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Xiao JZ, Nesbø CL, Molenda O, Toth CRA, Edwards EA. Draft genome of an anaerobic nitrate-reducing, benzene-degrading member of the order Thermincolales. Microbiol Resour Announc 2024:e0029524. [PMID: 39189724 DOI: 10.1128/mra.00295-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Accepted: 07/27/2024] [Indexed: 08/28/2024] Open
Abstract
We present a metagenome assembled genome (MAG) of an anaerobic bacterium from a nitrate-reducing, benzene-degrading enrichment culture (NRBC). The draft Thermincolales genome consists of 20 contigs with a total length of 4.09 Mbp and includes putative carboxylase genes likely involved in benzene activation.
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Affiliation(s)
- Johnny Z Xiao
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Camilla L Nesbø
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Olivia Molenda
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Courtney R A Toth
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Elizabeth A Edwards
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
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2
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Hernández-Ospina DA, Osorio-González CS, Miri S, Kaur Brar S. New perspectives on the anaerobic degradation of BTEX: Mechanisms, pathways, and intermediates. CHEMOSPHERE 2024; 361:142490. [PMID: 38821131 DOI: 10.1016/j.chemosphere.2024.142490] [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: 04/05/2024] [Revised: 05/27/2024] [Accepted: 05/29/2024] [Indexed: 06/02/2024]
Abstract
Aromatic hydrocarbons like benzene, toluene, xylene, and ethylbenzene (BTEX) can escape into the environment from oil and gas operations and manufacturing industries posing significant health risks to humans and wildlife. Unlike conventional clean-up methods used, biological approaches such as bioremediation can provide a more energy and labour-efficient and environmentally friendly option for sensitive areas such as nature reserves and cities, protecting biodiversity and public health. BTEX contamination is often concentrated in the subsurface of these locations where oxygen is rapidly depleted, and biodegradation relies on anaerobic processes. Thus, it is critical to understand the anaerobic biodegradation characteristics as it has not been explored to a major extent. This review presents novel insights into the degradation mechanisms under anaerobic conditions and presents a detailed description and interconnection between them. BTEX degradation can follow four activation mechanisms: hydroxylation, carboxylation, methylation, and fumarate addition. Hydroxylation is one of the mechanisms that explains the transformation of benzene into phenol, toluene into benzyl alcohol or p-cresol, and ethylbenzene into 1-phenylethanol. Carboxylation to benzoate is thought to be the primary mechanism of degradation for benzene. Despite being poorly understood, benzene methylation has been also reported. Moreover, fumarate addition is the most widely reported mechanism, present in toluene, ethylbenzene, and xylene degradation. Further research efforts are required to better elucidate new and current alternative catabolic pathways. Likewise, a comprehensive analysis of the enzymes involved as well as the development of advance tools such as omic tools can reveal bottlenecks degradation steps and create more effective on-site strategies to address BTEX pollution.
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Affiliation(s)
- Diego A Hernández-Ospina
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, Ontario, Canada, M3J 1P3
| | - Carlos S Osorio-González
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, Ontario, Canada, M3J 1P3
| | - Saba Miri
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, Ontario, Canada, M3J 1P3
| | - Satinder Kaur Brar
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, Ontario, Canada, M3J 1P3.
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3
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Zehnle H, Otersen C, Benito Merino D, Wegener G. Potential for the anaerobic oxidation of benzene and naphthalene in thermophilic microorganisms from the Guaymas Basin. Front Microbiol 2023; 14:1279865. [PMID: 37840718 PMCID: PMC10570749 DOI: 10.3389/fmicb.2023.1279865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Unsubstituted aromatic hydrocarbons (UAHs) are recalcitrant molecules abundant in crude oil, which is accumulated in subsurface reservoirs and occasionally enters the marine environment through natural seepage or human-caused spillage. The challenging anaerobic degradation of UAHs by microorganisms, in particular under thermophilic conditions, is poorly understood. Here, we established benzene- and naphthalene-degrading cultures under sulfate-reducing conditions at 50°C and 70°C from Guaymas Basin sediments. We investigated the microorganisms in the enrichment cultures and their potential for UAH oxidation through short-read metagenome sequencing and analysis. Dependent on the combination of UAH and temperature, different microorganisms became enriched. A Thermoplasmatota archaeon was abundant in the benzene-degrading culture at 50°C, but catabolic pathways remained elusive, because the archaeon lacked most known genes for benzene degradation. Two novel species of Desulfatiglandales bacteria were strongly enriched in the benzene-degrading culture at 70°C and in the naphthalene-degrading culture at 50°C. Both bacteria encode almost complete pathways for UAH degradation and for downstream degradation. They likely activate benzene via methylation, and naphthalene via direct carboxylation, respectively. The two species constitute the first thermophilic UAH degraders of the Desulfatiglandales. In the naphthalene-degrading culture incubated at 70°C, a Dehalococcoidia bacterium became enriched, which encoded a partial pathway for UAH degradation. Comparison of enriched bacteria with related genomes from environmental samples indicated that pathways for benzene degradation are widely distributed, while thermophily and capacity for naphthalene activation are rare. Our study highlights the capacities of uncultured thermophilic microbes for UAH degradation in petroleum reservoirs and in contaminated environments.
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Affiliation(s)
- Hanna Zehnle
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Carolin Otersen
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - David Benito Merino
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Gunter Wegener
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
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4
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Sun J, Zhang Z, Wang H, Rogers MJ, Guo H, He J. Exploration of the biotransformation of phenanthrene degradation coupled with methanogensis by metabolites and enzyme analyses. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 293:118491. [PMID: 34780757 DOI: 10.1016/j.envpol.2021.118491] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/21/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The ubiquitous environmental contaminants, polycyclic aromatic hydrocarbons (PAHs), can be aerobically biodegraded. Strategies for biodegradation of PAHs are needed for the persisted character of it in anoxic environments. In current study, we obtained a highly enriched anaerobic, PAHs-degrading co-culture DYM1, from petroleum-polluted soil. DYM1 significantly degrades a range of PAHs in 4 days without supplementary terminal electron acceptors. Co-culture DYM1 is consists of two microorganisms (a degrading bacterium Paracoccus sp. strain PheM1 and an aceticlastic methanogen Methanosaeta concilii.) that utilize different carbon sources in a syntrophic metabolic process of phenanthrene. About 93% of phenanthrene (104.5 μM) has been removed under methanogenic conditions after incubation with co-culture DYM1 for 4 d, and produced 33.68 μmol CH4. Carboxylation, which is catalyzed by UbiD-like carboxylase, was proposed as the initial steps of methanogenic phenanthrene-degrading pathway based upon the detection of 2-phenanthroic acid and 4-phenanthrene acid. Reduction and hydration of the benzene rings were followed by the initial reaction. Hydrated phenanthroic acid metabolites were newly detected and characterized under anaerobic conditions. Anaerobic degradation of phenanthrene without terminal electron acceptor addition not only sheds light on a poorly understood and environmentally relevant biological process, but also supply a novel approach to recover the energy of toxic pollutant in forms of methane.
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Affiliation(s)
- Jiao Sun
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Zuotao Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Hui Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China.
| | - Matthew J Rogers
- Department of Civil and Environmental Engineering, National University of Singapore, Engineering Drive, 3117576, Singapore
| | - Haijiao Guo
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Engineering Drive, 3117576, Singapore
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5
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Eziuzor SC, Corrêa FB, Peng S, Schultz J, Kleinsteuber S, da Rocha UN, Adrian L, Vogt C. Structure and functional capacity of a benzene-mineralizing, nitrate-reducing microbial community. J Appl Microbiol 2022; 132:2795-2811. [PMID: 34995421 DOI: 10.1111/jam.15443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/16/2021] [Accepted: 01/04/2022] [Indexed: 11/26/2022]
Abstract
AIMS How benzene is metabolized by microbes under anoxic conditions is not fully understood. Here, we studied the degradation pathways in a benzene-mineralizing, nitrate-reducing enrichment culture. METHODS AND RESULTS Benzene mineralization was dependent on the presence of nitrate and correlated to the enrichment of a Peptococcaceae phylotype only distantly related to known anaerobic benzene degraders of this family. Its relative abundance decreased after benzene mineralization had terminated, while other abundant taxa-Ignavibacteriaceae, Rhodanobacteraceae and Brocadiaceae-slightly increased. Generally, the microbial community remained diverse despite the amendment of benzene as single organic carbon source, suggesting complex trophic interactions between different functional groups. A subunit of the putative anaerobic benzene carboxylase previously detected in Peptococcaceae was identified by metaproteomic analysis suggesting that benzene was activated by carboxylation. Detection of proteins involved in anaerobic ammonium oxidation (anammox) indicates that benzene mineralization was accompanied by anammox, facilitated by nitrite accumulation and the presence of ammonium in the growth medium. CONCLUSIONS The results suggest that benzene was activated by carboxylation and further assimilated by a novel Peptococcaceae phylotype. SIGNIFICANCE AND IMPACT OF THE STUDY The results confirm the hypothesis that Peptococcaceae are important anaerobic benzene degraders.
