1
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Pirete LDM, Camargo FP, Grosseli GM, Sakamoto IK, Fadini PS, Silva EL, Varesche MBA. Microbial diversity and metabolic inference of diclofenac removal in optimised batch heterotrophic-denitrifying conditions by means of factorial design. ENVIRONMENTAL TECHNOLOGY 2024; 45:2847-2866. [PMID: 36927407 DOI: 10.1080/09593330.2023.2192365] [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: 09/26/2022] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Using the Response Surface Methodology (RSM) and Rotational Central Composite Design (RCCD), this study evaluated the removal of DCF under denitrifying conditions, with ethanol as cosubstrate, in batch reactors, being 1 L Erlenmeyer flasks (330 mL of reactional volume) containing Dofing medium and kept under agitation at 130 rpm and incubated at mesophilic temperature (30 °C). It considered the individual and multiple effects of the variables: nitrate (130 - 230 mg NO3- L-1), DCF (60-100 µg DCF L-1) and ethanol (130 - 230 mg EtOH L-1). The highest drug removal efficiency (17.5%) and total nitrate removal were obtained at 176.6 ± 4.3 mg NO3 -L-1, 76.8 ± 3.7 µg DCF L-1, and 180.0 ± 2.5 mg EtOH L-1. Under such conditions, the addition of ethanol and nitrate was significant for the additional removal of diclofenac (p > 0.05). The prevalence of Rhodanobacter, Haliangium and Terrimonas in the inoculum biomass (activated sludge systems) was identified through the 16S rRNA gene sequencing. The potential of these genera to remove nitrate and degrade diclofenac was inferred, and the main enzymes potentially involved in this process were α-methylacyl-CoA racemase, long-chain fatty acid-CoA ligase, catalases and pseudoperoxidases.
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Affiliation(s)
- Luciana de Melo Pirete
- Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, São Carlos, Brazil
| | - Franciele Pereira Camargo
- Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, São Carlos, Brazil
| | | | - Isabel K Sakamoto
- Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, São Carlos, Brazil
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2
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Randazzo A, Venturi S, Tassi F. Soil processes modify the composition of volatile organic compounds (VOCs) from CO 2- and CH 4-dominated geogenic and landfill gases: A comprehensive study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171483. [PMID: 38458441 DOI: 10.1016/j.scitotenv.2024.171483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 02/06/2024] [Accepted: 03/03/2024] [Indexed: 03/10/2024]
Abstract
Degradation mechanisms affecting non-methane volatile organic compounds (VOCs) during gas uprising from different hypogenic sources to the surface were investigated through extensive sampling surveys in areas encompassing a high enthalpy hydrothermal system associated with active volcanism, a CH4-rich sedimentary basin and a municipal waste landfill. For a comprehensive framework, published data from medium-to-high enthalpy hydrothermal systems were also included. The investigated systems were characterised by peculiar VOC suites that reflected the conditions of the genetic environments in which temperature, contents of organic matter, and gas fugacity had a major role. Differences in VOC patterns between source (gas vents and landfill gas) and soil gases indicated VOC transformations in soil. Processes acting in soil preferentially degraded high-molecular weight alkanes with respect to the low-molecular weight ones. Alkenes and cyclics roughly behaved like alkanes. Thiophenes were degraded to a larger extent with respect to alkylated benzenes, which were more reactive than benzene. Furan appeared less degraded than its alkylated homologues. Dimethylsulfoxide was generally favoured with respect to dimethylsulfide. Limonene and camphene were relatively unstable under aerobic conditions, while α-pinene was recalcitrant. O-bearing organic compounds (i.e., aldehydes, esters, ketones, alcohols, organic acids and phenol) acted as intermediate products of the ongoing VOC degradations in soil. No evidence for the degradation of halogenated compounds and benzothiazole was observed. This study pointed out how soil degradation processes reduce hypogenic VOC emissions and the important role played by physicochemical and biological parameters on the effective VOC attenuation capacity of the soil.
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Affiliation(s)
- A Randazzo
- Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy; Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Firenze, Italy.
| | - S Venturi
- Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy; Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Firenze, Italy
| | - F Tassi
- Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy; Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Firenze, Italy
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3
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Zito P, Sihota N, Mohler RE, Podgorski DC. The formation, reactivity, and fate of oxygen-containing organic compounds in petroleum-contaminated groundwaters: A state of the science review and future research directions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170619. [PMID: 38311075 DOI: 10.1016/j.scitotenv.2024.170619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/30/2024] [Accepted: 01/30/2024] [Indexed: 02/06/2024]
Abstract
Hydrocarbon (HC) contamination in groundwater (GW) is a widespread environmental issue. Dissolved hydrocarbons in water are commonly utilized as an energy source by natural microbial communities, which can produce water soluble intermediate metabolite compounds, herein referred to as oxygen containing organic compounds (OCOCs), before achieving complete mineralization. This review aims to provide a comprehensive assessment of the literature focused on the state of the science for OCOCs detected and measured in GW samples collected from petroleum contaminated aquifers. In this review, we discuss and evaluate two hypotheses investigating OCOC formation, which are major points of contention in the freshwater oil spill community that need to be addressed. We reviewed over 150 articles compiling studies investigating OCOC formation and persistence to uncover knowledge gaps in the literature and studies that recommend quantitative and qualitative measurements of OCOCs in petroleum-contaminated aquifers. This review is essential because no consensus exists regarding specific compounds and related concerns. We highlight the knowledge gaps to progressing the discussion of hydrocarbon conversion products.
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Affiliation(s)
- Phoebe Zito
- Department of Chemistry, Chemical Analysis & Mass Spectrometry Facility, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, USA; Department of Chemistry, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA.
| | - Natasha Sihota
- Chevron Technical Center, 6001 Bollinger Canyon Road, San Ramon, CA 94583, USA
| | - Rachel E Mohler
- Chevron Technical Center, 100 Chevron Way, Richmond, CA 94801, USA
| | - David C Podgorski
- Department of Chemistry, Chemical Analysis & Mass Spectrometry Facility, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, USA; Pontchartrain Institute of Environmental Science, Shea Penland Coastal Education and Research Facility, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, USA; Department of Chemistry, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
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4
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Wu M, Li J, Lai CY, Leu AO, Sun S, Gu R, Erler DV, Liu L, Li L, Tyson GW, Yuan Z, McIlroy SJ, Guo J. Nitrate-driven anaerobic oxidation of ethane and butane by bacteria. THE ISME JOURNAL 2024; 18:wrad011. [PMID: 38365228 PMCID: PMC10811727 DOI: 10.1093/ismejo/wrad011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 02/18/2024]
Abstract
The short-chain gaseous alkanes (ethane, propane, and butane; SCGAs) are important components of natural gas, yet their fate in environmental systems is poorly understood. Microbially mediated anaerobic oxidation of SCGAs coupled to nitrate reduction has been demonstrated for propane, but is yet to be shown for ethane or butane-despite being energetically feasible. Here we report two independent bacterial enrichments performing anaerobic ethane and butane oxidation, respectively, coupled to nitrate reduction to dinitrogen gas and ammonium. Isotopic 13C- and 15N-labelling experiments, mass and electron balance tests, and metabolite and meta-omics analyses collectively reveal that the recently described propane-oxidizing "Candidatus Alkanivorans nitratireducens" was also responsible for nitrate-dependent anaerobic oxidation of the SCGAs in both these enrichments. The complete genome of this species encodes alkylsuccinate synthase genes for the activation of ethane/butane via fumarate addition. Further substrate range tests confirm that "Ca. A. nitratireducens" is metabolically versatile, being able to degrade ethane, propane, and butane under anoxic conditions. Moreover, our study proves nitrate as an additional electron sink for ethane and butane in anaerobic environments, and for the first time demonstrates the use of the fumarate addition pathway in anaerobic ethane oxidation. These findings contribute to our understanding of microbial metabolism of SCGAs in anaerobic environments.
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Affiliation(s)
- Mengxiong Wu
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Jie Li
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Chun-Yu Lai
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
- College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China
| | - Andy O Leu
- Centre for Microbiome Research, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology (QUT), Woolloongabba, Queensland, Australia
| | - Shengjie Sun
- Computational Science Program, The University of Texas at El Paso, El Paso, TX, United States
| | - Rui Gu
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Dirk V Erler
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Lian Liu
- Metabolomics Australia (Queensland Node), Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Lin Li
- Department of Physics, University of Texas at El Paso, El Paso, TX, United States
| | - Gene W Tyson
- Centre for Microbiome Research, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology (QUT), Woolloongabba, Queensland, Australia
| | - Zhiguo Yuan
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
- School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, China
| | - Simon J McIlroy
- Centre for Microbiome Research, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology (QUT), Woolloongabba, Queensland, Australia
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, St Lucia, Queensland 4072, Australia
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5
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Zehnle H, Laso-Pérez R, Lipp J, Riedel D, Benito Merino D, Teske A, Wegener G. Candidatus Alkanophaga archaea from Guaymas Basin hydrothermal vent sediment oxidize petroleum alkanes. Nat Microbiol 2023:10.1038/s41564-023-01400-3. [PMID: 37264141 DOI: 10.1038/s41564-023-01400-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 04/28/2023] [Indexed: 06/03/2023]
Abstract
Methanogenic and methanotrophic archaea produce and consume the greenhouse gas methane, respectively, using the reversible enzyme methyl-coenzyme M reductase (Mcr). Recently, Mcr variants that can activate multicarbon alkanes have been recovered from archaeal enrichment cultures. These enzymes, called alkyl-coenzyme M reductase (Acrs), are widespread in the environment but remain poorly understood. Here we produced anoxic cultures degrading mid-chain petroleum n-alkanes between pentane (C5) and tetradecane (C14) at 70 °C using oil-rich Guaymas Basin sediments. In these cultures, archaea of the genus Candidatus Alkanophaga activate the alkanes with Acrs and completely oxidize the alkyl groups to CO2. Ca. Alkanophaga form a deep-branching sister clade to the methanotrophs ANME-1 and are closely related to the short-chain alkane oxidizers Ca. Syntrophoarchaeum. Incapable of sulfate reduction, Ca. Alkanophaga shuttle electrons released from alkane oxidation to the sulfate-reducing Ca. Thermodesulfobacterium syntrophicum. These syntrophic consortia are potential key players in petroleum degradation in heated oil reservoirs.
