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Ji L, Zhang H, Ding W, Song R, Han Y, Yu H, Paneth P. Theoretical Kinetic Isotope Effects in Establishing the Precise Biodegradation Mechanisms of Organic Pollutants. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:4915-4929. [PMID: 36926881 DOI: 10.1021/acs.est.2c04755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Compound-specific isotope analysis (CSIA) for natural isotope ratios has been recognized as a promising tool to elucidate biodegradation pathways of organic pollutants by microbial enzymes by relating reported kinetic isotope effects (KIEs) to apparent KIEs (AKIEs) derived from bulk isotope fractionations (εbulk). However, for many environmental reactions, neither are the reference KIE ranges sufficiently narrow nor are the mechanisms elucidated to the point that rate-determining steps have been identified unequivocally. In this work, besides providing reference KIEs and rationalizing AKIEs, good relationships have been explained by DFT computations for diverse biodegradation pathways with known enzymatic models between the theoretical isotope fractionations (εbulk') from intrinsic KIEs on the rate-determining steps and the observed εbulk. (1) To confirm the mechanistic details of previously reported pathway-dependent CSIA, it includes isotope changes in MTBE biodegradation between hydroxylation by CYP450 and SN2 reaction by cobalamin-dependent methyltransferase, the regioselectivity of toluene biodegradation by CYP450, and the rate-determining step in toluene biodegradation by benzylsuccinate synthase. (2) To yield new fundamental insights into some unclear biodegradation pathways, it consists of the oxidative function of toluene dioxygenase in biodegradation of TCE, the epoxidation mode in biodegradation of TCE by toluene 4-monooxygenase, and the weighted average mechanism in biodegradation of cDCE by CYP450.
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Affiliation(s)
- Li Ji
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Huanni Zhang
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Wen Ding
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Runqian Song
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Ye Han
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Piotr Paneth
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, Lodz 90-924, Poland
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2
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Lemaire O, Wagner T. A Structural View of Alkyl-Coenzyme M Reductases, the First Step of Alkane Anaerobic Oxidation Catalyzed by Archaea. Biochemistry 2022; 61:805-821. [PMID: 35500274 PMCID: PMC9118554 DOI: 10.1021/acs.biochem.2c00135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/14/2022] [Indexed: 11/28/2022]
Abstract
Microbial anaerobic oxidation of alkanes intrigues the scientific community by way of its impact on the global carbon cycle, and its biotechnological applications. Archaea are proposed to degrade short- and long-chain alkanes to CO2 by reversing methanogenesis, a theoretically reversible process. The pathway would start with alkane activation, an endergonic step catalyzed by methyl-coenzyme M reductase (MCR) homologues that would generate alkyl-thiols carried by coenzyme M. While the methane-generating MCR found in methanogens has been well characterized, the enzymatic activity of the putative alkane-fixing counterparts has not been validated so far. Such an absence of biochemical investigations contrasts with the current explosion of metagenomics data, which draws new potential alkane-oxidizing pathways in various archaeal phyla. Therefore, validating the physiological function of these putative alkane-fixing machines and investigating how their structures, catalytic mechanisms, and cofactors vary depending on the targeted alkane have become urgent needs. The first structural insights into the methane- and ethane-capturing MCRs highlighted unsuspected differences and proposed some explanations for their substrate specificity. This Perspective reviews the current physiological, biochemical, and structural knowledge of alkyl-CoM reductases and offers fresh ideas about the expected mechanistic and chemical differences among members of this broad family. We conclude with the challenges of the investigation of these particular enzymes, which might one day generate biofuels for our modern society.