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Affiliation(s)
- Samuel C Eziuzor
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Felipe B Corrêa
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Shuchan Peng
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany.,Department of Environmental Science, Chongqing University, Chongqing, China
| | - Júnia Schultz
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany.,Departamento de Microbiologia Geral, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.,Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Ulisses N da Rocha
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Lorenz Adrian
- Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Geobiotechnology, Technische Universität Berlin, Berlin, Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
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6
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Zamanpour MK, Kaliappan RS, Rockne KJ. Gas ebullition from petroleum hydrocarbons in aquatic sediments: A review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 271:110997. [PMID: 32778285 DOI: 10.1016/j.jenvman.2020.110997] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 05/19/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
Gas ebullition in sediment results from biogenic gas production by mixtures of bacteria and archaea. It often occurs in organic-rich sediments that have been impacted by petroleum hydrocarbon (PHC) and other anthropogenic pollution. Ebullition occurs under a relatively narrow set of biological, chemical, and sediment geomechanical conditions. This process occurs in three phases: I) biogenic production of primarily methane and dissolved phase transport of the gases in the pore water to a bubble nucleation site, II) bubble growth and sediment fracture, and III) bubble rise to the surface. The rate of biogenic gas production in phase I and the resistance of the sediment to gas fracture in phase II play the most significant roles in ebullition kinetics. What is less understood is the role that substrate structure plays in the rate of methanogenesis that drives gas ebullition. It is well established that methanogens have a very restricted set of compounds that can serve as substrates, so any complex organic molecule must first be broken down to fermentable compounds. Given that most ebullition-active sediments are completely anaerobic, the well-known difficulty in degrading PHCs under anaerobic conditions suggests potential limitations on PHC-derived gas ebullition. To date, there are no studies that conclusively demonstrate that weathered PHCs can alone drive gas ebullition. This review consists of an overview of the factors affecting gas ebullition and the biochemistry of anaerobic PHC biodegradation and methanogenesis in sediment systems. We next compile results from the scholarly literature on PHCs serving as a source of methanogenesis. We combine these results to assess the potential for PHC-driven gas ebullition using energetics, kinetics, and sediment geomechanics analyses. The results suggest that short chain <C10 alkanes are the only PHC class that alone may have the potential to drive ebullition, and that PHC-derived methanogenesis likely plays a minor part in driving gas ebullition in contaminated sediments compared to natural organic matter.
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Affiliation(s)
| | - Raja Shankar Kaliappan
- Department of Civil and Materials Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Karl John Rockne
- Department of Civil and Materials Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.
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7
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An LC-MS/MS Method for a Comprehensive Determination of Metabolites of BTEX Anaerobic Degradation in Bacterial Cultures and Groundwater. WATER 2020. [DOI: 10.3390/w12071869] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BTEX (benzene, toluene, ethylbenzene, and the different xylene isomers), known for carcinogenic and neurotoxic effects, are common environmental contaminants. The first step for the development of the bioremediation technologies is the detection of intense microbial degradation in contaminated waters in the quest for the most active bacterial strains. This requires the multispecies analysis for BTEX metabolites which are considered as markers of microbial degradation. A direct (50 µL injection) HPLC–electrospray MS/MS analytical method was developed for the simultaneous analysis of 11 BTEX metabolites (o-, m-, p-toluic, salicylic, benzoate, benzyl, and phenyl succinic acids, 2-(1-phenylethyl)-, 2-(2-methylbenzyl), and 2-(3-methylbenzyl)-, 2-(4-methyl benzyl)-succinic acids) in bacterial cultures and ground waters down to 0.1 ng/mL. The optimization of the chromatographic conditions allowed for the resolution of position isomers of toluic and methylbenzyl-succinic acids. The stability of the analytes during sample storage tested in different conditions showed the instability of some of them when stored at room temperature. The feasibility of the method was demonstrated by the detection of all the investigated metabolites in a water sample of a deep aquifer hosting natural gas storage. A model laboratory study emphasized the importance of 2-(2-methylbenzyl)-succinic acid as a marker of anaerobic microbial degradation.
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8
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Hidalgo KJ, Teramoto EH, Soriano AU, Valoni E, Baessa MP, Richnow HH, Vogt C, Chang HK, Oliveira VM. Taxonomic and functional diversity of the microbiome in a jet fuel contaminated site as revealed by combined application of in situ microcosms with metagenomic analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 708:135152. [PMID: 31812384 DOI: 10.1016/j.scitotenv.2019.135152] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
Natural attenuation represents all processes that govern contaminant mass removal, which mainly occurs via microbial degradation in the environment. Although this process is intrinsic its rate and efficiency depend on multiple factors. This study aimed to characterize the microbial taxonomic and functional diversity in different aquifer sediments collected in the saturated zone and in situ microcosms (BACTRAP®s) amended with hydrocarbons (13C-labeled and non-labeled benzene, toluene and naphthalene) using 16S rRNA gene and "shotgun" Illumina high throughput sequencing at a jet-fuel contaminated site. The BACTRAP®s were installed to assess hydrocarbon metabolism by native bacteria. Results indicated that Proteobacteria, Actinobacteria and Firmicutes were the most dominant phyla (~98%) in the aquifer sediment samples. Meanwhile, in the benzene- and toluene-amended BACTRAP®s the phyla Firmicutes and Proteobacteria accounted for about 90% of total community. In the naphthalene-amended BACTRAP®, members of the SR-FBR-L83 family (Order Ignavibacteriales) accounted for almost 80% of bacterial community. Functional annotation of metagenomes showed that only the sediment sample located at the source zone border and with the lowest BTEX concentration, has metabolic potential to degrade hydrocarbons aerobically. On the other hand, in situ BACTRAP®s allowed enrichment of hydrocarbon-degrading bacteria. Metagenomic data suggest that fumarate addition is the main mechanism for hydrocarbon activation of toluene. Also, indications for methylation, hydroxylation and carboxylation as activation mechanisms for benzene anaerobic conversion were found. After 120 days of exposure in the contaminated groundwater, the isotopic analysis of fatty acids extracted from BACTRAP®s demonstrated the assimilation of isotopic labeled compounds in the cells of microbes expressed by strong isotopic enrichment. We propose that the microbiota in this jet-fuel contaminated site has metabolic potential to degrade benzene and toluene by a syntrophic process, between members of the families Geobacteraceae and Peptococcaceae (genus Pelotomaculum), coupled to nitrate, iron and/or sulfate reduction.
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Affiliation(s)
- K J Hidalgo
- Graduate Program in Genetics and Molecular Biology, Institute of Biology, University of Campinas (UNICAMP), Rua Monteiro Lobato 255, Cidade Universitária, Campinas, SP. ZIP 13083-862, Brazil.
| | - E H Teramoto
- Laboratory of Basin Studies (LEBAC), São Paulo State University (UNESP), Rio Claro, Av. 24A, 1515 ZIP 13506-900, Brazil
| | - A U Soriano
- PETROBRAS/ R&D Center (CENPES), Av. Horácio Macedo, 950. ZIP 21941-915 Ilha do Fundão, Rio de Janeiro, Brazil
| | - E Valoni
- PETROBRAS/ R&D Center (CENPES), Av. Horácio Macedo, 950. ZIP 21941-915 Ilha do Fundão, Rio de Janeiro, Brazil
| | - M P Baessa
- PETROBRAS/ R&D Center (CENPES), Av. Horácio Macedo, 950. ZIP 21941-915 Ilha do Fundão, Rio de Janeiro, Brazil
| | - H H Richnow
- Department Isotope Biogeochemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstrasse 15 04318 Leipzig, Germany
| | - C Vogt
- Department Isotope Biogeochemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstrasse 15 04318 Leipzig, Germany
| | - H K Chang
- Laboratory of Basin Studies (LEBAC), São Paulo State University (UNESP), Rio Claro, Av. 24A, 1515 ZIP 13506-900, Brazil
| | - V M Oliveira
- Microbial Resources Division, Research Center for Chemistry, Biology and Agriculture (CPQBA), University of Campinas - UNICAMP, Paulínia, Brazil, Av. Alexandre Cazellato, 999, ZIP 13148-218, Brazil
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9
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Dhar K, Subashchandrabose SR, Venkateswarlu K, Krishnan K, Megharaj M. Anaerobic Microbial Degradation of Polycyclic Aromatic Hydrocarbons: A Comprehensive Review. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2020; 251:25-108. [PMID: 31011832 DOI: 10.1007/398_2019_29] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a class of hazardous organic contaminants that are widely distributed in nature, and many of them are potentially toxic to humans and other living organisms. Biodegradation is the major route of detoxification and removal of PAHs from the environment. Aerobic biodegradation of PAHs has been the subject of extensive research; however, reports on anaerobic biodegradation of PAHs are so far limited. Microbial degradation of PAHs under anaerobic conditions is difficult because of the slow growth rate of anaerobes and low energy yield in the metabolic processes. Despite the limitations, some anaerobic bacteria degrade PAHs under nitrate-reducing, sulfate-reducing, iron-reducing, and methanogenic conditions. Anaerobic biodegradation, though relatively slow, is a significant process of natural attenuation of PAHs from the impacted anoxic environments such as sediments, subsurface soils, and aquifers. This review is intended to provide comprehensive details on microbial degradation of PAHs under various reducing conditions, to describe the degradation mechanisms, and to identify the areas that should receive due attention in further investigations.
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Affiliation(s)
- Kartik Dhar
- Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
- Department of Microbiology, University of Chittagong, Chittagong, Bangladesh
| | - Suresh R Subashchandrabose
- Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
| | - Kadiyala Venkateswarlu
- Formerly Department of Microbiology, Sri Krishnadevaraya University, Anantapuramu, India
| | - Kannan Krishnan
- Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia
| | - Mallavarapu Megharaj
- Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW, Australia.