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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.
| | - Rafael Laso-Pérez
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
- Biogeochemistry and Microbial Ecology Department, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
| | - Julius Lipp
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Dietmar Riedel
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - David Benito Merino
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Andreas Teske
- Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - 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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6
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Wegener G, Laso-Pérez R, Orphan VJ, Boetius A. Anaerobic Degradation of Alkanes by Marine Archaea. Annu Rev Microbiol 2022; 76:553-577. [PMID: 35917471 DOI: 10.1146/annurev-micro-111021-045911] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alkanes are saturated apolar hydrocarbons that range from its simplest form, methane, to high-molecular-weight compounds. Although alkanes were once considered biologically recalcitrant under anaerobic conditions, microbiological investigations have now identified several microbial taxa that can anaerobically degrade alkanes. Here we review recent discoveries in the anaerobic oxidation of alkanes with a specific focus on archaea that use specific methyl coenzyme M reductases to activate their substrates. Our understanding of the diversity of uncultured alkane-oxidizing archaea has expanded through the use of environmental metagenomics and enrichment cultures of syntrophic methane-, ethane-, propane-, and butane-oxidizing marine archaea with sulfate-reducing bacteria. A recently cultured group of archaea directly couples long-chain alkane degradation with methane formation, expanding the range of substrates used for methanogenesis. This article summarizes the rapidly growing knowledge of the diversity, physiology, and habitat distribution of alkane-degrading archaea. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Gunter Wegener
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rafael Laso-Pérez
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany.,Current affiliation: Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Victoria J Orphan
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Division of Geological and Planetary Sciences and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA;
| | - Antje Boetius
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany.,Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany;
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7
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Chen SC, Ji J, Popp D, Jaekel U, Richnow HH, Sievert SM, Musat F. Genome and proteome analyses show the gaseous alkane degrader Desulfosarcina sp. strain BuS5 as an extreme metabolic specialist. Environ Microbiol 2022; 24:1964-1976. [PMID: 35257474 DOI: 10.1111/1462-2920.15956] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 02/23/2022] [Indexed: 11/30/2022]
Abstract
The metabolic potential of the sulfate-reducing bacterium Desulfosarcina sp. strain BuS5, currently the only pure culture able to oxidize the volatile alkanes propane and butane without oxygen, was investigated via genomics, proteomics and physiology assays. Complete genome sequencing revealed that strain BuS5 encodes a single alkyl-succinate synthase, an enzyme which apparently initiates oxidation of both propane and butane. The formed alkyl-succinates are oxidized to CO2 via beta oxidation and the oxidative Wood-Ljungdahl pathways as shown by proteogenomics analyses. Strain BuS5 conserves energy via the canonical sulfate reduction pathway and electron bifurcation. An ability to utilize long-chain fatty acids, mannose and oligopeptides, suggested by automated annotation pipelines, was not supported by physiology assays and in-depth analyses of the corresponding genetic systems. Consistently, comparative genomics revealed a streamlined BuS5 genome with a remarkable paucity of catabolic modules. These results establish strain BuS5 as an exceptional metabolic specialist, able to grow only with propane and butane, for which we propose the name Desulfosarcina aeriophaga BuS5. This highly restrictive lifestyle, most likely the result of habitat-driven evolutionary gene loss, may provide D. aeriophaga BuS5 a competitive edge in sediments impacted by natural gas seeps. Etymology: Desulfosarcina aeriophaga, aério (Greek): gas; phágos (Greek): eater; D. aeriophaga: a gas eating or gas feeding Desulfosarcina.
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Affiliation(s)
- Song-Can Chen
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Jiaheng Ji
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Denny Popp
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | | | - Hans-Hermann Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Stefan M Sievert
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
| | - Florin Musat
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babeş-Bolyai University, Cluj-Napoca, Romania
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8
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Wang Y, Nguyen N, Lee SH, Wang Q, May JA, Gonzalez R, Cirino PC. Engineering Escherichia coli for anaerobic alkane activation: Biosynthesis of (1-methylalkyl)succinates. Biotechnol Bioeng 2021; 119:315-320. [PMID: 34633065 DOI: 10.1002/bit.27956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/28/2021] [Accepted: 10/03/2021] [Indexed: 11/11/2022]
Abstract
In anoxic environments, microbial activation of alkanes for subsequent metabolism occurs most commonly through the addition of fumarate to a subterminal carbon, producing an alkylsuccinate. Alkylsuccinate synthases are complex, multi-subunit enzymes that utilize a catalytic glycyl radical and require a partner, activating enzyme for hydrogen abstraction. While many genes encoding putative alkylsuccinate synthases have been identified, primarily from nitrate- and sulfate-reducing bacteria, few have been characterized and none have been reported to be functionally expressed in a heterologous host. Here, we describe the functional expression of the (1-methylalkyl)succinate synthase (Mas) system from Azoarcus sp. strain HxN1 in recombinant Escherichia coli. Mass spectrometry confirms anaerobic biosynthesis of the expected products of fumarate addition to hexane, butane, and propane. Maximum production of (1-methylpentyl)succinate is observed when masC, masD, masE, masB, and masG are all present on the expression plasmid; omitting masC reduces production by 66% while omitting any other gene eliminates production. Meanwhile, deleting iscR (encoding the repressor of the E. coli iron-sulfur cluster operon) improves product titer, as does performing the biotransformation at reduced temperature (18°C), both suggesting alkylsuccinate biosynthesis is largely limited by functional expression of this enzyme system.
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Affiliation(s)
- Yixi Wang
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Nam Nguyen
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Seung H Lee
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Qinxuan Wang
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Jeremy A May
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Ramon Gonzalez
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida, USA
| | - Patrick C Cirino
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
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9
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McLean JT, Benny A, Nolan MD, Swinand G, Scanlan EM. Cysteinyl radicals in chemical synthesis and in nature. Chem Soc Rev 2021; 50:10857-10894. [PMID: 34397045 DOI: 10.1039/d1cs00254f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nature harnesses the unique properties of cysteinyl radical intermediates for a diverse range of essential biological transformations including DNA biosynthesis and repair, metabolism, and biological photochemistry. In parallel, the synthetic accessibility and redox chemistry of cysteinyl radicals renders them versatile reactive intermediates for use in a vast array of synthetic applications such as lipidation, glycosylation and fluorescent labelling of proteins, peptide macrocyclization and stapling, desulfurisation of peptides and proteins, and development of novel therapeutics. This review provides the reader with an overview of the role of cysteinyl radical intermediates in both chemical synthesis and biological systems, with a critical focus on mechanistic details. Direct insights from biological systems, where applied to chemical synthesis, are highlighted and potential avenues from nature which are yet to be explored synthetically are presented.
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Affiliation(s)
- Joshua T McLean
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Alby Benny
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Mark D Nolan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Glenna Swinand
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Eoin M Scanlan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
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10
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Sengupta K, Pal S. A review on microbial diversity and genetic markers involved in methanogenic degradation of hydrocarbons: futuristic prospects of biofuel recovery from contaminated regions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:40288-40307. [PMID: 33844144 DOI: 10.1007/s11356-021-13666-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
Microbial activities within oil reservoirs have adversely impacted the world's majority of oil by lowering its quality, thereby increasing its recovery and refining cost. Moreover, conventional method of extraction leaves behind nearly two-thirds of the fossil fuels in the oil fields. This huge potential can be extracted if engineered methanogenic consortium is adapted to convert the hydrocarbons into natural gas. This process involves conversion of crude oil hydrocarbons into methanogenic substrates by syntrophic and fermentative bacteria, which are subsequently utilized by methanogens to produce methane. Microbial diversity of such environments supports the viability of this process. This review illuminates the potentials of abundant microbial groups such as Syntrophaceae, Anaerolineaceae, Clostridiales and Euryarchaeota in petroleum hydrocarbon-related environment, their genetic markers, biochemical process and omics-based bioengineering methods involved in methane generation. Increase in the copy numbers of catabolic genes during methanogenesis highlights the prospect of developing engineered biofuel recovery technology. Several lab-based methanogenic consortia from depleted petroleum reservoirs and microcosm studies so far would not be enough for field application without the advent of multi-omics-based technologies to trawl out the bottleneck parameters of the enhanced fuel recovery process. The adaptability of efficient consortium of versatile hydrocarbonoclastic and methanogenic microorganisms under environmental stress conditions is further needed to be investigated. The improved process might hold the potential of methane extraction from petroleum waste like oil tank and refinery sludge, oil field deposits, etc. What sounds as biodegradation could be a beginning of converting waste into wealth by recovery of stranded energy assets.
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Affiliation(s)
- Kriti Sengupta
- Bioenergy Group, Agharkar Research Institute, Pune, 411004, India
| | - Siddhartha Pal
- National Centre for Cell Science, Ganeshkhind, Pune, 411007, India.
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11
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Mitschke N, Eruçar G, Fsadni MH, Roberts AR, Sadeghi MM, Golding BT, Christoffers J, Wilkes H. Enantiopure 2,9‐Dideuterodecane – Preparation and Proof of Enantiopurity. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Nico Mitschke
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
- Institut für Chemie und Biologie des Meeres (ICBM) Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Gülsera Eruçar
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Miriam H. Fsadni
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Amy R. Roberts
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Majid M. Sadeghi
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Bernard T. Golding
- School of Natural & Environmental Sciences, Bedson Building Newcastle University NE1 7RU Newcastle upon Tyne UK
| | - Jens Christoffers
- Institut für Chemie Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM) Carl von Ossietzky Universität Oldenburg 26111 Oldenburg Germany
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12
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Drozdowska M, Tromans J, Zhang B, Jarling R, Wilkes H, Golding BT. Defining Pathways of Anaerobic Alkane Oxidation: Synthesis of Enantiomers of 4‐Methylalkanoic Acids and (2‐Methylalkyl)malonic Acids. ChemistrySelect 2021. [DOI: 10.1002/slct.202100415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marta Drozdowska
- School of Natural and Environmental Sciences – Chemistry Bedson Building Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Jay Tromans
- School of Natural and Environmental Sciences – Chemistry Bedson Building Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Bian Zhang
- BiBerChem Research Limited The Biosphere Drayman's Way, Newcastle Helix, Corporation Street Newcastle upon Tyne NE4 5BX UK
| | - René Jarling
- Organische Geochemie Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum Haus B228, Telegrafenberg 14473 Potsdam Germany
- Organic Geochemistry Institute for Chemistry and Biology of the Marine Environment (ICBM) Carl von Ossietzky University Oldenburg Carl-von-Ossietzky-Straße 9–11 D-26111 Oldenburg Germany
| | - Heinz Wilkes
- Organische Geochemie Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum Haus B228, Telegrafenberg 14473 Potsdam Germany
- Organic Geochemistry Institute for Chemistry and Biology of the Marine Environment (ICBM) Carl von Ossietzky University Oldenburg Carl-von-Ossietzky-Straße 9–11 D-26111 Oldenburg Germany
| | - Bernard T. Golding
- School of Natural and Environmental Sciences – Chemistry Bedson Building Newcastle University Newcastle upon Tyne NE1 7RU UK
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13
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Cakić N, Kopke B, Rabus R, Wilkes H. Suspect screening and targeted analysis of acyl coenzyme A thioesters in bacterial cultures using a high-resolution tribrid mass spectrometer. Anal Bioanal Chem 2021; 413:3599-3610. [PMID: 33881564 PMCID: PMC8141488 DOI: 10.1007/s00216-021-03318-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/14/2021] [Accepted: 03/30/2021] [Indexed: 11/20/2022]
Abstract
Analysis of acyl coenzyme A thioesters (acyl-CoAs) is crucial in the investigation of a wide range of biochemical reactions and paves the way to fully understand the concerned metabolic pathways and their superimposed networks. We developed two methods for suspect screening of acyl-CoAs in bacterial cultures using a high-resolution Orbitrap Fusion tribrid mass spectrometer. The methods rely on specific fragmentation patterns of the target compounds, which originate from the coenzyme A moiety. They make use of the formation of the adenosine 3′,5′-diphosphate key fragment (m/z 428.0365) and the neutral loss of the adenosine 3′-phosphate-5′-diphosphate moiety (506.9952) as preselection criteria for the detection of acyl-CoAs. These characteristic ions are generated either by an optimised in-source fragmentation in a full scan Orbitrap measurement or by optimised HCD fragmentation. Additionally, five different filters are included in the design of method. Finally, data-dependent MS/MS experiments on specifically preselected precursor ions are performed. The utility of the methods is demonstrated by analysing cultures of the denitrifying betaproteobacterium “Aromatoleum” sp. strain HxN1 anaerobically grown with hexanoate. We detected 35 acyl-CoAs in total and identified 24 of them by comparison with reference standards, including all 9 acyl-CoA intermediates expected to occur in the degradation pathway of hexanoate. The identification of additional acyl-CoAs provides insight into further metabolic processes occurring in this bacterium. The sensitivity of the method described allows detecting acyl-CoAs present in biological samples in highly variable abundances. Graphical abstract ![]()
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Affiliation(s)
- Nevenka Cakić
- Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany.
