase (RDase) enzymes play key roles in the transformation and detoxification of chlorinated pollutants, including chlorinated ethenes. Site monitoring regimes traditionally rely on qPCR to assess the presence of Dhc biomarker genes; however, this technique alone cannot directly inform about dechlorination activity. To supplement gene-centric approaches and provide a more reliable proxy for dechlorination activity, we sought to demonstrate a targeted proteomics approach that can characterize Dhc mediated dechlorination in groundwater contaminated with chlorinated ethenes. Targeted peptide selection was conducted in axenic cultures of Dhc strains 195, FL2, and BAV1. These experiments yielded 37 peptides from housekeeping and structural proteins (i.e., GroEL, EF-TU, rpL7/L2 and the S-layer), as well as proteins involved in the reductive dechlorination activity (i.e., FdhA, TceA, and BvcA). The application of targeted proteomics to a defined bacterial consortium and contaminated groundwater samples resulted in the detection of FdhA peptides, which revealed active dechlorination with Dhc strain-level resolution, and the detection of RDases peptides indicating specific reductive dechlorination steps. The results presented here show that targeted proteomics can be applied to groundwater samples and provide protein level information about Dhc dechlorination activity.
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15
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Koproch N, Dahmke A, Köber R. The aqueous solubility of common organic groundwater contaminants as a function of temperature between 5 and 70 °C. CHEMOSPHERE 2019; 217:166-175. [PMID: 30415115 DOI: 10.1016/j.chemosphere.2018.10.153] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 10/13/2018] [Accepted: 10/21/2018] [Indexed: 06/09/2023]
Abstract
High-temperature thermal energy storage in shallow aquifers can potentially increase ambient groundwater temperatures up to 70 °C or even more. Since an increase in temperature is expected to influence contaminant mass flux into groundwater monitoring the spreading of organic contaminants located in the subsurface is crucial. In numerous former studies, the NAPL solubility, one major parameter controlling mass flux on field scale, was measured at temperatures up to 70 °C for a broad spectrum of organic substances. However, quantitative calculations of solubilities as a function of temperature considering a compiled database are largely missing. Aiming to examine the reliability of existing solubility-temperature relationships, to describe them functionally and further to identify knowledge gaps, previously published data on solubilities of 42 different organic groundwater contaminants were evaluated in this study. By using a common temperature regression function, the calculated solubility curves from compiled solubility data for 5-70 °C show relative changes between a few percent (CHCs and BTEX) and up to 2000% (PAHs). As published temperature-dependent solubilities for chlorinated ethylenes are contradictory in parts, solubilities of tetrachloroethylene, trichloroethylene, 1,2-cis-dichloroethylene and 1,2-trans-dichloroethylene were additionally investigated in more detail using batch experiments between 5 and 70 °C. The results show distinctive solubility minima at medium temperatures (20-40 °C) with concentrations decreasing from 5 °C to the minimum by 10-20%. The measured and calculated temperature-dependent solubilities enable a more reliable assessment of thermal energy storage at contaminated sites, of existing thermal remediation approaches and of combinations of underground heat storage with groundwater remediation.
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Affiliation(s)
- Nicolas Koproch
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118, Kiel, Germany.
| | - Andreas Dahmke
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118, Kiel, Germany
| | - Ralf Köber
- University of Kiel, Applied Geosciences, Ludewig-Meyn Straße 10, 24118, Kiel, Germany
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Han K, Park S, Hong U, Yeum Y, Kwon S, Kim Y. Estimating bioaugmentation efficacy of TCE dechlorination using long-term field well-to-well tests in a highly recharged and TCE-contaminated aquifer. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2019; 54:208-218. [PMID: 30600760 DOI: 10.1080/10934529.2018.1544800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/26/2018] [Accepted: 10/31/2018] [Indexed: 06/09/2023]
Abstract
This study demonstrates a combined field method accurately assessing the extent of trichloroethylene (TCE) reductive dechlorination activity and the mass fraction of its by-products. A combined method of injecting a known concentration of 1,1,2-trichloro-2-fluoroethene (TCFE) as a TCE bio-surrogate and a data processing technique of forced mass balance (FMB), considering the sorption effect on the mass fraction of chloroethene was evaluated by performing soil column and field bioaugmentation tests. In the soil column test, the FMB resulted in the mass fraction of 6% TCE, 48.3% cis-1,2-dichloroethene, 18.5% vinyl chloride and 27.2% ethylene. In the field bioaugmentation test, TCFE showed equivalent dechlorination pathways of TCE. The mass fractions estimated by FMB were very similar to those observed in the soil column bioaugmentation tests: 4.5% TCFE, 57.1% 1,2-dichloro-1-fluoroethene, 12% 1-chloro-1-fluoroethene and 26.4% fluoroethene (FE). The FMB method gave ∼50% higher mass fraction for more chlorinated ethenes (i.e., TCFE) and ∼10% lower mass fraction of less chlorinated ethenes (i.e., FE) than those considering only the aqueous concentrations of chlorofluoroethenes. A combined method of TCFE and FMB that could accurately estimate both the extent of dechlorination activities and mass distribution of TCE reductive dechlorination would be highly useful.