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10
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Truskewycz A, Gundry TD, Khudur LS, Kolobaric A, Taha M, Aburto-Medina A, Ball AS, Shahsavari E. Petroleum Hydrocarbon Contamination in Terrestrial Ecosystems-Fate and Microbial Responses. Molecules 2019; 24:molecules24183400. [PMID: 31546774 PMCID: PMC6767264 DOI: 10.3390/molecules24183400] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 09/06/2019] [Accepted: 09/11/2019] [Indexed: 11/18/2022] Open
Abstract
Petroleum hydrocarbons represent the most frequent environmental contaminant. The introduction of petroleum hydrocarbons into a pristine environment immediately changes the nature of that environment, resulting in reduced ecosystem functionality. Natural attenuation represents the single, most important biological process which removes petroleum hydrocarbons from the environment. It is a process where microorganisms present at the site degrade the organic contaminants without the input of external bioremediation enhancers (i.e., electron donors, electron acceptors, other microorganisms or nutrients). So successful is this natural attenuation process that in environmental biotechnology, bioremediation has developed steadily over the past 50 years based on this natural biodegradation process. Bioremediation is recognized as the most environmentally friendly remediation approach for the removal of petroleum hydrocarbons from an environment as it does not require intensive chemical, mechanical, and costly interventions. However, it is under-utilized as a commercial remediation strategy due to incomplete hydrocarbon catabolism and lengthy remediation times when compared with rival technologies. This review aims to describe the fate of petroleum hydrocarbons in the environment and discuss their interactions with abiotic and biotic components of the environment under both aerobic and anaerobic conditions. Furthermore, the mechanisms for dealing with petroleum hydrocarbon contamination in the environment will be examined. When petroleum hydrocarbons contaminate land, they start to interact with its surrounding, including physical (dispersion), physiochemical (evaporation, dissolution, sorption), chemical (photo-oxidation, auto-oxidation), and biological (plant and microbial catabolism of hydrocarbons) interactions. As microorganism (including bacteria and fungi) play an important role in the degradation of petroleum hydrocarbons, investigations into the microbial communities within contaminated soils is essential for any bioremediation project. This review highlights the fate of petroleum hydrocarbons in tertial environments, as well as the contributions of different microbial consortia for optimum petroleum hydrocarbon bioremediation potential. The impact of high-throughput metagenomic sequencing in determining the underlying degradation mechanisms is also discussed. This knowledge will aid the development of more efficient, cost-effective commercial bioremediation technologies.
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Affiliation(s)
- Adam Truskewycz
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Taylor D Gundry
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Leadin S Khudur
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Adam Kolobaric
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Mohamed Taha
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
- Department of Biochemistry, Faculty of Agriculture, Benha University, Moshtohor, Toukh, Qaliuobia 13736, Egypt.
| | - Arturo Aburto-Medina
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Andrew S Ball
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
| | - Esmaeil Shahsavari
- Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, VIC 3083, Australia.
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11
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Gao Y, Wang G, Zhou A, Yue X, Duan Y, Kong X, Zhang X. Effect of nitrate on indole degradation characteristics and methanogenesis under mixed denitrification and methanogenesis culture. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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12
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Sekar R, DiChristina TJ. Degradation of the recalcitrant oil spill components anthracene and pyrene by a microbially driven Fenton reaction. FEMS Microbiol Lett 2018; 364:4222791. [PMID: 29029043 DOI: 10.1093/femsle/fnx203] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 09/23/2017] [Indexed: 12/30/2022] Open
Abstract
Oil spill components include a range of toxic saturated, aromatic and polar hydrocarbons, including pyrene and anthracene. Such contaminants harm natural ecosystems, adversely affect human health and negatively impact tourism and the fishing industries. Current physical, chemical and biological remediation technologies are often unable to completely remove recalcitrant oil spill components, which accumulate at levels greater than regulatory limits set by the Environmental Protection Agency. In the present study, a microbially driven Fenton reaction, previously shown to produce hydroxyl (HO • ) radicals that degrade chlorinated solvents and associated solvent stabilizers, was also found to degrade source zone concentrations of the oil spill components, pyrene (10 μM) and anthracene (1 μM), at initial rates of 0.82 and 0.20 μM h -1 , respectively. The pyrene- and anthracene-degrading Fenton reaction was driven by the metal-reducing facultative anaerobe Shewanella oneidensis exposed to alternating aerobic and anaerobic conditions in the presence of Fe(III). Similar to the chlorinated solvent degradation system, the pyrene and anthracene degradation systems required neither the continual supply of exogenous H 2 O 2 nor UV-induced Fe(III) reduction to regenerate Fe(II). The microbially driven Fenton reaction provides the foundation for the development of alternate ex situ and in situ oil and gas spill remediation technologies.
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Affiliation(s)
- Ramanan Sekar
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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13
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Keller AH, Kleinsteuber S, Vogt C. Anaerobic Benzene Mineralization by Nitrate-Reducing and Sulfate-Reducing Microbial Consortia Enriched From the Same Site: Comparison of Community Composition and Degradation Characteristics. MICROBIAL ECOLOGY 2018; 75:941-953. [PMID: 29124312 DOI: 10.1007/s00248-017-1100-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 10/26/2017] [Indexed: 05/22/2023]
Abstract
Benzene mineralization under nitrate-reducing conditions was successfully established in an on-site reactor continuously fed with nitrate and sulfidic, benzene-containing groundwater extracted from a contaminated aquifer. Filling material from the reactor columns was used to set up anoxic enrichment cultures in mineral medium with benzene as electron donor and sole organic carbon source and nitrate as electron acceptor. Benzene degradation characteristics and community composition under nitrate-reducing conditions were monitored and compared to those of a well-investigated benzene-mineralizing consortium enriched from the same column system under sulfate-reducing conditions. The nitrate-reducing cultures degraded benzene at a rate of 10.1 ± 1.7 μM d-1, accompanied by simultaneous reduction of nitrate to nitrite. The previously studied sulfate-reducing culture degraded benzene at similar rates. Carbon and hydrogen stable isotope enrichment factors determined for nitrate-dependent benzene degradation differed significantly from those of the sulfate-reducing culture (ΛH/C nitrate = 12 ± 3 compared to ΛH/C sulfate = 28 ± 3), indicating different benzene activation mechanisms under the two conditions. The nitrate-reducing community was mainly composed of Betaproteobacteria, Ignavibacteria, and Anaerolineae. Azoarcus and a phylotype related to clone Dok59 (Rhodocyclaceae) were the dominant genera, indicating an involvement in nitrate-dependent benzene degradation. The primary benzene degrader of the sulfate-reducing consortium, a phylotype belonging to the Peptococcaceae, was absent in the nitrate-reducing consortium.
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Affiliation(s)
- Andreas H Keller
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, 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.
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A benzene-degrading nitrate-reducing microbial consortium displays aerobic and anaerobic benzene degradation pathways. Sci Rep 2018. [PMID: 29540736 PMCID: PMC5852087 DOI: 10.1038/s41598-018-22617-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this study, we report transcription of genes involved in aerobic and anaerobic benzene degradation pathways in a benzene-degrading denitrifying continuous culture. Transcripts associated with the family Peptococcaceae dominated all samples (21-36% relative abundance) indicating their key role in the community. We found a highly transcribed gene cluster encoding a presumed anaerobic benzene carboxylase (AbcA and AbcD) and a benzoate-coenzyme A ligase (BzlA). Predicted gene products showed >96% amino acid identity and similar gene order to the corresponding benzene degradation gene cluster described previously, providing further evidence for anaerobic benzene activation via carboxylation. For subsequent benzoyl-CoA dearomatization, bam-like genes analogous to the ones found in other strict anaerobes were transcribed, whereas gene transcripts involved in downstream benzoyl-CoA degradation were mostly analogous to the ones described in facultative anaerobes. The concurrent transcription of genes encoding enzymes involved in oxygenase-mediated aerobic benzene degradation suggested oxygen presence in the culture, possibly formed via a recently identified nitric oxide dismutase (Nod). Although we were unable to detect transcription of Nod-encoding genes, addition of nitrite and formate to the continuous culture showed indication for oxygen production. Such an oxygen production would enable aerobic microbes to thrive in oxygen-depleted and nitrate-containing subsurface environments contaminated with hydrocarbons.
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15
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Ghattas AK, Fischer F, Wick A, Ternes TA. Anaerobic biodegradation of (emerging) organic contaminants in the aquatic environment. WATER RESEARCH 2017; 116:268-295. [PMID: 28347952 DOI: 10.1016/j.watres.2017.02.001] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/31/2017] [Accepted: 02/01/2017] [Indexed: 05/22/2023]
Abstract
Although strictly anaerobic conditions prevail in several environmental compartments, up to now, biodegradation studies with emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products, have mainly focused on aerobic conditions. One of the reasons probably is the assumption that the aerobic degradation is more energetically favorable than degradation under strictly anaerobic conditions. Certain aerobically recalcitrant contaminants, however, are biodegraded under strictly anaerobic conditions and little is known about the organisms and enzymatic processes involved in their degradation. This review provides a comprehensive survey of characteristic anaerobic biotransformation reactions for a variety of well-studied, structurally rather simple contaminants (SMOCs) bearing one or a few different functional groups/structural moieties. Furthermore it summarizes anaerobic degradation studies of more complex contaminants with several functional groups (CMCs), in soil, sediment and wastewater treatment. While strictly anaerobic conditions are able to promote the transformation of several aerobically persistent contaminants, the variety of observed reactions is limited, with reductive dehalogenations and the cleavage of ether bonds being the most prevalent. Thus, it becomes clear that the transferability of degradation mechanisms deduced from culture studies of SMOCs to predict the degradation of CMCs, such as EOCs, in environmental matrices is hampered due the more complex chemical structure bearing different functional groups, different environmental conditions (e.g. matrix, redox, pH), the microbial community (e.g. adaptation, competition) and the low concentrations typical for EOCs.