| | - Bernd Kopke
- Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Ralf Rabus
- General & Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Heinz Wilkes
- Organic Geochemistry, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
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14
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Shlimon A, Mansurbeg H, Othman R, Head I, Kjeldsen KU, Finster K. Identity and hydrocarbon degradation activity of enriched microorganisms from natural oil and asphalt seeps in the Kurdistan Region of Iraq (KRI). Biodegradation 2021; 32:251-271. [PMID: 33782778 DOI: 10.1007/s10532-021-09931-4] [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: 05/26/2020] [Accepted: 02/19/2021] [Indexed: 10/21/2022]
Abstract
A previous cultivation-independent investigation of the microbial community structure of natural oil and asphalt seeps in the Kurdistan Region of Iraq (KRI) revealed the dominance of uncultured bacterial taxa belonging to the phyla Deferribacterota and Coprothermobacterota and the orders Thermodesulfobacteriales, Thermales, and Burkholderiales. Here we report on a cultivation-dependent approach to identify members of these groups involved in hydrocarbon degradation in the KRI oil and asphalt seeps. For this purpose, we set up anoxic crude oil-degrading enrichment cultures based on cultivation media known to support the growth of members of the above-mentioned taxonomic groups. During 100-200 days incubation periods, nitrate-reducing and fermentative enrichments showed up to 90% degradation of C8-C17 alkanes and up to 28% degradation of C18-C33 alkanes along with aromatic hydrocarbons. Community profiling of the enrichment cultures showed that they were dominated by diverse bacterial taxa, which were rare in situ community members in the investigated seeps. Groups initially targeted by our approach were not enriched, possibly because their members are slow-growing and involved in the degradation of recalcitrant hydrocarbons. Nevertheless, the enriched taxa were taxonomically related to phylotypes recovered from hydrocarbon-impacted environments as well as to characterized bacterial isolates not previously known to be involved in hydrocarbon degradation. Marker genes (assA and bssA), diagnostic for fumarate addition-based anaerobic hydrocarbon degradation, were not detectable in the enrichment cultures by PCR. We conclude that hydrocarbon biodegradation in our enrichments occurred via unknown pathways and synergistic interactions among the enriched taxa. We suggest, that although not representing abundant populations in situ, studies of the cultured close relatives of these taxa will reveal an unrecognized potential for anaerobic hydrocarbon degradation, possibly involving poorly characterized mechanisms.
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Affiliation(s)
- Adris Shlimon
- Department of Biology, Soran University, Soran, Iraq. .,Section of Microbiology, Department of Biology, Aarhus University, Ny Munkegade 116, 8000, Aarhus, Denmark.
| | - Howri Mansurbeg
- Department of Petroleum Geoscience, Soran University, Soran, Iraq.,Department of Earth and Environmental Sciences, University of Windsor, Windsor, ON, Canada
| | - Rushdy Othman
- Department of Petroleum Geoscience, Soran University, Soran, Iraq
| | - Ian Head
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK
| | - Kasper U Kjeldsen
- Section of Microbiology, Department of Biology, Aarhus University, Ny Munkegade 116, 8000, Aarhus, Denmark
| | - Kai Finster
- Section of Microbiology, Department of Biology, Aarhus University, Ny Munkegade 116, 8000, Aarhus, Denmark
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15
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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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16
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Chen G, Widdel F, Musat F. Effect of energy deprivation on metabolite release by anaerobic marine naphthalene‐degrading sulfate‐reducing bacteria. Environ Microbiol 2020; 22:4057-4066. [DOI: 10.1111/1462-2920.15195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/02/2020] [Accepted: 08/09/2020] [Indexed: 01/18/2023]
Affiliation(s)
- Gao Chen
- Max Planck Institute for Marine Microbiology Celsiusstraße 1 Bremen D‐28359 Germany
- Department of Civil and Environmental Engineering University of Tennessee Knoxville, TN 37996 USA
| | - Friedrich Widdel
- Max Planck Institute for Marine Microbiology Celsiusstraße 1 Bremen D‐28359 Germany
| | - Florin Musat
- Max Planck Institute for Marine Microbiology Celsiusstraße 1 Bremen D‐28359 Germany
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research – UFZ, Permoserstr., 15, 04318 Leipzig Germany
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17
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Raggi L, García-Guevara F, Godoy-Lozano EE, Martínez-Santana A, Escobar-Zepeda A, Gutierrez-Rios RM, Loza A, Merino E, Sanchez-Flores A, Licea-Navarro A, Pardo-Lopez L, Segovia L, Juarez K. Metagenomic Profiling and Microbial Metabolic Potential of Perdido Fold Belt (NW) and Campeche Knolls (SE) in the Gulf of Mexico. Front Microbiol 2020; 11:1825. [PMID: 32903729 PMCID: PMC7438803 DOI: 10.3389/fmicb.2020.01825] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/10/2020] [Indexed: 01/04/2023] Open
Abstract
The Gulf of Mexico (GoM) is a particular environment that is continuously exposed to hydrocarbon compounds that may influence the microbial community composition. We carried out a metagenomic assessment of the bacterial community to get an overall view of this geographical zone. We analyzed both taxonomic and metabolic markers profiles to explain how the indigenous GoM microorganims participate in the biogeochemical cycling. Two geographically distant regions in the GoM, one in the north-west (NW) and one in the south-east (SE) of the GoM were analyzed and showed differences in their microbial composition and metabolic potential. These differences provide evidence the delicate equilibrium that sustains microbial communities and biogeochemical cycles. Based on the taxonomy and gene groups, the NW are more oxic sediments than SE ones, which have anaerobic conditions. Both water and sediments show the expected sulfur, nitrogen, and hydrocarbon metabolism genes, with particularly high diversity of the hydrocarbon-degrading ones. Accordingly, many of the assigned genera were associated with hydrocarbon degradation processes, Nitrospira and Sva0081 were the most abundant in sediments, while Vibrio, Alteromonas, and Alcanivorax were mostly detected in water samples. This basal-state analysis presents the GoM as a potential source of aerobic and anaerobic hydrocarbon degradation genes important for the ecological dynamics of hydrocarbons and the potential use for water and sediment bioremediation processes.
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Affiliation(s)
- Luciana Raggi
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.,CONACYT-Laboratorio de Biotecnología Acuícola, Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico
| | | | - E Ernestina Godoy-Lozano
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.,Centro de Investigación Sobre Enfermedades Infecciosas, Departamento de Bioinformática en Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico
| | | | | | | | - Antonio Loza
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Enrique Merino
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | - Alexei Licea-Navarro
- Laboratorio de Inmunología Molecular y Biotoxinas, Departamento de Innovación Biomedica, CICESE, Ensenada, Mexico
| | - Liliana Pardo-Lopez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Lorenzo Segovia
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Katy Juarez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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18
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Hahn CJ, Laso-Pérez R, Vulcano F, Vaziourakis KM, Stokke R, Steen IH, Teske A, Boetius A, Liebeke M, Amann R, Knittel K, Wegener G. " Candidatus Ethanoperedens," a Thermophilic Genus of Archaea Mediating the Anaerobic Oxidation of Ethane. mBio 2020; 11:e00600-20. [PMID: 32317322 PMCID: PMC7175092 DOI: 10.1128/mbio.00600-20] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 03/23/2020] [Indexed: 01/01/2023] Open
Abstract
Cold seeps and hydrothermal vents deliver large amounts of methane and other gaseous alkanes into marine surface sediments. Consortia of archaea and partner bacteria thrive on the oxidation of these alkanes and its coupling to sulfate reduction. The inherently slow growth of the involved organisms and the lack of pure cultures have impeded the understanding of the molecular mechanisms of archaeal alkane degradation. Here, using hydrothermal sediments of the Guaymas Basin (Gulf of California) and ethane as the substrate, we cultured microbial consortia of a novel anaerobic ethane oxidizer, "Candidatus Ethanoperedens thermophilum" (GoM-Arc1 clade), and its partner bacterium "Candidatus Desulfofervidus auxilii," previously known from methane-oxidizing consortia. The sulfate reduction activity of the culture doubled within one week, indicating a much faster growth than in any other alkane-oxidizing archaea described before. The dominance of a single archaeal phylotype in this culture allowed retrieval of a closed genome of "Ca. Ethanoperedens," a sister genus of the recently reported ethane oxidizer "Candidatus Argoarchaeum." The metagenome-assembled genome of "Ca. Ethanoperedens" encoded a complete methanogenesis pathway including a methyl-coenzyme M reductase (MCR) that is highly divergent from those of methanogens and methanotrophs. Combined substrate and metabolite analysis showed ethane as the sole growth substrate and production of ethyl-coenzyme M as the activation product. Stable isotope probing demonstrated that the enzymatic mechanism of ethane oxidation in "Ca. Ethanoperedens" is fully reversible; thus, its enzymatic machinery has potential for the biotechnological development of microbial ethane production from carbon dioxide.IMPORTANCE In the seabed, gaseous alkanes are oxidized by syntrophic microbial consortia that thereby reduce fluxes of these compounds into the water column. Because of the immense quantities of seabed alkane fluxes, these consortia are key catalysts of the global carbon cycle. Due to their obligate syntrophic lifestyle, the physiology of alkane-degrading archaea remains poorly understood. We have now cultivated a thermophilic, relatively fast-growing ethane oxidizer in partnership with a sulfate-reducing bacterium known to aid in methane oxidation and have retrieved the first complete genome of a short-chain alkane-degrading archaeon. This will greatly enhance the understanding of nonmethane alkane activation by noncanonical methyl-coenzyme M reductase enzymes and provide insights into additional metabolic steps and the mechanisms underlying syntrophic partnerships. Ultimately, this knowledge could lead to the biotechnological development of alkanogenic microorganisms to support the carbon neutrality of industrial processes.