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Affiliation(s)
- Kyungjin Han
- a Department of Environmental Engineering , Korea University , Sejong , Korea
| | - Sunhwa Park
- b National Institute of Environmental Research , Incheon , Korea
| | | | - Yuhoon Yeum
- d Program in Environmental Technology and Policy , Korea University , Sejong , Korea
| | - Sooyoul Kwon
- e Department of Environmental Health , Korea National Open University , Seoul , Korea
| | - Young Kim
- a Department of Environmental Engineering , Korea University , Sejong , Korea
- d Program in Environmental Technology and Policy , Korea University , Sejong , Korea
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17
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Abstract
Organohalide respiration (OHR) is an anaerobic metabolism by which bacteria conserve energy with the use of halogenated compounds as terminal electron acceptors. Genes involved in OHR are organized in reductive dehalogenase (rdh) gene clusters and can be found in relatively high copy numbers in the genomes of organohalide-respiring bacteria (OHRB). The minimal rdh gene set is composed by rdhA and rdhB, encoding the catalytic enzyme involved in reductive dehalogenation and its putative membrane anchor, respectively. In this chapter, we present the major findings concerning the regulatory strategies developed by OHRB to control the expression of the rdh gene clusters. The first section focuses on the description of regulation patterns obtained from targeted transcriptional analyses, and from transcriptomic and proteomic studies, while the second section offers a detailed overview of the biochemically characterized OHR regulatory proteins identified so far. Depending on OHRB, transcriptional regulators belonging to three different protein families are found in the direct vicinity of rdh gene clusters, suggesting that they activate the transcription of their cognate gene cluster. In this chapter, strong emphasis was laid on the family of CRP/FNR-type RdhK regulators which belong to members of the genera Dehalobacter and Desulfitobacterium. Whereas only chlorophenols have been identified as effectors for RdhK regulators, the protein sequence diversity suggests a broader organohalide spectrum. Thus, effector identification of new regulators offers a promising alternative to elucidate the substrates of yet uncharacterized reductive dehalogenases. Future work investigating the possible cross-talk between OHR regulators and their possible use as biosensors is discussed.
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Marcet TF, Cápiro NL, Yang Y, Löffler FE, Pennell KD. Impacts of low-temperature thermal treatment on microbial detoxification of tetrachloroethene under continuous flow conditions. WATER RESEARCH 2018; 145:21-29. [PMID: 30114555 DOI: 10.1016/j.watres.2018.07.076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 07/20/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
Coupling in situ thermal treatment (ISTT) with microbial reductive dechlorination (MRD) has the potential to enhance contaminant degradation and reduce cleanup costs compared to conventional standalone remediation technologies. Impacts of low-temperature ISTT on Dehalococcoides mccartyi (Dhc), a relevant species in the anaerobic degradation of cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) to nontoxic ethene, were assessed in sand-packed columns under dynamic flow conditions. Dissolved tetrachloroethene (PCE; 258 ± 46 μM) was introduced to identical columns bioaugmented with the PCE-to-ethene dechlorinating consortium KB-1®. Initial column temperatures represented a typical aquifer (15 °C) or a site undergoing low-temperature ISTT (35 °C), and were subsequently increased to 35 and 74 °C, respectively, to assess temperature impacts on reductive dechlorination activity. In the 15 °C column, PCE was transformed primarily to cis-DCE (159 ± 2 μM), which was further degraded to VC (164 ± 3 μM) and ethene (30 ± 0 μM) within 17 pore volumes (PVs) after the temperature was increased to 35 °C. Regardless of the initial column temperature, ethene constituted >50 mol% of effluent degradation products in both columns after 73-74 PVs at 35 °C, indicating that MRD performance was greatly improved under low-temperature ISTT conditions. Increasing the temperature of the column initially at 35 °C resulted in continued VC and ethene production until a temperature of approximately 43 °C was reached, at which point Dhc activity substantially decreased. The abundance of the vcrA reductive dehalogenase gene exceeded that of the bvcA gene by 1-2.5 orders of magnitude at 15 °C, but this relationship inversed at temperatures >35 °C, suggesting Dhc strain-specific responses to temperature. These findings demonstrate improved MRD performance with low-temperature thermal treatment and emphasize potential synergistic effects at sites undergoing ISTT.