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Affiliation(s)
- Olivier
N. Lemaire
- Max Planck Institute for
Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Tristan Wagner
- Max Planck Institute for
Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
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3
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Cabral L, Giovanella P, Pellizzer EP, Teramoto EH, Kiang CH, Sette LD. Microbial communities in petroleum-contaminated sites: Structure and metabolisms. CHEMOSPHERE 2022; 286:131752. [PMID: 34426136 DOI: 10.1016/j.chemosphere.2021.131752] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/24/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
Over recent decades, hydrocarbon concentrations have been augmented in soil and water, mainly derived from accidents or operations that input crude oil and petroleum into the environment. Different techniques for remediation have been proposed and used to mitigate oil contamination. Among the available environmental recovery approaches, bioremediation stands out since these hydrocarbon compounds can be used as growth substrates for microorganisms. In turn, microorganisms can play an important role with significant contributions to the stabilization of impacted areas. In this review, we present the current knowledge about responses from natural microbial communities (using DNA barcoding, multiomics, and functional gene markers) and bioremediation experiments (microcosm and mesocosm) conducted in the presence of petroleum and chemical dispersants in different samples, including soil, sediment, and water. Additionally, we present metabolic mechanisms for aerobic/anaerobic hydrocarbon degradation and alternative pathways, as well as a summary of studies showing functional genes and other mechanisms involved in petroleum biodegradation processes.
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Affiliation(s)
- Lucélia Cabral
- Laboratório de Micologia Ambiental e Industrial (LAMAI), Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil
| | - Patricia Giovanella
- Laboratório de Micologia Ambiental e Industrial (LAMAI), Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil; Centro de Estudos Ambientais (CEA), Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil
| | - Elisa Pais Pellizzer
- Laboratório de Micologia Ambiental e Industrial (LAMAI), Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil
| | - Elias Hideo Teramoto
- Centro de Estudos Ambientais (CEA), Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil; Laboratório de Estudos de Bacias (LEBAC), Departamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil
| | - Chang Hung Kiang
- Centro de Estudos Ambientais (CEA), Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil; Laboratório de Estudos de Bacias (LEBAC), Departamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil
| | - Lara Durães Sette
- Laboratório de Micologia Ambiental e Industrial (LAMAI), Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil; Centro de Estudos Ambientais (CEA), Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Rio Claro, SP, Brazil.
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4
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Abstract
Abstract
On the basis of biomimetic, phylometabolic, and thermodynamic analysis of modern CO2 assimilation pathways, a paleophenotypic reconstruction of ancient autotrophic metabolism systems was carried out. As a chemical basis for CO2 fixation paleometabolism, metabolic networks capable of self-reproduction and evolution are considered, and the reversibility of the transformation reactions of its intermediates is the most important factor in self-development of this network. The substances of the C–H–O system, paragenetically associated with hydrocarbons, create a phase space, which is a set of universal intermediates of the autotrophic paleometabolism chemical network. The concept of two strategies for the origin and development of autotrophic carbon fixation paleometabolism in the oxidized (CO2) and reduced (CH4) redox regimes of degassing of the ancient Earth is proposed. It was shown that P, T, and the redox conditions of hydrothermal systems of the early Archean were favorable for the development of primary methanotrophic metabolism.
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Cheng C, Shen X, Xie H, Hu Z, Pavlostathis SG, Zhang J. Coupled methane and nitrous oxide biotransformation in freshwater wetland sediment microcosms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 648:916-922. [PMID: 30144759 DOI: 10.1016/j.scitotenv.2018.08.185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/24/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
Anaerobic oxidation of methane (AOM) coupled to denitrification is becoming the focus of scientific inquiry due to its potential contribution to global carbon and nitrogen cycles. AOM has been previously reported to proceed with nitrate (NO3-) or nitrite (NO2-). However, little research has been conducted on the simultaneous use of methane (CH4) and nitrous oxide (N2O). Here, coupled CH4 and N2O biotransformation in a freshwater wetland sediment was obtained in a 7-day anaerobic sediment incubation assay. The significant CO2 accumulation and decrease of CH4 emission in sediment microcosms was attributed to two mechanisms: inhibition of methanogenesis and N2O-dependent AOM. To further confirm the coupled CH4 and N2O transformation, a 13C-labelled stable isotope tracer assay after anaerobic incubation was conducted with N2O and/or CH4 amendments. The N2O-dependent AOM rate was 3.41 ± 0.13 nmol CO2 g-1 dry sediment·day-1. According to metagenomic analysis, addition of N2O stimulated AOM by increasing the activity and abundance of methanotrophic bacteria and by increasing enzymatic activities in the electron transport chain. Based on these results, we propose coupled CH4 and N2O biotransformation in the sediment microcosms for the first time, carried out by unidentified methanotroph(s) via intra‑oxygen produced in the presence of N2O. Such a process has the potential to reduce the emission of two highly potent greenhouse gases and makes a significant contribution to the link of global carbon and nitrogen cycles in anoxic environments.