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Affiliation(s)
| | - Rafael Laso-Pérez
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Francesca Vulcano
- K.G. Jebsen Centre for Deep Sea Research and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | - Runar Stokke
- K.G. Jebsen Centre for Deep Sea Research and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Ida Helene Steen
- K.G. Jebsen Centre for Deep Sea Research and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Andreas Teske
- The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Antje Boetius
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Manuel Liebeke
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rudolf Amann
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
| | - Katrin Knittel
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
| | - Gunter Wegener
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
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19
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Chen J, Liu YF, Zhou L, Irfan M, Hou ZW, Li W, Mbadinga SM, Liu JF, Yang SZ, Wu XL, Gu JD, Mu BZ. Long-chain n-alkane biodegradation coupling to methane production in an enriched culture from production water of a high-temperature oil reservoir. AMB Express 2020; 10:63. [PMID: 32266503 PMCID: PMC7138878 DOI: 10.1186/s13568-020-00998-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 03/21/2020] [Indexed: 11/18/2022] Open
Abstract
Paraffinic n-alkanes (C22–C30), crucial portions of residual oil, are generally considered to be difficult to be biodegraded owing to their general solidity at ambient temperatures and low water solubility, rendering relatively little known about metabolic processes in different methanogenic hydrocarbon-contaminated environments. Here, we established a methanogenic C22–C30 n-alkane-degrading enrichment culture derived from a high-temperature oil reservoir production water. During two-year incubation (736 days), unexpectedly significant methane production was observed. The measured maximum methane yield rate (164.40 μmol L−1 d−1) occurred during the incubation period from day 351 to 513. The nearly complete consumption (> 97%) of paraffinic n-alkanes and the detection of dicarboxylic acids in n-alkane-amended cultures indicated the biotransformation of paraffin to methane under anoxic condition. 16S rRNA gene analysis suggested that the dominant methanogen in n-alkane-degrading cultures shifted from Methanothermobacter on day 322 to Thermoplasmatales on day 736. Bacterial community analysis based on high-throughput sequencing revealed that members of Proteobacteria and Firmicutes exhibiting predominant in control cultures, while microorganisms affiliated with Actinobacteria turned into the most dominant phylum in n-alkane-dependent cultures. Additionally, the relative abundance of mcrA gene based on genomic DNA significantly increased over the incubation time, suggesting an important role of methanogens in these consortia. This work extends our understanding of methanogenic paraffinic n-alkanes conversion and has biotechnological implications for microbial enhanced recovery of residual hydrocarbons and effective bioremediation of hydrocarbon-containing biospheres.
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20
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Küppers J, Mitschke N, Heyen S, Rabus R, Wilkes H, Christoffers J. Metabolites of the Anaerobic Degradation of n-Hexane by Denitrifying Betaproteobacterium Strain HxN1. Chembiochem 2020; 21:373-380. [PMID: 31294892 PMCID: PMC7028053 DOI: 10.1002/cbic.201900375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Indexed: 11/05/2022]
Abstract
The constitutions of seven metabolites formed during anaerobic degradation of n-hexane by the denitrifying betaproteobacterium strain HxN1 were elucidated by comparison of their GC and MS data with those of synthetic reference standards. The synthesis of 4-methyloctanoic acid derivatives was accomplished by the conversion of 2-methylhexanoyl chloride with Meldrum's acid. The β-oxoester was reduced with NaBH4 , the hydroxy group was eliminated, and the double bond was displaced to yield the methyl esters of 4-methyl-3-oxooctanoate, 3-hydroxy-4-methyloctanoate, (E)-4-methyl-2-octenoate, and (E)- and (Z)-4-methyl-3-octenoate. The methyl esters of 2-methyl-3-oxohexanoate and 3-hydroxy-2-methylhexanoate were similarly prepared from butanoyl chloride and Meldrum's acid. However, methyl (E)-2-methyl-2-hexenoate was prepared by Horner-Wadsworth-Emmons reaction, followed by isomerization to methyl (E)-2-methyl-3-hexenoate. This investigation, with the exception of 4-methyl-3-oxooctanoate, which was not detectable in the cultures, completes the unambiguous identification of all intermediates of the anaerobic biodegradation of n-hexane to 2-methyl-3-oxohexanoyl coenzyme A (CoA), which is then thiolytically cleaved to butanoyl-CoA and propionyl-CoA; these two metabolites are further transformed according to established pathways.
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Affiliation(s)
- Julian Küppers
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Nico Mitschke
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Simone Heyen
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Ralf Rabus
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
| | - Jens Christoffers
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, 26111, Oldenburg, Germany
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21
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Ji JH, Zhou L, Mbadinga SM, Irfan M, Liu YF, Pan P, Qi ZZ, Chen J, Liu JF, Yang SZ, Gu JD, Mu BZ. Methanogenic biodegradation of C 9 to C 12n-alkanes initiated by Smithella via fumarate addition mechanism. AMB Express 2020; 10:23. [PMID: 32008120 PMCID: PMC6995468 DOI: 10.1186/s13568-020-0956-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/16/2020] [Indexed: 11/15/2022] Open
Abstract
In the present study, a methanogenic alkane-degrading (a mixture of C9 to C12n-alkanes) culture enriched from production water of a low-temperature oil reservoir was established and assessed. Significant methane production was detected in the alkane-amended enrichment cultures compared with alkane-free controls over an incubation period of 1 year. At the end of the incubation, fumarate addition metabolites (C9 to C12 alkylsuccinates) and assA genes (encoding the alpha subunit of alkylsuccinate synthase) were detected only in the alkane-amended enrichment cultures. Microbial community analysis showed that putative syntrophic n-alkane degraders (Smithella) capable of initiating n-alkanes by fumarate addition mechanism were enriched in the alkane-amended enrichment cultures. In addition, both hydrogenotrophic (Methanocalculus) and acetoclastic (Methanothrix) methanogens were also observed. Our results provide further evidence that alkanes can be activated by addition to fumarate under methanogenic conditions.
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22
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Mitschke N, Jarling R, Rabus R, Christoffers J, Wilkes H. Metabolites of the anaerobic degradation of diethyl ether by denitrifying betaproteobacterium strain HxN1. Org Biomol Chem 2020; 18:7098-7109. [DOI: 10.1039/d0ob01419b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The constitutions of five metabolites formed during anaerobic degradation of diethyl ether by the denitrifying bacterium Aromatoleum sp. HxN1 were identified by comparison with synthesized standards using GC-MS.
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Affiliation(s)
- Nico Mitschke
- Institut für Chemie und Biologie des Meeres (ICBM)
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg
- Germany
| | - René Jarling
- Institut für Chemie und Biologie des Meeres (ICBM)
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg
- Germany
| | - Ralf Rabus
- Institut für Chemie und Biologie des Meeres (ICBM)
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg
- Germany
| | - Jens Christoffers
- Institut für Chemie
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg
- Germany
| | - Heinz Wilkes
- Institut für Chemie und Biologie des Meeres (ICBM)
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg
- Germany
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23
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Methanogenic Degradation of Long n-Alkanes Requires Fumarate-Dependent Activation. Appl Environ Microbiol 2019; 85:AEM.00985-19. [PMID: 31175186 DOI: 10.1128/aem.00985-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 05/29/2019] [Indexed: 11/20/2022] Open
Abstract
Methanogenic degradation of n-alkanes is prevalent in n-alkane-impacted anoxic oil reservoirs and oil-polluted sites. However, little is known about the initial activation mechanism of the substrate, especially n-alkanes with a chain length above C16 Here, a methanogenic C16 to C20 n-alkane-degrading enrichment culture was established from production water of a low-temperature oil reservoir. At the end of the incubation (364 days), C16 to C20 (1-methylalkyl)succinates were detected in the n-alkane-amended enrichment culture, suggesting that fumarate addition had occurred in the degradation process. This evidence is supported further by the positive amplification of the assA gene encoding the alpha subunit of alkylsuccinate synthase. A phylogenetic analysis shows these assA amplicons to be affiliated with Smithella and Desulfatibacillum clades. Together with the high abundance of these clades in the bacterial community, these two species are postulated to be the key players in the degradation of C16 to C20 n-alkanes in the present study. Our results provide evidence that long n-alkanes are activated via a fumarate addition mechanism under methanogenic conditions.IMPORTANCE Methanogenic hydrocarbon degradation is the major process for oil degradation in subsurface oil reservoirs and is blamed for the formation of heavy oil and oil sands. Addition of n-alkanes to fumarate yielding alkyl-substituted succinates is a well-characterized anaerobic activation mechanism for hydrocarbons and is the most common activation mechanism in the anaerobic biodegradation of n-alkanes with chain lengths less than C16 However, the activation mechanism involved in the methanogenic biodegradation of n-alkanes longer than C16 is still uncertain. In this study, we analyzed a methanogenic enrichment culture amended with a mixture of C16 to C20 n-alkanes. These n-alkanes can be activated via fumarate addition by mixed cultures containing Smithella and Desulfatibacillum species under methanogenic conditions. These observations provide a fundamental understanding of long-n-alkane metabolism under methanogenic conditions and have important applications for the remediation of oil-contaminated sites and for energy recovery from oil reservoirs.
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Chen L, Hu Q, Zhang X, Chen Z, Wang Y, Liu S. Effects of salinity on the biological performance of anaerobic membrane bioreactor. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 238:263-273. [PMID: 30852403 DOI: 10.1016/j.jenvman.2019.03.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/31/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
The performance of anaerobic membrane bioreactor (AnMBR) was evaluated treating synthetic wastewater with various concentrations of NaCl (0-40 g/L), as well as the recovery phase. The effluent COD removal efficiency decreased from 96.4% to 95.0%, 91.4%, 86.7% and 77.7% with stepwise increasing of salt concentration from 0 to 5, 10, 20 and 40 g NaCl/L, respectively, then gradually increased to 94.1% during the recovery phase. Additionally, the significant changes in the content and composition of soluble microbial products (SMP) and extracellular polymer substance (EPS) were obtained under higher salt stress. GC-MS analyses were carried out for the effluent, and some new types of compounds, such as Dodecane, Undecane, and Ethyl Acetate, were found during salt exposure phases. The characterization of the microbial community was also investigated based on the analysis of genomic 16S rDNA, revealing the increasing salinity (5-40 g NaCl/L) could reduce the diversity of sludge microbial community in AnMBR. Meanwhile, the significant effects on the composition of dominate phyla (Proteobacteria, Bacteroidetes, Firmicutes and Chloroflexi) were found during the salt exposure phase.