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Affiliation(s)
- Tyler F Marcet
- Department of Civil and Environmental Engineering, Tufts University, Medford, MA 02155, United States
| | - Natalie L Cápiro
- Department of Civil and Environmental Engineering, Tufts University, Medford, MA 02155, United States.
| | - Yi Yang
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, United States
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, United States; Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States; Department of Biosystems Engineering & Soil Science, University of Tennessee, Knoxville, TN 37996, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996, United States; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Kurt D Pennell
- Department of Civil and Environmental Engineering, Tufts University, Medford, MA 02155, United States; School of Engineering, Brown University, Providence, RI 02912, United States.
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Yang Y, Cápiro NL, Yan J, Marcet TF, Pennell KD, Löffler FE. Resilience and recovery of Dehalococcoides mccartyi following low pH exposure. FEMS Microbiol Ecol 2017; 93:4411799. [DOI: 10.1093/femsec/fix130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/05/2017] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yi Yang
- Department of Civil and Environmental Engineering, University of Tennessee, 325 John D. Tickle Bldg, 851 Neyland Drive, Knoxville, TN 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Natalie L. Cápiro
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Jun Yan
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Department of Microbiology, University of Tennessee, M409 Walters Life Science Bldg, Knoxville, TN 37996, USA
| | - Tyler F. Marcet
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Kurt D. Pennell
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Frank E. Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, 325 John D. Tickle Bldg, 851 Neyland Drive, Knoxville, TN 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
- Department of Microbiology, University of Tennessee, M409 Walters Life Science Bldg, Knoxville, TN 37996, USA
- Department of Biosystems Engineering and Soil Science, University of Tennessee, 2506 E.J. Chapman Dr., Knoxville, TN 37996, USA
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Smith BJ, Boothe MA, Fiddler BA, Lozano TM, Rahi RK, Krzmarzick MJ. Enumeration of Organohalide Respirers in Municipal Wastewater Anaerobic Digesters. Microbiol Insights 2015; 8:9-14. [PMID: 26508873 PMCID: PMC4607082 DOI: 10.4137/mbi.s31445] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/10/2015] [Accepted: 09/15/2015] [Indexed: 01/01/2023] Open
Abstract
Organohalide contaminants such as triclosan and triclocarban have been well documented in municipal wastewater treatment plants (WWTPs), but the degradation of these contaminants is not well understood. One possible removal mechanism is organohalide respiration by which bacteria reduce the halogenated compound. The purpose of this study was to determine the abundance of organohalide-respiring bacteria in eight WWTP anaerobic digesters. The obligate organohalide respiring Dehalococcoides mccartyi was the most abundant and averaged 3.3 × 107 copies of 16S rRNA genes per gram, while the Dehalobacter was much lower at 2.6 × 104 copies of 16S rRNA genes per gram. The genus Sulfurospirillum spp. was also detected at 1.0 × 107 copies of 16S rRNA genes per gram. No other known or putatively organohalide-respiring strains in the Dehalococcoidaceae family were found to be present nor were the genera Desulfitobacterium or Desulfomonile.