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Affiliation(s)
- Cheng Cheng
- School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Xuanxu Shen
- School of Environmental Science and Engineering, Shandong University, Jinan 250100, China
| | - Huijun Xie
- Environmental Research Institute, Shandong University, Jinan 250100, China
| | - Zhen Hu
- School of Environmental Science and Engineering, Shandong University, Jinan 250100, China
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Jian Zhang
- School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
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Abstract
Twenty-five years ago this month, Thomas Gold published a seminal manuscript suggesting the presence of a "deep, hot biosphere" in the Earth's crust. Since this publication, a considerable amount of attention has been given to the study of deep biospheres, their role in geochemical cycles, and their potential to inform on the origin of life and its potential outside of Earth. Overwhelming evidence now supports the presence of a deep biosphere ubiquitously distributed on Earth in both terrestrial and marine settings. Furthermore, it has become apparent that much of this life is dependent on lithogenically sourced high-energy compounds to sustain productivity. A vast diversity of uncultivated microorganisms has been detected in subsurface environments, and we show that H2, CH4, and CO feature prominently in many of their predicted metabolisms. Despite 25 years of intense study, key questions remain on life in the deep subsurface, including whether it is endemic and the extent of its involvement in the anaerobic formation and degradation of hydrocarbons. Emergent data from cultivation and next-generation sequencing approaches continue to provide promising new hints to answer these questions. As Gold suggested, and as has become increasingly evident, to better understand the subsurface is critical to further understanding the Earth, life, the evolution of life, and the potential for life elsewhere. To this end, we suggest the need to develop a robust network of interdisciplinary scientists and accessible field sites for long-term monitoring of the Earth's subsurface in the form of a deep subsurface microbiome initiative.
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Espínola F, Dionisi HM, Borglin S, Brislawn CJ, Jansson JK, Mac Cormack WP, Carroll J, Sjöling S, Lozada M. Metagenomic Analysis of Subtidal Sediments from Polar and Subpolar Coastal Environments Highlights the Relevance of Anaerobic Hydrocarbon Degradation Processes. MICROBIAL ECOLOGY 2018; 75:123-139. [PMID: 28702706 DOI: 10.1007/s00248-017-1028-5] [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: 05/06/2017] [Accepted: 06/27/2017] [Indexed: 06/07/2023]
Abstract
In this work, we analyzed the community structure and metabolic potential of sediment microbial communities in high-latitude coastal environments subjected to low to moderate levels of chronic pollution. Subtidal sediments from four low-energy inlets located in polar and subpolar regions from both Hemispheres were analyzed using large-scale 16S rRNA gene and metagenomic sequencing. Communities showed high diversity (Shannon's index 6.8 to 10.2), with distinct phylogenetic structures (<40% shared taxa at the Phylum level among regions) but similar metabolic potential in terms of sequences assigned to KOs. Environmental factors (mainly salinity, temperature, and in less extent organic pollution) were drivers of both phylogenetic and functional traits. Bacterial taxa correlating with hydrocarbon pollution included families of anaerobic or facultative anaerobic lifestyle, such as Desulfuromonadaceae, Geobacteraceae, and Rhodocyclaceae. In accordance, biomarker genes for anaerobic hydrocarbon degradation (bamA, ebdA, bcrA, and bssA) were prevalent, only outnumbered by alkB, and their sequences were taxonomically binned to the same bacterial groups. BssA-assigned metagenomic sequences showed an extremely wide diversity distributed all along the phylogeny known for this gene, including bssA sensu stricto, nmsA, assA, and other clusters from poorly or not yet described variants. This work increases our understanding of microbial community patterns in cold coastal sediments, and highlights the relevance of anaerobic hydrocarbon degradation processes in subtidal environments.