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Affiliation(s)
- Lin Chen
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China.
| | - Qinzheng Hu
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
| | - Xin Zhang
- School of Engineering, RMIT University, Melbourne, 3000, Australia
| | - Zaiyu Chen
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
| | - Yuchen Wang
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
| | - Shanshan Liu
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
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25
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Chen L, Hu Q, Zhang X, Cai Z, Wang Y. Effects of ZnO nanoparticles on the performance of anaerobic membrane bioreactor: An attention to the characteristics of supernatant, effluent and biomass community. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 248:743-755. [PMID: 30851584 DOI: 10.1016/j.envpol.2019.02.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/24/2019] [Accepted: 02/17/2019] [Indexed: 06/09/2023]
Abstract
Two laboratory-scale anaerobic membrane bioreactor (AnMBRs) were built to investigate the effect of zinc oxide nanoparticles (ZnO-NPs) on their performance, and the recovery phase was also examined. Results showed that the addition of ZnO-NPs with 0.4 mg/L caused significant deteriorations of AnMBR performance, including decrements of chemical oxygen demand (COD) removal efficiency from 96.4% to 81.5% and biogas production from 0.36 to 0 L/g COD removal within 40 days. A significant increment from 13.2 to 52.1 mg/L in soluble microbial products (SMP) was obtained, while no obvious effect on colloids was observed except an increased fluctuation of colloid concentration. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis revealed remarkable changes of compounds in effluent with exposure to ZnO-NPs, and some new alkanes and esters were produced, such as Cyclobutane, 1,2-diethyl-, trans-, Tetradecane, Cyclopropane, octyl-, and Butanoic acid, methyl ester. The microbial community was compared using high-throughput sequencing, clearly showing the changes in both bacteria and archaea communities. Furthermore, results for recovery phase indicated that the AnMBR performance can be recovered within around 60 days after stopping ZnO-NPs addition, accompanied by the decrement of zinc concentration mainly adsorbed by sludge.
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Affiliation(s)
- Lin Chen
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China.
| | - Qinzheng Hu
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
| | - Xin Zhang
- School of Engineering, RMIT University, Melbourne, 3000, Australia
| | - Zongting Cai
- Engineering Sciences, University College London, London, WC1E 6BT, UK
| | - Yue Wang
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes, Hohai University, Nanjing, 210098, China; College of Environment, Hohai University, Nanjing, 210098, China
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26
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Methanogenic degradation of branched alkanes in enrichment cultures of production water from a high-temperature petroleum reservoir. Appl Microbiol Biotechnol 2019; 103:2391-2401. [DOI: 10.1007/s00253-018-09574-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/10/2018] [Accepted: 12/10/2018] [Indexed: 11/26/2022]
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27
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Zhu H, Han Y, Xu C, Han H, Ma W. Overview of the state of the art of processes and technical bottlenecks for coal gasification wastewater treatment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 637-638:1108-1126. [PMID: 29801205 DOI: 10.1016/j.scitotenv.2018.05.054] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/04/2018] [Accepted: 05/04/2018] [Indexed: 06/08/2023]
Abstract
CGWW is major waste stream resulting from a number of activities of the low/medium temperature gasification unit that occurs during the production of natural gas. The resulting effluent contains a broad spectrum of organic and inorganic contaminants and exerts a negative influence on the environment, mainly due to the presence of toxic and refractory compounds. So far, various technologies have been applied for treatment of CGWW, while few reviews are available in the literature. Thus, this review attempts to offer a comprehensive picture about CGWW. An overview about pretreatment, biological and advanced processes for treatment of CGWW is presented, and the degradation mechanism of toxic and refractory pollutants is also elaborated. Technical bottlenecks existing in the operation of coal chemical industries, including foam proliferation, odors and biotoxicity risk, are detailed analyzed. Finally, the prospects of treatment for CGWW are discussed based on the concept of "wastewater is money". The review can be provided as an effective technical support for the construction and operation of coal gasification industries.
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Affiliation(s)
- Hao Zhu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yuxing Han
- School of Engineering, South China Agriculture University, Guangzhou 510642, China
| | - Chunyan Xu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Hongjun Han
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Weiwei Ma
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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28
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Affiliation(s)
- Christof M. Jäger
- University of Nottingham; Department of Chemical and Environmental Engineering; NG7 2RD Nottingham United Kingdom
| | - Anna K. Croft
- University of Nottingham; Department of Chemical and Environmental Engineering; NG7 2RD Nottingham United Kingdom
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29
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Toth CRA, Gieg LM. Time Course-Dependent Methanogenic Crude Oil Biodegradation: Dynamics of Fumarate Addition Metabolites, Biodegradative Genes, and Microbial Community Composition. Front Microbiol 2018; 8:2610. [PMID: 29354103 PMCID: PMC5758579 DOI: 10.3389/fmicb.2017.02610] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/14/2017] [Indexed: 11/13/2022] Open
Abstract
Biodegradation of crude oil in subsurface petroleum reservoirs has adversely impacted most of the world's oil, converting this resource to heavier forms that are of lower quality and more challenging to recover. Oil degradation in deep reservoir environments has been attributed to methanogenesis over geological time, yet our understanding of the processes and organisms mediating oil transformation in the absence of electron acceptors remains incomplete. Here, we sought to identify hydrocarbon activation mechanisms and reservoir-associated microorganisms that may have helped shape the formation of biodegraded oil by incubating oilfield produced water in the presence of light (°API = 32) or heavy crude oil (°API = 16). Over the course of 17 months, we conducted routine analytical (GC, GC-MS) and molecular (PCR/qPCR of assA and bssA genes, 16S rRNA gene sequencing) surveys to assess microbial community composition and activity changes over time. Over the incubation period, we detected the formation of transient hydrocarbon metabolites indicative of alkane and alkylbenzene addition to fumarate, corresponding with increases in methane production and fumarate addition gene abundance. Chemical and gene-based evidence of hydrocarbon biodegradation under methanogenic conditions was supported by the enrichment of hydrocarbon fermenters known to catalyze fumarate addition reactions (e.g., Desulfotomaculum, Smithella), along with syntrophic bacteria (Syntrophus), methanogenic archaea, and several candidate phyla (e.g., “Atribacteria”, “Cloacimonetes”). Our results reveal that fumarate addition is a possible mechanism for catalyzing the methanogenic biodegradation of susceptible saturates and aromatic hydrocarbons in crude oil, and we propose the roles of community members and candidate phyla in our cultures that may be involved in hydrocarbon transformation to methane in crude oil systems.
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Affiliation(s)
- Courtney R A Toth
- Petroleum Microbiology Research Group, Department of Biological Sciences, 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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30
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Oberding LK, Gieg LM. Methanogenic Paraffin Biodegradation: Alkylsuccinate Synthase Gene Quantification and Dicarboxylic Acid Production. Appl Environ Microbiol 2018; 84:e01773-17. [PMID: 29030441 PMCID: PMC5734044 DOI: 10.1128/aem.01773-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/09/2017] [Indexed: 11/20/2022] Open
Abstract
Paraffinic n-alkanes (>C17) that are solid at ambient temperature comprise a large fraction of many crude oils. The comparatively low water solubility and reactivity of these long-chain alkanes can lead to their persistence in the environment following fuel spills and pose serious problems for crude oil recovery operations by clogging oil production wells. However, the degradation of waxy paraffins under the anoxic conditions characterizing contaminated groundwater environments and deep subsurface energy reservoirs is poorly understood. Here, we assessed the ability of a methanogenic culture enriched from freshwater fuel-contaminated aquifer sediments to biodegrade the model paraffin n-octacosane (C28H58). Compared with that in controls, the consumption of n-octacosane was coupled to methane production, demonstrating its biodegradation under these conditions. Smithella was postulated to be an important C28H58 degrader in the culture on the basis of its high relative abundance as determined by 16S rRNA gene sequencing. An identified assA gene (known to encode the α subunit of alkylsuccinate synthase) aligned most closely with those from other Smithella organisms. Quantitative PCR (qPCR) and reverse transcription qPCR assays for assA demonstrated significant increases in the abundance and expression of this gene in C28H58-degrading cultures compared with that in controls, suggesting n-octacosane activation by fumarate addition. A metabolite analysis revealed the presence of several long-chain α,ω-dicarboxylic acids only in the C28H58-degrading cultures, a novel observation providing clues as to how methanogenic consortia access waxy hydrocarbons. The results of this study broaden our understanding of how waxy paraffins can be biodegraded in anoxic environments with an application toward bioremediation and improved oil recovery.IMPORTANCE Understanding the methanogenic biodegradation of different classes of hydrocarbons has important applications for effective fuel-contaminated site remediation and for improved recovery from oil reservoirs. Previous studies have clearly demonstrated that short-chain alkanes (C17) that comprise many fuel mixtures. Using an enrichment culture derived from a freshwater fuel-contaminated site, we demonstrate that the model waxy alkane n-octacosane can be biodegraded under methanogenic conditions by a presumed Smithella phylotype. Compared with that of controls, we show an increased abundance and expression of the assA gene, which is known to be important for anaerobic n-alkane metabolism. Metabolite analyses revealed the presence of a range of α,ω-dicarboxylic acids found only in n-octacosane-degrading cultures, a novel finding that lends insight as to how anaerobic communities may access waxes as growth substrates in anoxic environments.
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Affiliation(s)
- Lisa K Oberding
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Lisa M Gieg
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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31
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Singh R, Guzman MS, Bose A. Anaerobic Oxidation of Ethane, Propane, and Butane by Marine Microbes: A Mini Review. Front Microbiol 2017; 8:2056. [PMID: 29109712 PMCID: PMC5660070 DOI: 10.3389/fmicb.2017.02056] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/06/2017] [Indexed: 12/16/2022] Open
Abstract
The deep ocean and its sediments are a continuous source of non-methane short-chain alkanes (SCAs) including ethane, propane, and butane. Their high global warming potential, and contribution to local carbon and sulfur budgets has drawn significant scientific attention. Importantly, microbes can use gaseous alkanes and oxidize them to CO2, thus acting as effective biofilters. A relative decrease of these gases with a concomitant 13C enrichment of propane and n-butane in interstitial waters vs. the source suggests microbial anaerobic oxidation. The reported uncoupling of sulfate-reduction (SR) from anaerobic methane oxidation supports their microbial consumption. To date, strain BuS5 isolated from the sediments of Guaymas Basin, Gulf of California, is the only pure culture that can anaerobically degrade propane and n-butane. This organism belongs to a metabolically diverse cluster within the Deltaproteobacteria called Desulfosarcina/Desulfococcus. Other phylotypes involved in gaseous alkane degradation were identified based on stable-isotope labeling and fluorescence in-situ hybridization. A novel syntrophic association of the archaeal genus, Candidatus Syntrophoarchaeum, and a thermophilic SR bacterium, HotSeep-1 was recently discovered from the Guaymas basin, Gulf of California that can anaerobically oxidize n-butane. Strikingly, metagenomic data and the draft genomes of ca. Syntrophoarchaeum suggest that this organism uses a novel mechanism for n-butane oxidation, distinct from the well-established fumarate addition mechanism. These recent findings indicate that a lot remains to be understood about our understanding of anaerobic SCA degradation. This mini-review summarizes our current understanding of microbial anaerobic SCA degradation, and provides an outlook for future research.