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Affiliation(s)
- Ann-Kathrin Ghattas
- Federal Institute of Hydrology (BfG), D-56068 Koblenz, Am Mainzer Tor 1, Germany
| | - Ferdinand Fischer
- Federal Institute of Hydrology (BfG), D-56068 Koblenz, Am Mainzer Tor 1, Germany
| | - Arne Wick
- Federal Institute of Hydrology (BfG), D-56068 Koblenz, Am Mainzer Tor 1, Germany
| | - Thomas A Ternes
- Federal Institute of Hydrology (BfG), D-56068 Koblenz, Am Mainzer Tor 1, Germany.
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van der Waals MJ, Atashgahi S, da Rocha UN, van der Zaan BM, Smidt H, Gerritse J. Benzene degradation in a denitrifying biofilm reactor: activity and microbial community composition. Appl Microbiol Biotechnol 2017; 101:5175-5188. [PMID: 28321487 PMCID: PMC5486827 DOI: 10.1007/s00253-017-8214-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/27/2017] [Accepted: 03/04/2017] [Indexed: 11/26/2022]
Abstract
Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more than 14 years on benzene with nitrate as electron acceptor. We determined steady state degradation rates, microbial community composition dynamics in the biofilm, and the initial anaerobic benzene degradation reactions. Benzene was degraded at a rate of 0.15 μmol/mg protein/day and a first-order rate constant of 3.04/day which was fourfold higher than rates reported previously. Bacteria belonging to the Peptococcaceae were found to play an important role in this anaerobic benzene-degrading biofilm culture, but also members of the Anaerolineaceae were predicted to be involved in benzene degradation or benzene metabolite degradation based on Illumina MiSeq analysis of 16S ribosomal RNA genes. Biomass retention in the reactor using a filtration finger resulted in reduction of benzene degradation capacity. Detection of the benzene carboxylase encoding gene, abcA, and benzoic acid in the culture vessel indicated that benzene degradation proceeds through an initial carboxylation step.
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Affiliation(s)
- Marcelle J van der Waals
- Deltares, Subsurface and Groundwater Systems, Princetonlaan 6, 3584 CB, Utrecht, The Netherlands.
- Wageningen University & Research, Laboratory of Microbiology, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Siavash Atashgahi
- Wageningen University & Research, Laboratory of Microbiology, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Ulisses Nunes da Rocha
- VU University of Amsterdam, Department of Molecular Cell Physiology, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Bas M van der Zaan
- Deltares, Subsurface and Groundwater Systems, Princetonlaan 6, 3584 CB, Utrecht, The Netherlands
| | - Hauke Smidt
- Wageningen University & Research, Laboratory of Microbiology, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Jan Gerritse
- Deltares, Subsurface and Groundwater Systems, Princetonlaan 6, 3584 CB, Utrecht, The Netherlands
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17
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Denitrification synergized with ANAMMOX for the anaerobic degradation of benzene: performance and microbial community structure. Appl Microbiol Biotechnol 2017; 101:4315-4325. [DOI: 10.1007/s00253-017-8166-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/25/2017] [Accepted: 02/05/2017] [Indexed: 12/21/2022]
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18
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Starke R, Keller A, Jehmlich N, Vogt C, Richnow HH, Kleinsteuber S, von Bergen M, Seifert J. Pulsed (13)C2-Acetate Protein-SIP Unveils Epsilonproteobacteria as Dominant Acetate Utilizers in a Sulfate-Reducing Microbial Community Mineralizing Benzene. MICROBIAL ECOLOGY 2016; 71:901-11. [PMID: 26846217 DOI: 10.1007/s00248-016-0731-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/18/2016] [Indexed: 05/23/2023]
Abstract
In a benzene-degrading and sulfate-reducing syntrophic consortium, a clostridium affiliated to the genus Pelotomaculum was previously described to ferment benzene while various sulfate-reducing Deltaproteobacteria and a member of the Epsilonproteobacteria were supposed to utilize acetate and hydrogen as key metabolites derived from benzene fermentation. However, the acetate utilization network within this community was not yet unveiled. In this study, we performed a pulsed (13)C2-acetate protein stable isotope probing (protein-SIP) approach continuously spiking low amounts of acetate (10 μM per day) in addition to the ongoing mineralization of unlabeled benzene. Metaproteomics revealed high abundances of Clostridiales followed by Syntrophobacterales, Desulfobacterales, Desulfuromonadales, Desulfovibrionales, Archaeoglobales, and Campylobacterales. Pulsed acetate protein-SIP results indicated that members of the Campylobacterales, the Syntrophobacterales, the Archaeoglobales, the Clostridiales, and the Desulfobacterales were linked to acetate utilization in descending abundance. The Campylobacterales revealed the fastest and highest (13)C incorporation. Previous experiments suggested that the activity of the Campylobacterales was not essential for anaerobic benzene degradation in the investigated community. However, these organisms were consistently detected in various hydrocarbon-degrading and sulfate-reducing consortia enriched from the same aquifer. Here, we demonstrate that this member of the Campylobacterales is the dominant acetate utilizer in the benzene-degrading microbial consortium.
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Affiliation(s)
- Robert Starke
- Institute for Animal Science, University of Hohenheim, Emil-Wolff-Str. 6-10, 70599, Stuttgart, Germany
- Department of Proteomics, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Andreas Keller
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Nico Jehmlich
- Department of Proteomics, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Hans H Richnow
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Martin von Bergen
- Department of Proteomics, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
- Department of Metabolomics, Helmholtz-Centre for Environmental Research (UFZ), Permoserstr. 15, 04318, Leipzig, Germany
| | - Jana Seifert
- Institute for Animal Science, University of Hohenheim, Emil-Wolff-Str. 6-10, 70599, Stuttgart, Germany.
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Meckenstock RU, Boll M, Mouttaki H, Koelschbach JS, Cunha Tarouco P, Weyrauch P, Dong X, Himmelberg AM. Anaerobic Degradation of Benzene and Polycyclic Aromatic Hydrocarbons. J Mol Microbiol Biotechnol 2016; 26:92-118. [DOI: 10.1159/000441358] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aromatic hydrocarbons such as benzene and polycyclic aromatic hydrocarbons (PAHs) are very slowly degraded without molecular oxygen. Here, we review the recent advances in the elucidation of the first known degradation pathways of these environmental hazards. Anaerobic degradation of benzene and PAHs has been successfully documented in the environment by metabolite analysis, compound-specific isotope analysis and microcosm studies. Subsequently, also enrichments and pure cultures were obtained that anaerobically degrade benzene, naphthalene or methylnaphthalene, and even phenanthrene, the largest PAH currently known to be degradable under anoxic conditions. Although such cultures grow very slowly, with doubling times of around 2 weeks, and produce only very little biomass in batch cultures, successful proteogenomic, transcriptomic and biochemical studies revealed novel degradation pathways with exciting biochemical reactions such as for example the carboxylation of naphthalene or the ATP-independent reduction of naphthoyl-coenzyme A. The elucidation of the first anaerobic degradation pathways of naphthalene and methylnaphthalene at the genetic and biochemical level now opens the door to studying the anaerobic metabolism and ecology of anaerobic PAH degraders. This will contribute to assessing the fate of one of the most important contaminant classes in anoxic sediments and aquifers.
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20
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Ponsin V, Mouloubou OR, Prudent P, Höhener P. Does phosphate enhance the natural attenuation of crude oil in groundwater under defined redox conditions? JOURNAL OF CONTAMINANT HYDROLOGY 2014; 169:4-18. [PMID: 24795042 DOI: 10.1016/j.jconhyd.2014.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/11/2014] [Accepted: 04/09/2014] [Indexed: 06/03/2023]
Abstract
After a crude oil spill caused by a broken pipeline in 2009 to a gravel aquifer in southern France, degradation processes under various redox conditions progressively established, but at rates that predict a long life-time of the source under natural attenuation after partial source removal. In this study, we aimed at identifying the rate-limiting factors for each redox condition, with special emphasis on phosphate as limiting nutrient. The study was conducted in laboratory microcosms assembled with material collected on site: sediments, water from monitoring wells, oil and microbial sludge. Redox conditions were promoted by adding electron acceptors (either oxygen, nitrate, limonite (FeO(OH)), cryptomelane (K(Mn(4+),Mn(2+))8O16), or sulfate). For each condition, the role of phosphate was studied by repeated additions for up to 290days. The results showed a very strong stimulation of aerobic and denitrifying rates of oil degradation by phosphate, provided that oxygen and nitrate were repeatedly supplied. Phosphate caused also a marked stimulation of methanogenic degradation, and a relatively small stimulation of metal reduction. These anaerobic processes started only after marked lag phases, and phosphate shortened the lag phase for methanogenic degradation. Degradation of aromatic and aliphatic hydrocarbons with less than 8 carbons, including benzene, was confirmed even under unstimulated conditions. It is concluded that degradation rates at the site are limited by both, availability of electron acceptors and availability of phosphate needed for promoting microbial growth.