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Affiliation(s)
- Bryan Jk Smith
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
| | - Melissa A Boothe
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
| | - Brice A Fiddler
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
| | - Tania M Lozano
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
| | - Russel K Rahi
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
| | - Mark J Krzmarzick
- School of Civil and Environmental Engineering, College of Engineering, Architecture and Technology, Oklahoma State University, Stillwater, OK, USA
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21
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Danko AS, Fontenete SJ, de Aquino Leite D, Leitão PO, Almeida C, Schaefer CE, Vainberg S, Steffan RJ, Azevedo NF. Detection of Dehalococcoides spp. by peptide nucleic acid fluorescent in situ hybridization. J Mol Microbiol Biotechnol 2014; 24:142-9. [PMID: 24970105 DOI: 10.1159/000362790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Chlorinated solvents including tetrachloroethene (perchloroethene and trichloroethene), are widely used industrial solvents. Improper use and disposal of these chemicals has led to a widespread contamination. Anaerobic treatment technologies that utilize Dehalococcoides spp. can be an effective tool to remediate these contaminated sites. Therefore, the aim of this study was to develop, optimize and validate peptide nucleic acid (PNA) probes for the detection of Dehalococcoides spp. in both pure and mixed cultures. PNA probes were designed by adapting previously published DNA probes targeting the region of the point mutations described for discriminating between the Dehalococcoides spp. strain CBDB1 and strain 195 lineages. Different fixation, hybridization and washing procedures were tested. The results indicated that the PNA probes hybridized specifically and with a high sensitivity to their corresponding lineages, and that the PNA probes developed during this work can be used in a duplex assay to distinguish between strain CBDB1 and strain 195 lineages, even in complex mixed cultures. This work demonstrates the effectiveness of using PNA fluorescence in situ hybridization to distinguish between two metabolically and genetically distinct Dehalococcoides strains, and they can have strong implications in the monitoring and differentiation of Dehalococcoides populations in laboratory cultures and at contaminated sites.
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Affiliation(s)
- Anthony S Danko
- Centro de Investigação em Geo-Ambiente e Recursos (CIGAR), Departamento de Engenharia de Minas, Faculdade de Engenharia, Porto, Portugal
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Zhen H, Du S, Rodenburg LA, Mainelis G, Fennell DE. Reductive dechlorination of 1,2,3,7,8-pentachlorodibenzo-p-dioxin and Aroclor 1260, 1254 and 1242 by a mixed culture containing Dehalococcoides mccartyi strain 195. WATER RESEARCH 2014; 52:51-62. [PMID: 24462927 DOI: 10.1016/j.watres.2013.12.038] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 12/16/2013] [Accepted: 12/27/2013] [Indexed: 06/03/2023]
Abstract
A mixed culture containing Dehalococcoides mccartyi strain 195 dechlorinated 1,2,3,7,8-pentachlorodibenzo-p-dioxin (1,2,3,7,8-PeCDD) and selected polychlorinated biphenyl (PCB) congeners in Aroclors 1260, 1254 and 1242. 1,2,3,7,8-PeCDD was dechlorinated to 1,3,7-trichlorodibenzo-p-dioxin (1,3,7-TrCDD) and/or 1,3,8-TrCDD via 1,3,7,8-tetrachlorodibenzo-p-dioxin (1,3,7,8-TeCDD), a pathway that excludes the production of the toxic congener 2,3,7,8-TeCDD. Dechlorination rate and extent was greatly enhanced by the addition of 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB) as an alternate halogenated substrate and/or incubation temperature increase from 25 °C to 35 °C. The most extensive dechlorination of PCBs occurred for Aroclor 1260 with 13 major congeners making up 44.1 mol% of the original PCBs dechlorinated by 42% over 250 days at 25 °C. When 1,2,3,4-TeCB was amended as co-substrate, the extent of dechlorination increased to 82%, over 250 days. The mixed culture primarily dechlorinated the doubly-flanked chlorines on 2,3,4-, 2,3,4,6-, and 2,3,4,5,6-substituted chlorophenyl rings, whereas it primarily removed the doubly-flanked para chlorine from the 2,3,4,5-substituted chlorophenyl ring. Experiments using a 20% dilution of culture with 31.8 μg/mL 1,2,3,4-TeCDD or 2,3,4,4',5-pentachlorobiphenyl (PCB 114) as sole halogenated substrate exhibited less than 0.1 mol% dechlorination over 120 days. Further, dechlorination of PCBs and PCDDs by the fully grown culture in the absence of 1,2,3,4-TeCB eventually stopped or greatly slowed over the incubation period. Since Dehalococcoides spp. only gain energy for growth from organohalide respiration, absence of reductive dechlorination upon transfer and dilution or cessation of dechlorination after long incubation times suggest that it is unlikely that strain 195 can grow using the PCDDs or PCBs utilized in this study.
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Affiliation(s)
- Huajun Zhen
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Songyan Du
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Lisa A Rodenburg
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Gediminas Mainelis
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Donna E Fennell
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA.