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Affiliation(s)
- Rajesh Singh
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Michael S Guzman
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
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32
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Backman LRF, Funk MA, Dawson CD, Drennan CL. New tricks for the glycyl radical enzyme family. Crit Rev Biochem Mol Biol 2017; 52:674-695. [PMID: 28901199 DOI: 10.1080/10409238.2017.1373741] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Glycyl radical enzymes (GREs) are important biological catalysts in both strict and facultative anaerobes, playing key roles both in the human microbiota and in the environment. GREs contain a backbone glycyl radical that is post-translationally installed, enabling radical-based mechanisms. GREs function in several metabolic pathways including mixed acid fermentation, ribonucleotide reduction and the anaerobic breakdown of the nutrient choline and the pollutant toluene. By generating a substrate-based radical species within the active site, GREs enable C-C, C-O and C-N bond breaking and formation steps that are otherwise challenging for nonradical enzymes. Identification of previously unknown family members from genomic data and the determination of structures of well-characterized GREs have expanded the scope of GRE-catalyzed reactions as well as defined key features that enable radical catalysis. Here, we review the structures and mechanisms of characterized GREs, classifying members into five categories. We consider the open questions about each of the five GRE classes and evaluate the tools available to interrogate uncharacterized GREs.
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Affiliation(s)
- Lindsey R F Backman
- a Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Michael A Funk
- a Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA , USA.,b Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , IL , USA
| | - Christopher D Dawson
- c Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Catherine L Drennan
- a Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA , USA.,c Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA.,d Howard Hughes Medical Institute , Massachusetts Institute of Technology , Cambridge , MA , USA
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33
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Protein Stability and Unfolding Following Glycine Radical Formation. Molecules 2017; 22:molecules22040655. [PMID: 28422069 PMCID: PMC6154654 DOI: 10.3390/molecules22040655] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 04/12/2017] [Accepted: 04/13/2017] [Indexed: 02/02/2023] Open
Abstract
Glycine (Gly) residues are particularly susceptible to hydrogen abstraction; which results in the formation of the capto-dative stabilized Cα-centered Gly radical (GLR) on the protein backbone. We examined the effect of GLR formation on the structure of the Trp cage; tryptophan zipper; and the villin headpiece; three fast-folding and stable miniproteins; using all-atom (OPLS-AA) molecular dynamics simulations. Radicalization changes the conformation of the GLR residue and affects both neighboring residues but did not affect the stability of the Trp zipper. The stability of helices away from the radical center in villin were also affected by radicalization; and GLR in place of Gly15 caused the Trp cage to unfold within 1 µs. These results provide new evidence on the destabilizing effects of protein oxidation by reactive oxygen species.
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34
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Laso-Pérez R, Wegener G, Knittel K, Widdel F, Harding KJ, Krukenberg V, Meier DV, Richter M, Tegetmeyer HE, Riedel D, Richnow HH, Adrian L, Reemtsma T, Lechtenfeld OJ, Musat F. Thermophilic archaea activate butane via alkyl-coenzyme M formation. Nature 2016; 539:396-401. [PMID: 27749816 DOI: 10.1038/nature20152] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/11/2016] [Indexed: 12/25/2022]
Abstract
The anaerobic formation and oxidation of methane involve unique enzymatic mechanisms and cofactors, all of which are believed to be specific for C1-compounds. Here we show that an anaerobic thermophilic enrichment culture composed of dense consortia of archaea and bacteria apparently uses partly similar pathways to oxidize the C4 hydrocarbon butane. The archaea, proposed genus 'Candidatus Syntrophoarchaeum', show the characteristic autofluorescence of methanogens, and contain highly expressed genes encoding enzymes similar to methyl-coenzyme M reductase. We detect butyl-coenzyme M, indicating archaeal butane activation analogous to the first step in anaerobic methane oxidation. In addition, Ca. Syntrophoarchaeum expresses the genes encoding β-oxidation enzymes, carbon monoxide dehydrogenase and reversible C1 methanogenesis enzymes. This allows for the complete oxidation of butane. Reducing equivalents are seemingly channelled to HotSeep-1, a thermophilic sulfate-reducing partner bacterium known from the anaerobic oxidation of methane. Genes encoding 16S rRNA and methyl-coenzyme M reductase similar to those identifying Ca. Syntrophoarchaeum were repeatedly retrieved from marine subsurface sediments, suggesting that the presented activation mechanism is naturally widespread in the anaerobic oxidation of short-chain hydrocarbons.
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Affiliation(s)
- Rafael Laso-Pérez
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany.,Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Gunter Wegener
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany.,Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.,MARUM, Center for Marine Environmental Sciences, University Bremen, 28359 Bremen, Germany
| | - Katrin Knittel
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Friedrich Widdel
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Katie J Harding
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Viola Krukenberg
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany.,Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Dimitri V Meier
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Michael Richter
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Halina E Tegetmeyer
- Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.,Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Dietmar Riedel
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | | | - Lorenz Adrian
- Helmholtz Centre for Environmental Research - UFZ, 04318 Leipzig, Germany
| | - Thorsten Reemtsma
- Helmholtz Centre for Environmental Research - UFZ, 04318 Leipzig, Germany
| | | | - Florin Musat
- Max-Planck Institute for Marine Microbiology, 28359 Bremen, Germany.,Helmholtz Centre for Environmental Research - UFZ, 04318 Leipzig, Germany
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35
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Seyhan D, Friedrich P, Szaleniec M, Hilberg M, Buckel W, Golding BT, Heider J. Stereochemischer Verlauf der enzymatischen Synthese von Benzylsuccinat mit chiral markiertem Toluol. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201605197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Deniz Seyhan
- Laboratorium für Mikrobielle Biochemie und Synmikro-Zentrum für synthetische Mikrobiologie; Philipps Universität Marburg; 35043 Marburg an der Lahn Deutschland
| | - Peter Friedrich
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU Großbritannien
| | - Maciej Szaleniec
- Jerzy Haber Institute of Catalysis and Surface Chemistry; Polish Academy of Science; 30-239 Krakau Polen
| | - Markus Hilberg
- Laboratorium für Mikrobielle Biochemie und Synmikro-Zentrum für synthetische Mikrobiologie; Philipps Universität Marburg; 35043 Marburg an der Lahn Deutschland
| | - Wolfgang Buckel
- Max-Planck-Institut für terrestrische Mikrobiologie; 35043 Marburg an der Lahn Deutschland
| | - Bernard T. Golding
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU Großbritannien
| | - Johann Heider
- Laboratorium für Mikrobielle Biochemie und Synmikro-Zentrum für synthetische Mikrobiologie; Philipps Universität Marburg; 35043 Marburg an der Lahn Deutschland
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36
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Seyhan D, Friedrich P, Szaleniec M, Hilberg M, Buckel W, Golding BT, Heider J. Elucidating the Stereochemistry of Enzymatic Benzylsuccinate Synthesis with Chirally Labeled Toluene. Angew Chem Int Ed Engl 2016; 55:11664-7. [PMID: 27503670 DOI: 10.1002/anie.201605197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/01/2016] [Indexed: 11/08/2022]
Abstract
Benzylsuccinate synthase is a glycyl radical enzyme that initiates anaerobic toluene metabolism by adding fumarate to the methyl group of toluene to yield (R)-benzylsuccinate. To investigate whether the reaction occurs with retention or inversion of configuration at the methyl group of toluene, we synthesized both enantiomers of chiral toluene with all three H isotopes in their methyl groups. The chiral toluenes were converted into benzylsuccinates preferentially containing (2) H and (3) H at their benzylic C atoms, owing to a kinetic isotope effect favoring hydrogen abstraction from the methyl groups. The configuration of the products was analyzed by enzymatic CoA-thioester synthesis and stereospecific oxidation using enzymes involved in benzylsuccinate degradation. Assessment of the configurations of the benzylsuccinate isomers based on loss or retention of tritium showed that inversion of configuration at the methyl group occurs when the chiral toluenes react with fumarate.
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Affiliation(s)
- Deniz Seyhan
- Laboratorium für Mikrobielle Biochemie and Synmikro-Zentrum für synthetische Mikrobiologie, Philipps Universität Marburg, 35043, Marburg an der Lahn, Germany
| | - Peter Friedrich
- School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Maciej Szaleniec
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Science, 30-239, Kraków, Poland
| | - Markus Hilberg
- Laboratorium für Mikrobielle Biochemie and Synmikro-Zentrum für synthetische Mikrobiologie, Philipps Universität Marburg, 35043, Marburg an der Lahn, Germany
| | - Wolfgang Buckel
- Max-Planck-Institut für terrestrische Mikrobiologie, 35043, Marburg an der Lahn, Germany
| | - Bernard T Golding
- School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Johann Heider
- Laboratorium für Mikrobielle Biochemie and Synmikro-Zentrum für synthetische Mikrobiologie, Philipps Universität Marburg, 35043, Marburg an der Lahn, Germany.
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37
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Kern M, Watzinger A, Scherr KE. 15N-nitrate and 34S-sulfate isotopic fractionation reflects electron acceptor 'recycling' during hydrocarbon biodegradation. N Biotechnol 2016; 38:91-100. [PMID: 27079862 DOI: 10.1016/j.nbt.2016.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 03/09/2016] [Accepted: 03/16/2016] [Indexed: 11/19/2022]
Abstract
The analysis of stable carbon isotopes for the assessment of contaminant fate in the aquifer is impeded in the case of petroleum hydrocarbons (TPH) by their chain length. Alternatively, the coupled nitrogen-sulfur-carbon cycles involved into TPH biodegradation under sulfate- and nitrate reducing conditions can be investigated using nitrogen (δ15N) and sulfur (δ34S) isotopic shifts in terminal electron acceptors (TEA) involved in anaerobic TPH oxidation. Biodegradation of a paraffin-rich crude oil was studied in anaerobic aquifer microcosms with nitrate (NIT), sulfate (SUL), nitrate plus sulfate (MIX) and nitrate under sulfate reduction suppression by molybdate (MOL) as TEA. After 8 months, TPH biodegradation was not different (around 33%) in experiments receiving only nitrate (NIT, MOL) versus under mixed TEA-conditions (MIX), despite higher biodiversity under mixed conditions (H'NIT and H'MOL≈5.9, H'MIX=8.0). Molybdate addition effected higher nitrate depletion, possibly by increasing the production of nitrate reductase. Additional sulfate depletion under mixed conditions suggested bioconversion of polar intermediates. Microcosms only receiving sulfate (SUL) showed no significant TEA and TPH decrease. A Rayleigh kinetic isotope enrichment model for isotopic 15N/14N and 34S/32S shifts in residual TEA gave apparent enrichment factors ɛN,NIT and ɛN,MOL values of -16.7 to -18.0‰ for nitrate as sole TEA and ɛN,MIX of -6.0‰ and ɛS,MIX of -4.1‰ under mixed electron accepting conditions. The low isotopic fractionation under mixed terminal electron accepting conditions was attributed to lithotrophic, sulfide-dependent denitrification by Thiobacillus species, while it was hypothesized that Desulfovibrio replenished the reduced sulfur pool via oxidation of polar hydrocarbon metabolites. Concurrently, organotrophic denitrification was performed by Pseudomonas species, with isotopic fractionation expressed by ɛN,MIX representing the superposition of both denitrification processes. This is, to our knowledge, the first characterization of sulfur and nitrogen isotopic shifts associated to concurrent organotrophic and lithotrophic denitrification in a hydrocarbon-contaminated environment, and offers the prospect of improved understanding of biogeochemical cycles including in situ hydrocarbon biotransformation.