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Affiliation(s)
- Fernando Espínola
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Centro Nacional Patagónico, Blvd. Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina
| | - Hebe M Dionisi
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Centro Nacional Patagónico, Blvd. Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina
| | - Sharon Borglin
- Energy Geosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Colin J Brislawn
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Janet K Jansson
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Walter P Mac Cormack
- Instituto Nanobiotec, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
- Instituto Antártico Argentino, Buenos Aires, Argentina
| | - JoLynn Carroll
- Akvaplan-niva, Fram-High North Research Centre for Climate and the Environment, and ARCEx-Research Centre for Arctic Petroleum Exploration, Department of Geosciences, UiT The Arctic University of Norway, N-9037, Tromsø, Norway
| | - Sara Sjöling
- School of Natural Sciences and Environmental Studies, Södertörn University, Huddinge, Sweden
| | - Mariana Lozada
- Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Centro Nacional Patagónico, Blvd. Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina.
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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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9
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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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Funk MA, Marsh ENG, Drennan CL. Substrate-bound structures of benzylsuccinate synthase reveal how toluene is activated in anaerobic hydrocarbon degradation. J Biol Chem 2015. [PMID: 26224635 DOI: 10.1074/jbc.m115.670737] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Various bacteria perform anaerobic degradation of small hydrocarbons as a source of energy and cellular carbon. To activate non-reactive hydrocarbons such as toluene, enzymes conjugate these molecules to fumarate in a radical-catalyzed, C-C bond-forming reaction. We have determined x-ray crystal structures of the glycyl radical enzyme that catalyzes the addition of toluene to fumarate, benzylsuccinate synthase (BSS), in two oligomeric states with fumarate alone or with both substrates. We find that fumarate is secured at the bottom of a long active site cavity with toluene bound directly above it. The two substrates adopt orientations that appear ideal for radical-mediated C-C bond formation; the methyl group of toluene is positioned between fumarate and a cysteine that forms a thiyl radical during catalysis, which is in turn adjacent to the glycine that serves as a radical storage residue. Toluene is held in place by fumarate on one face and tight packing by hydrophobic residues on the other face and sides. These hydrophobic residues appear to become ordered, thus encapsulating toluene, only in the presence of BSSβ, a small protein subunit that forms a tight complex with BSSα, the catalytic subunit. Enzymes related to BSS are able to metabolize a wide range of hydrocarbons through attachment to fumarate. Using our structures as a guide, we have constructed homology models of several of these "X-succinate synthases" and determined conservation patterns that will be useful in understanding the basis for catalysis and specificity in this family of enzymes.
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Affiliation(s)
| | - E Neil G Marsh
- the Department of Chemistry and Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Catherine L Drennan
- From the Departments of Chemistry and Biology and the Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
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11
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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: 164] [Impact Index Per Article: 18.2] [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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12
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Mueller TJ, Grisewood MJ, Nazem-Bokaee H, Gopalakrishnan S, Ferry JG, Wood TK, Maranas CD. Methane oxidation by anaerobic archaea for conversion to liquid fuels. ACTA ACUST UNITED AC 2015; 42:391-401. [DOI: 10.1007/s10295-014-1548-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/11/2014] [Indexed: 11/24/2022]
Abstract
Abstract
Given the recent increases in natural gas reserves and associated drawbacks of current gas-to-liquids technologies, the development of a bioconversion process to directly convert methane to liquid fuels would generate considerable industrial interest. Several clades of anaerobic methanotrophic archaea (ANME) are capable of performing anaerobic oxidation of methane (AOM). AOM carried out by ANME offers carbon efficiency advantages over aerobic oxidation by conserving the entire carbon flux without losing one out of three carbon atoms to carbon dioxide. This review highlights the recent advances in understanding the key enzymes involved in AOM (i.e., methyl-coenzyme M reductase), the ecological niches of a number of ANME, the putative metabolic pathways for AOM, and the syntrophic consortia that they typically form.