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Affiliation(s)
- Violaine Ponsin
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France; French Environment and Energy Management Agency, 20 avenue de Grésillé-BP 90406 Angers Cedex 01, France
| | | | - Pascale Prudent
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France
| | - Patrick Höhener
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France.
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21
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Porter AW, Young LY. Benzoyl-CoA, a universal biomarker for anaerobic degradation of aromatic compounds. ADVANCES IN APPLIED MICROBIOLOGY 2014; 88:167-203. [PMID: 24767428 DOI: 10.1016/b978-0-12-800260-5.00005-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Aromatic compounds are a major component of the global carbon pool and include a diverse range of compounds such as humic acid, lignin, amino acids, and industrial contaminants. Due to the prevalence of aromatic compounds in the environment, aerobic and anaerobic microorganisms have evolved mechanisms by which to metabolize that available carbon. Less well understood are the anaerobic pathways. We now know that anaerobic metabolism of a variety of monoaromatic compounds can be initiated in a number of different ways, and a key metabolite for these pathways is benzoyl-CoA. Chemicals can have different upstream anaerobic degradation pathways yet can still be assessed by targeting the downstream benzoyl-CoA pathway. In this pathway, we propose that the ring opening hydrolase, encoded by the bamA gene, is especially useful because, in contrast to the benzoyl-CoA reductase, it is detected under a number of respiratory settings, including denitrifying, iron-reducing, sulfate-reducing, and fermentative conditions, and has a wide distribution in the environment. This review examines the bamA gene in enrichment cultures and environmental DNA extracts to consider whether it can be used as a biomarker for anaerobic aromatic degradation. Given the number of potential upstream inputs from natural and man-made monoaromatic compounds, the benzoyl-CoA pathway and the bamA gene in particular may play an important role in the global carbon cycle that has thus far been overlooked.
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Affiliation(s)
- Abigail W Porter
- Department of Environmental Science, School of Biological and Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA.
| | - Lily Y Young
- Department of Environmental Science, School of Biological and Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA
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22
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23
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Rethinking biological activation of methane and conversion to liquid fuels. Nat Chem Biol 2014; 10:331-9. [PMID: 24743257 DOI: 10.1038/nchembio.1509] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 03/25/2014] [Indexed: 11/08/2022]
Abstract
If methane, the main component of natural gas, can be efficiently converted to liquid fuels, world reserves of methane could satisfy the demand for transportation fuels in addition to use in other sectors. However, the direct activation of strong C-H bonds in methane and conversion to desired products remains a difficult technological challenge. This perspective reveals an opportunity to rethink the logic of biological methane activation and conversion to liquid fuels. We formulate a vision for a new foundation for methane bioconversion and suggest paths to develop technologies for the production of liquid transportation fuels from methane at high carbon yield and high energy efficiency and with low CO2 emissions. These technologies could support natural gas bioconversion facilities with a low capital cost and at small scales, which in turn could monetize the use of natural gas resources that are frequently flared, vented or emitted.
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Zhang T, Tremblay PL, Chaurasia AK, Smith JA, Bain TS, Lovley DR. Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens. Front Microbiol 2014; 5:245. [PMID: 24904558 PMCID: PMC4033198 DOI: 10.3389/fmicb.2014.00245] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/05/2014] [Indexed: 11/13/2022] Open
Abstract
Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter metallireducens can anaerobically oxidize benzene to carbon dioxide with Fe(III) as the sole electron acceptor and that phenol is an intermediate in benzene oxidation. In an attempt to identify enzymes that might be involved in the conversion of benzene to phenol, whole-genome gene transcript abundance was compared in cells metabolizing benzene and cells metabolizing phenol. Eleven genes had significantly higher transcript abundance in benzene-metabolizing cells. Five of these genes had annotations suggesting that they did not encode proteins that could be involved in benzene metabolism and were not further studied. Strains were constructed in which one of the remaining six genes was deleted. The strain in which the monocistronic gene Gmet 0232 was deleted metabolized phenol, but not benzene. Transcript abundance of the adjacent monocistronic gene, Gmet 0231, predicted to encode a zinc-containing oxidoreductase, was elevated in cells metabolizing benzene, although not at a statistically significant level. However, deleting Gmet 0231 also yielded a strain that could metabolize phenol, but not benzene. Although homologs of Gmet 0231 and Gmet 0232 are found in microorganisms not known to anaerobically metabolize benzene, the adjacent localization of these genes is unique to G. metallireducens. The discovery of genes that are specifically required for the metabolism of benzene, but not phenol in G. metallireducens is an important step in potentially identifying the mechanisms for anaerobic benzene activation.
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Affiliation(s)
- Tian Zhang
- Department of Microbiology, University of Massachusetts Amherst, MA, USA ; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark Hørsholm, Denmark
| | - Pier-Luc Tremblay
- Department of Microbiology, University of Massachusetts Amherst, MA, USA ; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark Hørsholm, Denmark
| | | | - Jessica A Smith
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | - Timothy S Bain
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
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Metatranscriptome of an anaerobic benzene-degrading, nitrate-reducing enrichment culture reveals involvement of carboxylation in benzene ring activation. Appl Environ Microbiol 2014; 80:4095-107. [PMID: 24795366 DOI: 10.1128/aem.00717-14] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzymes involved in the initial steps of anaerobic benzene catabolism are not known. To try to elucidate this critical step, a metatranscriptomic analysis was conducted to compare the genes transcribed during the metabolism of benzene and benzoate by an anaerobic benzene-degrading, nitrate-reducing enrichment culture. RNA was extracted from the mixed culture and sequenced without prior mRNA enrichment, allowing simultaneous examination of the active community composition and the differential gene expression between the two treatments. Ribosomal and mRNA sequences attributed to a member of the family Peptococcaceae from the order Clostridiales were essentially only detected in the benzene-amended culture samples, implicating this group in the initial catabolism of benzene. Genes similar to each of two subunits of a proposed benzene-carboxylating enzyme were transcribed when the culture was amended with benzene. Anaerobic benzoate degradation genes from strict anaerobes were transcribed only when the culture was amended with benzene. Genes for other benzoate catabolic enzymes and for nitrate respiration were transcribed in both samples, with those attributed to an Azoarcus species being most abundant. These findings indicate that the mineralization of benzene starts with its activation by a strict anaerobe belonging to the Peptococcaceae, involving a carboxylation step to form benzoate. These data confirm the previously hypothesized syntrophic association between a benzene-degrading Peptococcaceae strain and a benzoate-degrading denitrifying Azoarcus strain for the complete catabolism of benzene with nitrate as the terminal electron acceptor.
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26
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Porter AW, Young LY. The bamA gene for anaerobic ring fission is widely distributed in the environment. Front Microbiol 2013; 4:302. [PMID: 24133487 PMCID: PMC3794298 DOI: 10.3389/fmicb.2013.00302] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 09/19/2013] [Indexed: 11/13/2022] Open
Abstract
Benzoyl-CoA is the signature central metabolite associated with the anaerobic metabolism of a diverse range of compounds such as humic acid, lignin, amino acids, and industrial chemicals. Aromatic chemicals with different upstream degradation pathways all funnel into the downstream benzoyl-CoA pathway. Different genes encoding enzymes of the benzoyl-CoA pathway could be used as biomarkers for the anaerobic benzoyl-CoA pathway, however, the ring opening hydrolase, encoded by the bamA gene, is ideal because it is detected under a range of respiratory conditions, including under denitrifying, iron-reducing, sulfate-reducing, and fermentative conditions. This work evaluated DNA samples from six diverse environments for the presence of the bamA gene, and had positive results for every sample. Individual bamA gene clones from these sites were compared to published genome sequences. The clone sequences were distributed amongst the genome sequences, although there were clone sequences from two of the analyzed sites that formed a unique clade. Clone sequences were then grouped by site and analyzed with a functional operational taxonomic unit based clustering program to compare the bamA gene diversity of these sites to that of several locations reported in the literature. The results showed that the sequence diversity of the sites separated into two clusters, but there was no clear trend that could be related to the site characteristics. Interestingly, two pristine freshwater sites formed a subgroup within one of the larger clusters. Thus far the bamA gene has only been examined within the context of contaminated environments, however, this study demonstrates that the bamA gene is also detected in uncontaminated sites. The widespread presence of the bamA gene in diverse environments suggests that the anaerobic benzoyl-CoA pathway plays an important role in the global carbon cycle that has thus far been understudied.
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Affiliation(s)
- Abigail W Porter
- Department of Environmental Science, School of Biological and Environmental Sciences, Rutgers University New Brunswick, NJ, USA
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Anaerobic benzene oxidation via phenol in Geobacter metallireducens. Appl Environ Microbiol 2013; 79:7800-6. [PMID: 24096430 DOI: 10.1128/aem.03134-13] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (<0.5 μM) of phenol accumulated in cultures of Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with (18)O during growth in H2(18)O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation.