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Identification and environmental distribution of dcpA, which encodes the reductive dehalogenase catalyzing the dichloroelimination of 1,2-dichloropropane to propene in organohalide-respiring chloroflexi. Appl Environ Microbiol 2013; 80:808-18. [PMID: 24242248 DOI: 10.1128/aem.02927-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dehalococcoides mccartyi strains KS and RC grow with 1,2-dichloropropane (1,2-D) as an electron acceptor in enrichment cultures derived from hydrocarbon-contaminated and pristine river sediments, respectively. Transcription, expression, enzymatic, and PCR analyses implicated the reductive dehalogenase gene dcpA in 1,2-D dichloroelimination to propene and inorganic chloride. Quantitative real-time PCR (qPCR) analyses demonstrated a D. mccartyi cell increase during growth with 1,2-D and suggested that both D. mccartyi strains carried a single dcpA gene copy per genome. D. mccartyi strain RC and strain KS produced 1.8 × 10(7) ± 0.1 × 10(7) and 1.4 × 10(7) ± 0.5 × 10(7) cells per μmol of propene formed, respectively. The dcpA gene was identified in 1,2-D-to-propene-dechlorinating microcosms established with sediment samples collected from different geographical locations in Europe and North and South America. Clone library analysis revealed two distinct dcpA phylogenetic clusters, both of which were captured by the dcpA gene-targeted qPCR assay, suggesting that the qPCR assay is useful for site assessment and bioremediation monitoring at 1,2-D-contaminated sites.
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24
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Assessment of anaerobic toluene biodegradation activity by bssA transcript/gene ratios. Appl Environ Microbiol 2013; 79:5338-44. [PMID: 23811506 DOI: 10.1128/aem.01031-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Benzylsuccinate synthase (bssA) genes associated with toluene degradation were profiled across a groundwater contaminant plume under nitrate-reducing conditions and were detected in significant numbers throughout the plume. However, differences between groundwater and core sediment samples suggested that microbial transport, rather than local activity, was the underlying cause of the high copy numbers within the downgradient plume. Both gene transcript and reactant concentrations were consistent with this hypothesis. Expression of bssA genes from denitrifying toluene degraders was induced by toluene but only in the presence of nitrate, and transcript abundance dropped rapidly following the removal of either toluene or nitrate. The drop in bssA transcripts following the removal of toluene could be described by an exponential decay function with a half-life on the order of 1 h. Interestingly, bssA transcripts never disappeared completely but were always detected at some level if either inducer was present. Therefore, the detection of transcripts alone may not be sufficient evidence for contaminant degradation. To avoid mistakenly associating basal-level gene expression with actively degrading microbial populations, an integrated approach using the ratio of functional gene transcripts to gene copies is recommended. This approach minimizes the impact of microbial transport on activity assessment and allows reliable assessments of microbial activity to be obtained from water samples.
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25
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Richardson RE. Genomic insights into organohalide respiration. Curr Opin Biotechnol 2013; 24:498-505. [DOI: 10.1016/j.copbio.2013.02.014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/11/2013] [Accepted: 02/12/2013] [Indexed: 12/14/2022]
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26
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Maphosa F, Lieten SH, Dinkla I, Stams AJ, Smidt H, Fennell DE. Ecogenomics of microbial communities in bioremediation of chlorinated contaminated sites. Front Microbiol 2012; 3:351. [PMID: 23060869 PMCID: PMC3462421 DOI: 10.3389/fmicb.2012.00351] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/12/2012] [Indexed: 11/29/2022] Open
Abstract
Organohalide compounds such as chloroethenes, chloroethanes, and polychlorinated benzenes are among the most significant pollutants in the world. These compounds are often found in contamination plumes with other pollutants such as solvents, pesticides, and petroleum derivatives. Microbial bioremediation of contaminated sites, has become commonplace whereby key processes involved in bioremediation include anaerobic degradation and transformation of these organohalides by organohalide respiring bacteria and also via hydrolytic, oxygenic, and reductive mechanisms by aerobic bacteria. Microbial ecogenomics has enabled us to not only study the microbiology involved in these complex processes but also develop tools to better monitor and assess these sites during bioremediation. Microbial ecogenomics have capitalized on recent advances in high-throughput and -output genomics technologies in combination with microbial physiology studies to address these complex bioremediation problems at a system level. Advances in environmental metagenomics, transcriptomics, and proteomics have provided insights into key genes and their regulation in the environment. They have also given us clues into microbial community structures, dynamics, and functions at contaminated sites. These techniques have not only aided us in understanding the lifestyles of common organohalide respirers, for example Dehalococcoides, Dehalobacter, and Desulfitobacterium, but also provided insights into novel and yet uncultured microorganisms found in organohalide respiring consortia. In this paper, we look at how ecogenomic studies have aided us to understand the microbial structures and functions in response to environmental stimuli such as the presence of chlorinated pollutants.