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Affiliation(s)
- Martin Kern
- University of Natural Resources and Life Sciences (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln, Austria
| | - Andrea Watzinger
- AIT Austrian Institute of Technology GmbH, Energy Department, Environmental Resources and Technologies, Konrad Lorenz Straße 24, 3430 Tulln, Austria
| | - Kerstin E Scherr
- University of Natural Resources and Life Sciences (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln, Austria.
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Herath A, Wawrik B, Qin Y, Zhou J, Callaghan AV. Transcriptional response of Desulfatibacillum alkenivorans AK-01 to growth on alkanes: insights from RT-qPCR and microarray analyses. FEMS Microbiol Ecol 2016; 92:fiw062. [PMID: 27009900 DOI: 10.1093/femsec/fiw062] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2016] [Indexed: 12/16/2022] Open
Abstract
Microbial transformation of n-alkanes in anaerobic ecosystems plays a pivotal role in biogeochemical carbon cycling and bioremediation, but the requisite genetic machinery is not well elucidated.Desulfatibacillum alkenivorans AK-01 utilizes n-alkanes (C13 to C18) and contains two genomic loci encoding alkylsuccinate synthase (ASS) gene clusters. ASS catalyzes alkane addition to fumarate to form methylalkylsuccinic acids. We hypothesized that the genes in the two clusters would be differentially expressed depending on the alkane substrate utilized for growth. RT-qPCR was used to investigate ass-gene expression across AK-01's known substrate range, and microarray-based transcriptomic analysis served to investigate whole-cell responses to growth on n-hexadecane versus hexadecanoate. RT-qPCR revealed induction of ass gene cluster 1 during growth on all tested alkane substrates, and the transcriptional start sites in cluster 1 were determined via 5'RACE. Induction of ass gene cluster 2 was not observed under the tested conditions. Transcriptomic analysis indicated that the upregulation of genes potentially involved in methylalkylsuccinate metabolism, including methylmalonyl-CoA mutase and a putative carboxyl transferase. These findings provide new directions for studying the transcriptional regulation of genes involved in alkane addition to fumarate, fumarate recycling and the processing of methylalkylsuccinates with regard to isolates, enrichment cultures and ecological datasets.
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Affiliation(s)
- Anjumala Herath
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Boris Wawrik
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Yujia Qin
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA Institute of Environmental Genomics, Stephenson Research Center, 101 David L. Boren Blvd, Norman, OK 73019, USA
| | - Jizhong Zhou
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA Institute of Environmental Genomics, Stephenson Research Center, 101 David L. Boren Blvd, Norman, OK 73019, USA Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94270, USA State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Amy V Callaghan
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
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Vogt C, Lueders T, Richnow HH, Krüger M, von Bergen M, Seifert J. Stable Isotope Probing Approaches to Study Anaerobic Hydrocarbon Degradation and Degraders. J Mol Microbiol Biotechnol 2016; 26:195-210. [DOI: 10.1159/000440806] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Stable isotope probing (SIP) techniques have become state-of-the-art in microbial ecology over the last 10 years, allowing for the targeted detection and identification of organisms, metabolic pathways and elemental fluxes active in specific processes within complex microbial communities. For studying anaerobic hydrocarbon-degrading microbial communities, four stable isotope techniques have been used so far: DNA/RNA-SIP, PLFA (phospholipid-derived fatty acids)-SIP, protein-SIP, and single-cell-SIP by nanoSIMS (nanoscale secondary ion mass spectrometry) or confocal Raman microscopy. DNA/RNA-SIP techniques are most frequently applied due to their most meaningful phylogenetic resolution. Especially using <sup>13</sup>C-labeled benzene and toluene as model substrates, many new hydrocarbon degraders have been identified by SIP under various electron acceptor conditions. This has extended the current perspective of the true diversity of anaerobic hydrocarbon degraders relevant in the environment. Syntrophic hydrocarbon degradation was found to be a common mechanism for various electron acceptors. Fundamental concepts and recent advances in SIP are reflected here. A discussion is presented concerning how these techniques generate direct insights into intrinsic hydrocarbon degrader populations in environmental systems and how useful they are for more integrated approaches in the monitoring of contaminated sites and for bioremediation.
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40
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Musat F, Vogt C, Richnow HH. Carbon and Hydrogen Stable Isotope Fractionation Associated with the Aerobic and Anaerobic Degradation of Saturated and Alkylated Aromatic Hydrocarbons. J Mol Microbiol Biotechnol 2016; 26:211-26. [DOI: 10.1159/000442161] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Saturated hydrocarbons (alkanes) and alkylated aromatic hydrocarbons are abundant environmental compounds. Hydrocarbons are primarily removed from the environment by biodegradation, a process usually associated with moderate carbon and significant hydrogen isotope fractionation allowing monitoring of biodegradation processes in the environment. Here, we review the carbon and hydrogen stable isotope fractionation associated with the cleavage of C-H bonds at alkyl chains of hydrocarbons. Propane, <i>n</i>-butane and ethylbenzene were used as model components for alkyl moieties of aliphatic and aromatic hydrocarbons with emphasis on the cleavage of the C-H bond without the involvement of molecular oxygen. The carbon and hydrogen isotope fractionation factors were further used to explore the diagnostic potential for characterizing the mode of bond cleavage under oxic and anoxic conditions. Λ factors, calculated to correlate carbon and hydrogen fractionation, allowed to distinguish between aerobic and anaerobic biodegradation processes in the environment.
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von Netzer F, Kuntze K, Vogt C, Richnow HH, Boll M, Lueders T. Functional Gene Markers for Fumarate-Adding and Dearomatizing Key Enzymes in Anaerobic Aromatic Hydrocarbon Degradation in Terrestrial Environments. J Mol Microbiol Biotechnol 2016; 26:180-94. [PMID: 26959523 DOI: 10.1159/000441946] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Anaerobic degradation is a key process in many environments either naturally or anthropogenically exposed to petroleum hydrocarbons. Considerable advances into the biochemistry and physiology of selected anaerobic degraders have been achieved over the last decades, especially for the degradation of aromatic hydrocarbons. However, researchers have only recently begun to explore the ecology of complex anaerobic hydrocarbon degrader communities directly in their natural habitats, as well as in complex laboratory systems using tools of molecular biology. These approaches have mainly been facilitated by the establishment of a suite of targeted marker gene assays, allowing for rapid and directed insights into the diversity as well as the identity of intrinsic degrader populations and degradation potentials established at hydrocarbon-impacted sites. These are based on genes encoding either peripheral or central key enzymes in aromatic compound breakdown, such as fumarate-adding benzylsuccinate synthases or dearomatizing aryl-coenzyme A reductases, or on aromatic ring-cleaving hydrolases. Here, we review recent advances in this field, explain the different detection methodologies applied, and discuss how the detection of site-specific catabolic gene markers has improved the understanding of processes at contaminated sites. Functional marker gene-based strategies may be vital for the development of a more elaborate population-based assessment and prediction of aromatic degradation potentials in hydrocarbon-impacted environments.
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Affiliation(s)
- Frederick von Netzer
- Helmholtz Zentrum Mx00FC;nchen - German Research Center for Environmental Health, Institute of Groundwater Ecology, Neuherberg, Germany
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Heider J, Szaleniec M, Sünwoldt K, Boll M. Ethylbenzene Dehydrogenase and Related Molybdenum Enzymes Involved in Oxygen-Independent Alkyl Chain Hydroxylation. J Mol Microbiol Biotechnol 2016; 26:45-62. [PMID: 26960184 DOI: 10.1159/000441357] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ethylbenzene dehydrogenase initiates the anaerobic bacterial degradation of ethylbenzene and propylbenzene. Although the enzyme is currently only known from a few closely related denitrifying bacterial strains affiliated to the Rhodocyclaceae, it clearly marks a universally occurring mechanism used for attacking recalcitrant substrates in the absence of oxygen. Ethylbenzene dehydrogenase belongs to subfamily 2 of the DMSO reductase-type molybdenum enzymes together with paralogous enzymes involved in the oxygen-independent hydroxylation of p-cymene, the isoprenoid side chains of sterols and even possibly n-alkanes; the subfamily also extends to dimethylsulfide dehydrogenases, selenite, chlorate and perchlorate reductases and, most significantly, dissimilatory nitrate reductases. The biochemical, spectroscopic and structural properties of the oxygen-independent hydroxylases among these enzymes are summarized and compared. All of them consist of three subunits, contain a molybdenum-bis-molybdopterin guanine dinucleotide cofactor, five Fe-S clusters and a heme b cofactor of unusual ligation, and are localized in the periplasmic space as soluble enzymes. In the case of ethylbenzene dehydrogenase, it has been determined that the heme b cofactor has a rather high redox potential, which may also be inferred for the paralogous hydroxylases. The known structure of ethylbenzene dehydrogenase allowed the calculation of detailed models of the reaction mechanism based on the density function theory as well as QM-MM (quantum mechanics - molecular mechanics) methods, which yield predictions of mechanistic properties such as kinetic isotope effects that appeared consistent with experimental data.
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Affiliation(s)
- Johann Heider
- Laboratory of Microbial Biochemistry, LOEWE Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
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43
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Heider J, Szaleniec M, Martins BM, Seyhan D, Buckel W, Golding BT. Structure and Function of Benzylsuccinate Synthase and Related Fumarate-Adding Glycyl Radical Enzymes. J Mol Microbiol Biotechnol 2016; 26:29-44. [PMID: 26959246 DOI: 10.1159/000441656] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The pathway of anaerobic toluene degradation is initiated by a remarkable radical-type enantiospecific addition of the chemically inert methyl group to the double bond of a fumarate cosubstrate to yield (R)-benzylsuccinate as the first intermediate, as catalyzed by the glycyl radical enzyme benzylsuccinate synthase. In recent years, it has become clear that benzylsuccinate synthase is the prototype enzyme of a much larger family of fumarate-adding enzymes, which play important roles in the anaerobic metabolism of further aromatic and even aliphatic hydrocarbons. We present an overview on the biochemical properties of benzylsuccinate synthase, as well as its recently solved structure, and present the results of an initial structure-based modeling study on the reaction mechanism. Moreover, we compare the structure of benzylsuccinate synthase with those predicted for different clades of fumarate-adding enzymes, in particular the paralogous enzymes converting p-cresol, 2-methylnaphthalene or n-alkanes.