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Liang X, Devine CE, Nelson J, Sherwood Lollar B, Zinder S, Edwards EA. Anaerobic conversion of chlorobenzene and benzene to CH4 and CO2 in bioaugmented microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:2378-85. [PMID: 23360185 DOI: 10.1021/es3043092] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chlorobenzene is a widespread groundwater contaminant found at many industrial sites. Reductive dechlorination of chlorobenzene requires input of electron donor and results in problematic accumulation of benzene, which is more toxic than chlorobenzene. We hypothesized that coupling a culture capable of reductive dechlorination of chlorobenzene to benzene with a second benzene-degrading methanogenic culture would completely detoxify chlorobenzene. To this end, active chlorobenzene-dechlorinating microcosms that were producing benzene were inoculated with a previously described enriched methanogenic benzene-degrading consortium. The combination resulted in the transformation of chlorobenzene via benzene to the nontoxic degradation products, CO2 and CH4. Sustainable degradation of chlorobenzene and benzene was observed in the microcosms and was further confirmed by shifts in the carbon isotopic ratios of chlorobenzene and benzene during degradation. Moreover, we could show that benzene derived electrons fueled chlorobenzene dechlorination removing the need to provide exogenous electron donor. The results have promising implications for sustainable bioremediation of sites contaminated with chlorinated benzenes and benzene.
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Affiliation(s)
- Xiaoming Liang
- Department of Chemical Engineering and Applied Chemistry, University of Toronto , Toronto, ON M5S 3E5, Canada
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Abstract
The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 10(9) and 8.4 × 10(9) cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 10(9) cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated.
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Berdugo-Clavijo C, Dong X, Soh J, Sensen CW, Gieg LM. Methanogenic biodegradation of two-ringed polycyclic aromatic hydrocarbons. FEMS Microbiol Ecol 2012; 81:124-33. [DOI: 10.1111/j.1574-6941.2012.01328.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 01/21/2012] [Accepted: 01/31/2012] [Indexed: 11/29/2022] Open
Affiliation(s)
- Carolina Berdugo-Clavijo
- Petroleum Microbiology Research Group, Department of Biological Sciences; University of Calgary; Calgary; AB; Canada
| | - Xiaoli Dong
- Visual Genomics Centre, Faculty of Medicine; University of Calgary; Calgary; AB; Canada
| | - Jung Soh
- Visual Genomics Centre, Faculty of Medicine; University of Calgary; Calgary; AB; Canada
| | - Christoph W. Sensen
- Visual Genomics Centre, Faculty of Medicine; University of Calgary; Calgary; AB; Canada
| | - Lisa M. Gieg
- Petroleum Microbiology Research Group, Department of Biological Sciences; University of Calgary; Calgary; AB; Canada
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Masumoto H, Kurisu F, Kasuga I, Tourlousse DM, Furumai H. Complete mineralization of benzene by a methanogenic enrichment culture and effect of putative metabolites on the degradation. CHEMOSPHERE 2012; 86:822-828. [PMID: 22205046 DOI: 10.1016/j.chemosphere.2011.11.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 11/22/2011] [Accepted: 11/22/2011] [Indexed: 05/31/2023]
Abstract
Microbial degradation of benzene under anaerobic conditions plays an important role in remediation of contaminated sites but the microorganisms and metabolic pathways involved remain poorly understood. In this study, we evaluated degradation of benzene by a methanogenic enrichment culture obtained from non-contaminated lotus field soil, alone and in the presence of several putative metabolic intermediates, that is, toluene, benzoate and phenol. Using stable isotope ((13)C) labeled substrate, benzene was shown to be degraded almost completely to equimolar concentrations of methane and carbon dioxide, without detectable accumulation of extracellular metabolites. Concurrently, toluene, benzoate and phenol were also effectively mineralized, but probably by microorganisms other than the benzene degraders. The latter included Hasda-A, which is putative benzene-degrading deltaproteobacterium present in the culture. While toluene and benzoate did not affect benzene degradation, phenol had a moderate inhibitory effect although it was not a major metabolic intermediate of benzene in our culture. Finally, 4-hydroxycoumarin was detected as a compound formed from phenol but further experiments are required to elucidate its relationship to degradation of phenol.
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Affiliation(s)
- Hiroki Masumoto
- Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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van der Zaan BM, Saia FT, Stams AJM, Plugge CM, de Vos WM, Smidt H, Langenhoff AAM, Gerritse J. Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae as dominant benzene degraders and evidence for a syntrophic process. Environ Microbiol 2012; 14:1171-81. [PMID: 22296107 DOI: 10.1111/j.1462-2920.2012.02697.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a syntrophic interaction, and that benzene can be degraded in syntrophy by consortia with various electron acceptors in the same culture. The benzene-degrading microorganisms were identified by DNA-stable isotope probing with [U-(13) C]-labelled benzene, and the effect of different electron donors and acceptors on benzene degradation was investigated. The degradation rate constant of benzene with nitrate (0.7 day(-1) ) was higher than reported previously. In the absence of nitrate, the microbial community was able to use sulfate, chlorate or ferric iron as electron acceptor. Bacteria belonging to the Peptococcaceae were identified as dominant benzene consumers, but also those related to Rhodocyclaceae and Burkholderiaceae were found to be associated with the anaerobic benzene degradation process. The benzene degradation activity in the chemostat was associated with microbial growth in biofilms. This, together with the inhibiting effect of hydrogen and the ability to degrade benzene with different electron acceptors, suggests that benzene was degraded via a syntrophic process.
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Li YN, Porter A, Mumford A, Zhao XH, Young L. Bacterial community structure and bamA gene diversity in anaerobic degradation of toluene and benzoate under denitrifying conditions. J Appl Microbiol 2012; 112:269-79. [DOI: 10.1111/j.1365-2672.2011.05213.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fowler SJ, Dong X, Sensen CW, Suflita JM, Gieg LM. Methanogenic toluene metabolism: community structure and intermediates. Environ Microbiol 2011; 14:754-64. [PMID: 22040260 DOI: 10.1111/j.1462-2920.2011.02631.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Toluene is a model compound used to study the anaerobic biotransformation of aromatic hydrocarbons. Reports indicate that toluene is transformed via fumarate addition to form benzylsuccinate or by unknown mechanisms to form hydroxylated intermediates under methanogenic conditions. We investigated the mechanism(s) of syntrophic toluene metabolism by a newly described methanogenic enrichment from a gas condensate-contaminated aquifer. Pyrosequencing of 16S rDNA revealed that the culture was comprised mainly of Clostridiales. The predominant methanogens affiliated with the Methanomicrobiales. Methane production from toluene ranged from 72% to 79% of that stoichiometrically predicted. Isotope studies using (13)C(7) toluene showed that benzylsuccinate and benzoate transiently accumulated revealing that members of this consortium can catalyse fumarate addition and subsequent reactions. Detection of a BssA gene fragment in this culture further supported fumarate addition as a mechanism of toluene activation. Transient formation of cresols, benzylalcohol, hydroquinone and methylhydroquinone suggested alternative mechanism(s) for toluene metabolism. However, incubations of the consortium with (18)O-H(2)O showed that the hydroxyl group in these metabolites did not originate from water and abiotic control experiments revealed abiotic formation of hydroxylated species due to reactions of toluene with sulfide and oxygen. Our results suggest that toluene is activated by fumarate addition, presumably by the dominant Clostridiales.
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Affiliation(s)
- S Jane Fowler
- Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4
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Liang X, Howlett MR, Nelson JL, Grant G, Dworatzek S, Lacrampe-Couloume G, Zinder SH, Edwards EA, Sherwood Lollar B. Pathway-dependent isotope fractionation during aerobic and anaerobic degradation of monochlorobenzene and 1,2,4-trichlorobenzene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:8321-8327. [PMID: 21851082 DOI: 10.1021/es201224x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Stable carbon isotope fractionation is a valuable tool for monitoring natural attenuation and to establish the fate of groundwater contaminants. In this study, we measured carbon isotope fractionation during aerobic and anaerobic degradation of two chlorinated benzenes: monochlorobenzene (MCB) and 1,2,4-trichlorobenzene (1,2,4-TCB). MCB isotope fractionation was measured in anaerobic methanogenic microcosms, while 1,2,4-TCB isotope experiments were carried out in both aerobic and anaerobic microcosms. Large isotope fractionation was observed in both the anaerobic microcosm experiments. Enrichment factors (ε) for anaerobic reductive dechlorination of MCB and 1,2,4-TCB were -5.0‰ ± 0.2‰ and -3.0‰ ± 0.4‰, respectively. In contrast, no significant isotope fractionation was found during aerobic microbial degradation of 1,2,4-TCB. The cleavage of a C-Cl σ bond occurs during anaerobic reductive dechlorination of MCB and 1,2,4-TCB, while no σ bond cleavage is involved during aerobic degradation via dioxygenase. The difference in isotope fractionation for aerobic versus anaerobic biodegradation of MCB and 1,2,4-TCB can be explained by the difference in the initial step of aerobic versus anaerobic biodegradation pathways.
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Affiliation(s)
- Xiaoming Liang
- Department of Geology, University of Toronto , Toronto, Ontario M5S 3B1, Canada
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Holmes DE, Risso C, Smith JA, Lovley DR. Anaerobic oxidation of benzene by the hyperthermophilic archaeon Ferroglobus placidus. Appl Environ Microbiol 2011; 77:5926-33. [PMID: 21742914 PMCID: PMC3165377 DOI: 10.1128/aem.05452-11] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/27/2011] [Indexed: 11/20/2022] Open
Abstract
Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [(14)C]benzene to [(14)C]carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism, and [(14)C]benzoate was produced from [(14)C]benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not upregulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- than in benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much-needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms.
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Affiliation(s)
- Dawn E Holmes
- Department of Microbiology, 203N Morrill Science Center IVN, University of Massachusetts-Amherst, Amherst, MA 01003, USA.