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Affiliation(s)
- Farai Maphosa
- Laboratory of Microbiology, Wageningen UniversityWageningen, Netherlands
| | | | | | - Alfons J. Stams
- Laboratory of Microbiology, Wageningen UniversityWageningen, Netherlands
| | - Hauke Smidt
- Laboratory of Microbiology, Wageningen UniversityWageningen, Netherlands
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27
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Chambon JC, Bjerg PL, Scheutz C, Baelum J, Jakobsen R, Binning PJ. Review of reactive kinetic models describing reductive dechlorination of chlorinated ethenes in soil and groundwater. Biotechnol Bioeng 2012; 110:1-23. [DOI: 10.1002/bit.24714] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 08/13/2012] [Accepted: 08/16/2012] [Indexed: 11/08/2022]
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28
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Ding C, He J. Molecular techniques in the biotechnological fight against halogenated compounds in anoxic environments. Microb Biotechnol 2012; 5:347-67. [PMID: 22070763 PMCID: PMC3821678 DOI: 10.1111/j.1751-7915.2011.00313.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 09/24/2011] [Accepted: 09/28/2011] [Indexed: 11/28/2022] Open
Abstract
Microbial treatment of environmental contamination by anthropogenic halogenated organic compounds has become popular in recent decades, especially in the subsurface environments. Molecular techniques such as polymerase chain reaction-based fingerprinting methods have been extensively used to closely monitor the presence and activities of dehalogenating microbes, which also lead to the discovery of new dehalogenating bacteria and novel functional genes. Nowadays, traditional molecular techniques are being further developed and optimized for higher sensitivity, specificity, and accuracy to better fit the contexts of dehalogenation. On the other hand, newly developed high throughput techniques, such as microarray and next-generation sequencing, provide unsurpassed detection ability, which has enabled large-scale comparative genomic and whole-genome transcriptomic analysis. The aim of this review is to summarize applications of various molecular tools in the field of microbially mediated dehalogenation of various halogenated organic compounds. It is expected that traditional molecular techniques and nucleic-acid-based biomarkers will still be favoured in the foreseeable future because of relative low costs and high flexibility. Collective analyses of metagenomic sequencing data are still in need of information from individual dehalogenating strains and functional reductive dehalogenase genes in order to draw reliable conclusions.
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Affiliation(s)
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576
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29
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Fletcher KE, Costanza J, Pennell KD, Löffler FE. Electron donor availability for microbial reductive processes following thermal treatment. WATER RESEARCH 2011; 45:6625-6636. [PMID: 22048015 DOI: 10.1016/j.watres.2011.09.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 06/16/2011] [Accepted: 09/14/2011] [Indexed: 05/31/2023]
Abstract
Thermal treatment is capable of removing significant free-phase chlorinated solvent mass while potentially enhancing bioremediation effectiveness by establishing temperature gradients in the perimeter of the source zone and by increasing electron donor availability. The objectives of this study were to determine the potential for enhanced reductive dechlorination activity at the intermediate temperatures that establish in the perimeter of the heated source zone, and to evaluate the effect of electron donor competition on the performance of the microbial reductive dechlorination process. Microcosms, constructed with tetrachloroethene- (PCE-) and trichloroethene- (TCE-) impacted soils from the Great Lakes, IL, and Ft. Lewis, WA, sites were incubated at temperatures of 24, 35, 50, 70, and 95 °C for 4 months. Reductive dechlorination did not occur in microcosms incubated at temperatures above 24 °C even though mesophilic PCE-to-cis-1,2-dichloroethene dechlorinators were present in Ft. Lewis soil suggesting electron donor limitations. Five days after cooling the microcosms to 24 °C and bioaugmentation with the methanogenic, PCE-to-ethene-dechlorinating consortium OW, at least 85% of the initial PCE and TCE were dechlorinated, but dechlorination ceased prior to complete conversion to ethene. Subsequent biostimulation with hydrogen gas mitigated the dechlorination stall, and conversion to ethene resumed. The results of this study demonstrated that temperatures >35 °C inhibit reductive dechlorination activity at the Great Lakes and Ft. Lewis sites, and that the majority of reducing equivalents released from the soil matrix during heat treatment are consumed in methanogenesis rather than reductive dechlorination. These observations suggest that bioaugmenting thermal treatment sites with cultures that do not contain methanogens may allow practitioners to realize enhanced dechlorination activity, a potential benefit of coupling thermal treatment with bioremediation.
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Affiliation(s)
- Kelly E Fletcher
- School of Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, USA
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