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Affiliation(s)
- Johann Heider
- Laboratory of Microbial Biochemistry, LOEWE Center for Synthetic Microbiology, Philipps University Marburg, Marburg, Germany
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44
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Wilkes H, Buckel W, Golding BT, Rabus R. Metabolism of Hydrocarbons in n-Alkane-Utilizing Anaerobic Bacteria. J Mol Microbiol Biotechnol 2016; 26:138-51. [PMID: 26959725 DOI: 10.1159/000442160] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The glycyl radical enzyme-catalyzed addition of n-alkanes to fumarate creates a C-C-bond between two concomitantly formed stereogenic carbon centers. The configurations of the two diastereoisomers of the product resulting from n-hexane activation by the n-alkane-utilizing denitrifying bacterium strain HxN1, i.e. (1-methylpentyl)succinate, were assigned as (2S,1'R) and (2R,1'R). Experiments with stereospecifically deuterated n-(2,5-2H2)hexanes revealed that exclusively the pro-S hydrogen atom is abstracted from C2 of the n-alkane by the enzyme and later transferred back to C3 of the alkylsuccinate formed. These results indicate that the alkylsuccinate-forming reaction proceeds with an inversion of configuration at the carbon atom (C2) of the n-alkane forming the new C-C-bond, and thus stereochemically resembles a SN2-type reaction. Therefore, the reaction may occur in a concerted manner, which may avoid the highly energetic hex-2-yl radical as an intermediate. The reaction is associated with a significant primary kinetic isotope effect (kH/kD ≥3) for hydrogen, indicating that the homolytic C-H-bond cleavage is involved in the first irreversible step of the reaction mechanism. The (1-methylalkyl)succinate synthases of n-alkane-utilizing anaerobic bacteria apparently have very broad substrate ranges enabling them to activate not only aliphatic but also alkyl-aromatic hydrocarbons. Thus, two denitrifiers and one sulfate reducer were shown to convert the nongrowth substrate toluene to benzylsuccinate and further to the dead-end product benzoyl-CoA. For this purpose, however, the modified β-oxidation pathway known from alkylbenzene-utilizing bacteria was not employed, but rather the pathway used for n-alkane degradation involving CoA ligation, carbon skeleton rearrangement and decarboxylation. Furthermore, various n-alkane- and alkylbenzene-utilizing denitrifiers and sulfate reducers were found to be capable of forming benzyl alcohols from diverse alkylbenzenes, putatively via dehydrogenases. The thermophilic sulfate reducer strain TD3 forms n-alkylsuccinates during growth with n-alkanes or crude oil, which, based on the observed patterns of homologs, do not derive from a terminal activation of n-alkanes.
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Affiliation(s)
- Heinz Wilkes
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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Gittel A, Donhauser J, Røy H, Girguis PR, Jørgensen BB, Kjeldsen KU. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments. Front Microbiol 2015; 6:1414. [PMID: 26733961 PMCID: PMC4681840 DOI: 10.3389/fmicb.2015.01414] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/27/2015] [Indexed: 01/05/2023] Open
Abstract
Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e.g., during prospecting for oil and gas, and may act as an indicator of anthropogenic oil spills in marine sediments.
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Affiliation(s)
- Antje Gittel
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Johanna Donhauser
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Hans Røy
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Peter R Girguis
- Department of Organismic and Evolutionary Biology, Harvard University Cambridge, MA, USA
| | - Bo B Jørgensen
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Kasper U Kjeldsen
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
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Jarling R, Kühner S, Basílio Janke E, Gruner A, Drozdowska M, Golding BT, Rabus R, Wilkes H. Versatile transformations of hydrocarbons in anaerobic bacteria: substrate ranges and regio- and stereo-chemistry of activation reactions. Front Microbiol 2015; 6:880. [PMID: 26441848 PMCID: PMC4561516 DOI: 10.3389/fmicb.2015.00880] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 08/10/2015] [Indexed: 12/31/2022] Open
Abstract
Anaerobic metabolism of hydrocarbons proceeds either via addition to fumarate or by hydroxylation in various microorganisms, e.g., sulfate-reducing or denitrifying bacteria, which are specialized in utilizing n-alkanes or alkylbenzenes as growth substrates. General pathways for carbon assimilation and energy gain have been elucidated for a limited number of possible substrates. In this work the metabolic activity of 11 bacterial strains during anaerobic growth with crude oil was investigated and compared with the metabolite patterns appearing during anaerobic growth with more than 40 different hydrocarbons supplied as binary mixtures. We show that the range of co-metabolically formed alkyl- and arylalkyl-succinates is much broader in n-alkane than in alkylbenzene utilizers. The structures and stereochemistry of these products are resolved. Furthermore, we demonstrate that anaerobic hydroxylation of alkylbenzenes does not only occur in denitrifiers but also in sulfate reducers. We propose that these processes play a role in detoxification under conditions of solvent stress. The thermophilic sulfate-reducing strain TD3 is shown to produce n-alkylsuccinates, which are suggested not to derive from terminal activation of n-alkanes, but rather to represent intermediates of a metabolic pathway short-cutting fumarate regeneration by reverse action of succinate synthase. The outcomes of this study provide a basis for geochemically tracing such processes in natural habitats and contribute to an improved understanding of microbial activity in hydrocarbon-rich anoxic environments.
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Affiliation(s)
- René Jarling
- Organic Geochemistry, Chemistry of the Earth, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Potsdam, Germany
| | - Simon Kühner
- Department of Microbiology, Max Planck Institute for Marine Microbiology Bremen, Germany
| | - Eline Basílio Janke
- Organic Geochemistry, Chemistry of the Earth, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Potsdam, Germany
| | - Andrea Gruner
- Organic Geochemistry, Chemistry of the Earth, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Potsdam, Germany
| | - Marta Drozdowska
- School of Chemistry, Newcastle University Newcastle upon Tyne, UK
| | | | - Ralf Rabus
- Department of Microbiology, Max Planck Institute for Marine Microbiology Bremen, Germany ; General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University Oldenburg, Germany
| | - Heinz Wilkes
- Organic Geochemistry, Chemistry of the Earth, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Potsdam, Germany ; Organic Geochemistry, Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University Oldenburg, Germany
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A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes. Adv Microb Physiol 2015. [PMID: 26210106 DOI: 10.1016/bs.ampbs.2015.05.002] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored.
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Insights into the Anaerobic Biodegradation Pathway of n-Alkanes in Oil Reservoirs by Detection of Signature Metabolites. Sci Rep 2015; 5:9801. [PMID: 25966798 PMCID: PMC4429370 DOI: 10.1038/srep09801] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 03/16/2015] [Indexed: 11/28/2022] Open
Abstract
Anaerobic degradation of alkanes in hydrocarbon-rich environments has been documented
and different degradation strategies proposed, of which the most encountered one is
fumarate addition mechanism, generating alkylsuccinates as specific biomarkers.
However, little is known about the mechanisms of anaerobic degradation of alkanes in
oil reservoirs, due to low concentrations of signature metabolites and lack of mass
spectral characteristics to allow identification. In this work, we used a
multidisciplinary approach combining metabolite profiling and selective gene assays
to establish the biodegradation mechanism of alkanes in oil reservoirs. A total of
twelve production fluids from three different oil reservoirs were collected and
treated with alkali; organic acids were extracted, derivatized with ethanol to form
ethyl esters and determined using GC-MS analysis. Collectively, signature metabolite
alkylsuccinates of parent compounds from C1 to C8 together with their (putative)
downstream metabolites were detected from these samples. Additionally, metabolites
indicative of the anaerobic degradation of mono- and poly-aromatic hydrocarbons
(2-benzylsuccinate, naphthoate, 5,6,7,8-tetrahydro-naphthoate) were also observed.
The detection of alkylsuccinates and genes encoding for alkylsuccinate synthase
shows that anaerobic degradation of alkanes via fumarate addition occurs in oil
reservoirs. This work provides strong evidence on the in situ anaerobic
biodegradation mechanisms of hydrocarbons by fumarate addition.
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A Comprehensive Review of Aliphatic Hydrocarbon Biodegradation by Bacteria. Appl Biochem Biotechnol 2015; 176:670-99. [PMID: 25935219 DOI: 10.1007/s12010-015-1603-5] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 03/31/2015] [Indexed: 02/07/2023]
Abstract
Hydrocarbons are relatively recalcitrant compounds and are classified as high-priority pollutants. However, these compounds are slowly degraded by a large variety of microorganisms. Bacteria are able to degrade aliphatic saturated and unsaturated hydrocarbons via both aerobic and anaerobic pathways. Branched hydrocarbons and cyclic hydrocarbons are also degraded by bacteria. The aerobic bacteria use different types of oxygenases, including monooxygenase, cytochrome-dependent oxygenase and dioxygenase, to insert one or two atoms of oxygen into their targets. Anaerobic bacteria, on the other hand, employ a variety of simple organic and inorganic molecules, including sulphate, nitrate, carbonate and metals, for hydrocarbon oxidation.
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Tan B, Semple K, Foght J. Anaerobic alkane biodegradation by cultures enriched from oil sands tailings ponds involves multiple species capable of fumarate addition. FEMS Microbiol Ecol 2015; 91:fiv042. [PMID: 25873461 DOI: 10.1093/femsec/fiv042] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2015] [Indexed: 01/18/2023] Open
Abstract
A methanogenic short-chain alkane-degrading culture (SCADC) was enriched from oil sands tailings and transferred several times with a mixture of C6, C7, C8 and C10 n-alkanes as the predominant organic carbon source, plus 2-methylpentane, 3-methylpentane and methylcyclopentane as minor components. Cultures produced ∼40% of the maximum theoretical methane during 18 months incubation while depleting the n-alkanes, 2-methylpentane and methylcyclopentane. Substrate depletion correlated with detection of metabolites characteristic of fumarate activation of 2-methylpentane and methylcyclopentane, but not n-alkane metabolites. During active methanogenesis with the mixed alkanes, reverse-transcription PCR confirmed the expression of functional genes (assA and bssA) associated with hydrocarbon addition to fumarate. Pyrosequencing of 16S rRNA genes amplified during active alkane degradation revealed enrichment of Clostridia (particularly Peptococcaceae) and methanogenic Archaea (Methanosaetaceae and Methanomicrobiaceae). Methanogenic cultures transferred into medium containing sulphate produced sulphide, depleted n-alkanes and produced the corresponding succinylated alkane metabolites, but were slow to degrade 2-methylpentane and methylcyclopentane; these cultures were enriched in Deltaproteobacteria rather than Clostridia. 3-Methylpentane was not degraded by any cultures. Thus, nominally methanogenic oil sands tailings harbour dynamic and versatile hydrocarbon-degrading fermentative syntrophs and sulphate reducers capable of degrading n-, iso- and cyclo-alkanes by addition to fumarate.
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Affiliation(s)
- BoonFei Tan
- Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Kathleen Semple
- Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Julia Foght
- Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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