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Parisi VA, Brubaker GR, Zenker MJ, Prince RC, Gieg LM, Da Silva MLB, Alvarez PJJ, Suflita JM. Field metabolomics and laboratory assessments of anaerobic intrinsic bioremediation of hydrocarbons at a petroleum-contaminated site. Microb Biotechnol 2011; 2:202-12. [PMID: 21261914 PMCID: PMC3815840 DOI: 10.1111/j.1751-7915.2009.00077.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Field metabolomics and laboratory assays were used to assess the in situ anaerobic attenuation of hydrocarbons in a contaminated aquifer underlying a former refinery. Benzene, ethylbenzene, 2-methylnaphthalene, 1,2,4- and 1,3,5-trimethylbenzene were targeted as contaminants of greatest regulatory concern (COC) whose intrinsic remediation has been previously reported. Metabolite profiles associated with anaerobic hydrocarbon decay revealed the microbial utilization of alkylbenzenes, including the trimethylbenzene COC, PAHs and several n-alkanes in the contaminated portions of the aquifer. Anaerobic biodegradation experiments designed to mimic in situ conditions showed no loss of exogenously amended COC; however, a substantive rate of endogenous electron acceptor reduction was measured (55 ± 8 µM SO(4) day(-1)). An assessment of hydrocarbon loss in laboratory experiments relative to a conserved internal marker revealed that non-COC hydrocarbons were being metabolized. Purge and trap analysis of laboratory assays showed a substantial loss of toluene, m- and o-xylene, as well as several alkanes (C(6)-C(12)). Multiple lines of evidence suggest that benzene is persistent under the prevailing site anaerobic conditions. We could find no in situ benzene intermediates (phenol or benzoate), the parent molecule proved recalcitrant in laboratory assays and low copy numbers of Desulfobacterium were found, a genus previously implicated in anaerobic benzene biodegradation. This study also showed that there was a reasonable correlation between field and laboratory findings, although with notable exception. Thus, while the intrinsic anaerobic bioremediation was clearly evident at the site, non-COC hydrocarbons were preferentially metabolized, even though there was ample literature precedence for the biodegradation of the target molecules.
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Affiliation(s)
- Victoria A Parisi
- Department of Botany and Microbiology and Institute for Energy and Environment, University of Oklahoma, Norman, Oklahoma 73019, USA
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38
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Cupples AM. The use of nucleic acid based stable isotope probing to identify the microorganisms responsible for anaerobic benzene and toluene biodegradation. J Microbiol Methods 2011; 85:83-91. [DOI: 10.1016/j.mimet.2011.02.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/18/2011] [Accepted: 02/18/2011] [Indexed: 11/26/2022]
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Abstract
Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation.
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Affiliation(s)
- Carsten Vogt
- Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
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40
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Meckenstock RU, Mouttaki H. Anaerobic degradation of non-substituted aromatic hydrocarbons. Curr Opin Biotechnol 2011; 22:406-14. [PMID: 21398107 DOI: 10.1016/j.copbio.2011.02.009] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 02/09/2011] [Accepted: 02/17/2011] [Indexed: 11/19/2022]
Abstract
Aromatic hydrocarbons are among the most prevalent organic pollutants in the environment. Their removal from contaminated systems is of great concern because of the high toxicity effect on living organisms including humans. Aerobic degradation of aromatic hydrocarbons has been intensively studied and is well understood. However, many aromatics end up in habitats devoid of molecular oxygen. Nevertheless, anaerobic degradation using alternative electron acceptors is much less investigated. Here, we review the recent literature and very early progress in the elucidation of anaerobic degradation of non-substituted monocyclic (i.e. benzene) and polycyclic aromatic hydrocarbons (PAH such as naphthalene and phenanthrene). A focus will be on benzene and naphthalene as model compounds. This review concerns the microbes involved, the biochemistry of the initial activation and subsequent enzyme reactions involved in the pathway.
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Affiliation(s)
- Rainer U Meckenstock
- Institute for Groundwater Ecology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
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Staats M, Braster M, Röling WF. Molecular diversity and distribution of aromatic hydrocarbon-degrading anaerobes across a landfill leachate plume. Environ Microbiol 2011; 13:1216-27. [DOI: 10.1111/j.1462-2920.2010.02421.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abu Laban N, Selesi D, Rattei T, Tischler P, Meckenstock RU. Identification of enzymes involved in anaerobic benzene degradation by a strictly anaerobic iron-reducing enrichment culture. Environ Microbiol 2011; 12:2783-96. [PMID: 20545743 DOI: 10.1111/j.1462-2920.2010.02248.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anaerobic benzene degradation was studied with a highly enriched iron-reducing culture (BF) composed of mainly Peptococcaceae-related Gram-positive microorganisms. The proteomes of benzene-, phenol- and benzoate-grown cells of culture BF were compared by SDS-PAGE. A specific benzene-expressed protein band of 60 kDa, which could not be observed during growth on phenol or benzoate, was subjected to N-terminal sequence analysis. The first 31 amino acids revealed that the protein was encoded by ORF 138 in the shotgun sequenced metagenome of culture BF. ORF 138 showed 43% sequence identity to phenylphosphate carboxylase subunit PpcA of Aromatoleum aromaticum strain EbN1. A LC/ESI-MS/MS-based shotgun proteomic analysis revealed other specifically benzene-expressed proteins with encoding genes located adjacent to ORF 138 on the metagenome. The protein products of ORF 137, ORF 139 and ORF 140 showed sequence identities of 37% to phenylphosphate carboxylase PpcD of A. aromaticum strain EbN1, 56% to benzoate-CoA ligase (BamY) of Geobacter metallireducens and 67% to 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX) of A. aromaticum strain EbN1 respectively. These genes are proposed as constituents of a putative benzene degradation gene cluster (∼ 17 kb) composed of carboxylase-related genes. The identified gene sequences suggest that the initial activation reaction in anaerobic benzene degradation is probably a direct carboxylation of benzene to benzoate catalysed by putative anaerobic benzene carboxylase (Abc). The putative Abc probably consists of several subunits, two of which are encoded by ORFs 137 and 138, and belongs to a family of carboxylases including phenylphosphate carboxylase (Ppc) and 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX).
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Affiliation(s)
- Nidal Abu Laban
- Helmholtz Zentrum München - German Research Center for Environmental Health, Institute of Groundwater Ecology, Ingolstädter Landstrasse 1, D-85764, Neuherberg, Germany
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Dou J, Ding A, Liu X, Du Y, Deng D, Wang J. Anaerobic benzene biodegradation by a pure bacterial culture of Bacillus cereus under nitrate reducing conditions. J Environ Sci (China) 2010; 22:709-715. [PMID: 20608507 DOI: 10.1016/s1001-0742(09)60167-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A pure culture using benzene as sole carbon and energy sources was isolated by screening procedure from gasoline contaminated soil. The analysis of the 16S rDNA gene sequence, morpholpgical and physiological characteristics showed that the isolated strain was a member of genus Bacillus cereus. The biodegradation performance of benzene by B. cereus was evaluated, and the results showed that benzene could be efficiently biodegraded when the initial benzene concentration was below 150 mg/L. The metabolites of anaerobic nitrate-dependent benzene oxidation by strain B. cereus were identified as phenol and benzoate. The results of substrate interaction between binary combinations for benzene, phenol and benzoate showed that the simultaneous presence of benzene stimulated the degradation of benzoate, whereas the addition of benzene inhibited the degradation of phenol. Benzene degradation by B. cereus was enhanced by the addition of phenol and benzoate, the enhanced effects were more pronounced at higher concentration. To our knowledge, this is the first report that the isolated bacterial culture of B. cereus can efficiently degraded benzene under nitrate reducing conditions.
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Affiliation(s)
- Junfeng Dou
- College of Water Sciences, Beijing Normal University, Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China.
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Makris KC, Andra SS, Hardy M, Sarkar D, Datta R, Bach SBH, Mullens CP. Nitrous oxide supersaturation at the liquid/air interface of animal waste. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2009; 157:3508-3513. [PMID: 19573962 DOI: 10.1016/j.envpol.2009.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 05/18/2009] [Accepted: 06/03/2009] [Indexed: 05/28/2023]
Abstract
Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N(2)O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N(2)O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N(2)O supersaturation at the liquid/air interface. The concentration of dissolved N(2)O in poultry litter (PL) aqueous suspensions at 25 degrees C was 0.36 microg N(2)O mL(-1), at least an order of magnitude greater than that measured in water in equilibrium with ambient air, suggesting N(2)O supersaturation. There was a nonlinear increase in the N(2)O Henry constants of PL from 2810 atm/mole fraction at 35 degrees C to 17 300 atm/mole fraction at 41 degrees C. The extremely high N(2)O Henry constants were partially ascribed to N(2)O complexation with aromatic moieties. Complexed N(2)O structures were unstable at temperatures > 35 degrees C, supplying the headspace with additional free N(2)O concentrations.
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Affiliation(s)
- Konstantinos C Makris
- Cyprus International Institute for the Environment and Public Health in association with the Harvard School of Public Health, 5 Iroon Street, Nicosia 1105, Cyprus.
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Benndorf D, Vogt C, Jehmlich N, Schmidt Y, Thomas H, Woffendin G, Shevchenko A, Richnow HH, von Bergen M. Improving protein extraction and separation methods for investigating the metaproteome of anaerobic benzene communities within sediments. Biodegradation 2009; 20:737-50. [PMID: 19381451 PMCID: PMC2847156 DOI: 10.1007/s10532-009-9261-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 04/01/2009] [Indexed: 11/23/2022]
Abstract
BTEX compounds such as benzene are frequent soil and groundwater contaminants that are easily biodegraded under oxic conditions by bacteria. In contrast, benzene is rather recalcitrant under anaerobic conditions. The analysis of anoxic degradation is often hampered by difficult sampling conditions, limited amounts of biomass and interference of matrix compounds with proteomic approaches. In order to improve the procedure for protein extraction we established a scheme consisting of the following steps: dissociation of cells from lava granules, cell lysis by ultrasonication and purification of proteins by phenol extraction. The 2D-gels revealed a resolution of about 240 proteins spots and the spot patterns showed strong matrix dependence, but still differences were detectable between the metaproteomes obtained after growth on benzene and benzoate. Using direct data base search as well as de novo sequencing approaches we were able to identify several proteins. An enoyl-CoA hydratase with cross species homology to Azoarcus evansii, is known to be involved in the anoxic degradation of xenobiotics. Thereby the identification confirmed that this procedure has the capacity to analyse the metaproteome of an anoxic living microbial community.
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Affiliation(s)
- Dirk Benndorf
- Department of Proteomics, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
- Bioprocess Engineering, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Nico Jehmlich
- Department of Proteomics, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Yvonne Schmidt
- Department of Proteomics, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Henrik Thomas
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Gary Woffendin
- Thermo Fisher, Stafford House, Boundary Way, Hemel Hempstead, HP2 7GE UK
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Hans-Hermann Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Martin von Bergen
- Department of Proteomics, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
- Department of Metabolomics, Helmholtz Centre for Environmental Research—UFZ, Permoserstr. 15, 04318 Leipzig, Germany
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46
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Fischer A, Gehre M, Breitfeld J, Richnow HH, Vogt C. Carbon and hydrogen isotope fractionation of benzene during biodegradation under sulfate-reducing conditions: a laboratory to field site approach. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:2439-2447. [PMID: 19603470 DOI: 10.1002/rcm.4049] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The microbial carbon and hydrogen isotope fractionation of benzene under sulfate-reducing conditions was investigated within systems of increasing complexity: (i) batch laboratory microcosms, (ii) a groundwater-percolated column system, and (iii) an aquifer transect. Recent molecular biological studies indicate that, at least in the laboratory microcosms and the column system, benzene is degraded by similar bacterial communities. Carbon and hydrogen enrichment factors (epsilon(C), epsilon(H)) obtained from laboratory microcosms and from the column study varied significantly although experiments were performed under similar redox and temperature conditions. Thus, enrichment factors for only a single element could not be used to distinguish benzene degradation under sulfate-reducing conditions from other redox conditions. In contrast, using correlation of changes of hydrogen vs. carbon isotope ratios (Lambda = Delta delta(2)H/Delta delta(13)C), similar Lambda-values were derived for the benzene biodegradation under sulfate-reducing conditions in all three experimental systems (Lambda(laboratory microcosms) = 23 +/- 5, Lambda(column) = 28 +/- 3, Lambda(aquifer) = 24 +/- 2), showing the robustness of the two-dimensional compound-specific stable isotope analysis (2D-CSIA) for elucidating distinct biodegradation pathways. Comparing carbon and hydrogen isotope fractionation data from recent studies, an overlap in Lambda-values was observed for benzene biodegradation under sulfate-reducing (Lambda = 23 +/- 5 to Lambda = 29 +/- 3) and methanogenic (Lambda = 28 +/- 1 to Lambda = 39 +/- 5) conditions, indicating a similar initial benzene reaction mechanism for both electron-acceptor conditions.
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Affiliation(s)
- Anko Fischer
- UFZ-Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, 04318 Leipzig, Germany
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Abu Laban N, Selesi D, Jobelius C, Meckenstock RU. Anaerobic benzene degradation by Gram-positive sulfate-reducing bacteria. FEMS Microbiol Ecol 2009; 68:300-11. [PMID: 19416354 DOI: 10.1111/j.1574-6941.2009.00672.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Despite its high chemical stability, benzene is known to be biodegradable with various electron acceptors under anaerobic conditions. However, our understanding of the initial activation reaction and the responsible prokaryotes is limited. In the present study, we enriched a bacterial culture that oxidizes benzene to carbon dioxide under sulfate-reducing conditions. Community analysis using terminal restriction fragment length polymorphism, 16S rRNA gene sequencing and FISH revealed 95% dominance of one phylotype that is affiliated to the Gram-positive bacterial genus Pelotomaculum showing that sulfate-reducing Gram-positive bacteria are involved in anaerobic benzene degradation. In order to get indications of the initial activation mechanism, we tested the substrate utilization, performed cometabolism tests and screened for putative metabolites. Phenol, toluene, and benzoate could not be utilized as alternative carbon sources by the benzene-degrading culture. Cometabolic degradation experiments resulted in retarded rates of benzene degradation in the presence of phenol whereas toluene had no effect on benzene metabolism. Phenol, 2-hydroxybenzoate, 4-hydroxybenzoate, and benzoate were identified as putative metabolites in the enrichment culture. However, hydroxylated aromatics were shown to be formed abiotically. Thus, the finding of benzoate as an intermediate compound supports a direct carboxylation of benzene as the initial activation mechanism but additional reactions leading to its formation cannot be excluded definitely.
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Affiliation(s)
- Nidal Abu Laban
- Helmholtz Zentrum München-German Research Center for Environmental Health, Institute of Groundwater Ecology, Neuherberg, Germany
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48
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Fung JM, Weisenstein BP, Mack EE, Vidumsky JE, Ei TA, Zinder SH. Reductive dehalogenation of dichlorobenzenes and monochlorobenzene to benzene in microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:2302-7. [PMID: 19452878 DOI: 10.1021/es802131d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Anaerobic microcosms were constructed using sediments from a historically chlorobenzene-contaminated site and were provided with yeast extract as an electron donor. In these methanogenic microcosms, all three isomers of dichlorobenzene (DCB) were reductively dehalogenated to monochlorobenzene (MCB) when added together or individually, with 1,2-DCB dehalogenation being the most rapid and 1,4-DCB the slowest. When nearly all of the DCBs were consumed, benzene was detected and its accumulation was concomitant with MCB disappearance. Small amounts of toluene were also detected along with benzene. Subsequent MCB doses were also converted to benzene, and benzene reached levels in excess of 5000 micromol/L in some microcosms. An initial DCB dose stimulated, and in some cases was necessary for, MCB dehalogenation. Subsequent doses of DCB or MCB were dehalogenated more rapidly than previous ones, consistent with a growth-related process. Addition of a ca. 4% inoculum from microcosms that had consumed DCBs or MCB stimulated DCB and MCB dehalogenation in fresh microcosms, also indicative of growth and suggests thatthe chlorobenzene-dehalogenating microorganisms in these microcosms are candidates for bioaugmentation at anaerobic DCB or MCB contaminated sites. These studies add to evidence that benzene production from chlorobenzenes needs to be considered when modeling processes at contaminated sites.
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Affiliation(s)
- Jennifer M Fung
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, New York 14853, USA
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49
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Daugulis AJ. A survey of bioengineering research in Canada-2007. Biotechnol Prog 2009; 24:795-806. [PMID: 19194891 DOI: 10.1002/btpr.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Research activity in bioengineering at Canadian universities has been surveyed. Details were provided by chemical engineering departments in response to a common request for information on activities by individual researchers and for key publications. The information provided has been grouped by topics within the broad theme of "Bioengineering," and contributions from individual departments have been summarized within these topics. Although many aspects of bioengineering research are being pursued in Canada, it would appear as though environmental biotechnology, biomaterials, and tissue/cell culture are the most active areas under investigation.
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Affiliation(s)
- Andrew J Daugulis
- Dept. of Chemical Engineering, Queen's University, Kingston, ON, Canada K7L 3N6.
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50
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Selesi D, Meckenstock RU. Anaerobic degradation of the aromatic hydrocarbon biphenyl by a sulfate-reducing enrichment culture. FEMS Microbiol Ecol 2009; 68:86-93. [PMID: 19187215 DOI: 10.1111/j.1574-6941.2009.00652.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The aromatic hydrocarbon biphenyl is a widely distributed environmental pollutant. Whereas the aerobic degradation of biphenyl has been extensively studied, knowledge of the anaerobic biphenyl-oxidizing bacteria and their biochemical degradation pathway is scarce. Here, we report on an enrichment culture that oxidized biphenyl completely to carbon dioxide under sulfate-reducing conditions. The biphenyl-degrading culture was dominated by two distinct bacterial species distantly affiliated with the Gram-positive genus Desulfotomaculum. Moreover, the enrichment culture has the ability to grow with benzene and a mixture of anthracene and phenanthrene as the sole source of carbon, but here the microbial community composition differed substantially from the biphenyl-grown culture. Biphenyl-4-carboxylic acid was identified as an intermediate in the biphenyl-degrading culture. Moreover, 4-fluorobiphenyl was converted cometabolically with biphenyl because in addition to the biphenyl-4-carboxylic acid, a compound identified as its fluorinated analog was observed. These findings are consistent with the general pattern in the anaerobic catabolism of many aromatic hydrocarbons where carboxylic acids are found to be central metabolites.
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Affiliation(s)
- Drazenka Selesi
- Institute of Groundwater Ecology, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany
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