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Affiliation(s)
- Thomas J Mueller
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
| | - Matthew J Grisewood
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
| | - Hadi Nazem-Bokaee
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
| | - Saratram Gopalakrishnan
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
| | - James G Ferry
- grid.29857.31 0000000120974281 Department of Biochemistry and Molecular Biology The Pennsylvania State University University Park PA USA
| | - Thomas K Wood
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
- grid.29857.31 0000000120974281 Department of Biochemistry and Molecular Biology The Pennsylvania State University University Park PA USA
| | - Costas D Maranas
- grid.29857.31 0000000120974281 Department of Chemical Engineering The Pennsylvania State University University Park PA USA
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13
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Agrawal A, Gieg LM. In situ detection of anaerobic alkane metabolites in subsurface environments. Front Microbiol 2013; 4:140. [PMID: 23761789 PMCID: PMC3671572 DOI: 10.3389/fmicb.2013.00140] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/17/2013] [Indexed: 11/13/2022] Open
Abstract
Alkanes comprise a substantial fraction of crude oil and refined fuels. As such, they are prevalent within deep subsurface fossil fuel deposits and in shallow subsurface environments such as aquifers that are contaminated with hydrocarbons. These environments are typically anaerobic, and host diverse microbial communities that can potentially use alkanes as substrates. Anaerobic alkane biodegradation has been reported to occur under nitrate-reducing, sulfate-reducing, and methanogenic conditions. Elucidating the pathways of anaerobic alkane metabolism has been of interest in order to understand how microbes can be used to remediate contaminated sites. Alkane activation primarily occurs by addition to fumarate, yielding alkylsuccinates, unique anaerobic metabolites that can be used to indicate in situ anaerobic alkane metabolism. These metabolites have been detected in hydrocarbon-contaminated shallow aquifers, offering strong evidence for intrinsic anaerobic bioremediation. Recently, studies have also revealed that alkylsuccinates are present in oil and coal seam production waters, indicating that anaerobic microbial communities can utilize alkanes in these deeper subsurface environments. In many crude oil reservoirs, the in situ anaerobic metabolism of hydrocarbons such as alkanes may be contributing to modern-day detrimental effects such as oilfield souring, or may lead to more beneficial technologies such as enhanced energy recovery from mature oilfields. In this review, we briefly describe the key metabolic pathways for anaerobic alkane (including n-alkanes, isoalkanes, and cyclic alkanes) metabolism and highlight several field reports wherein alkylsuccinates have provided evidence for anaerobic in situ alkane metabolism in shallow and deep subsurface environments.
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Affiliation(s)
- Akhil Agrawal
- Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary Calgary, AB, Canada
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Callaghan AV. Enzymes involved in the anaerobic oxidation of n-alkanes: from methane to long-chain paraffins. Front Microbiol 2013; 4:89. [PMID: 23717304 PMCID: PMC3653055 DOI: 10.3389/fmicb.2013.00089] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 03/31/2013] [Indexed: 11/13/2022] Open
Abstract
Anaerobic microorganisms play key roles in the biogeochemical cycling of methane and non-methane alkanes. To date, there appear to be at least three proposed mechanisms of anaerobic methane oxidation (AOM). The first pathway is mediated by consortia of archaeal anaerobic methane oxidizers and sulfate-reducing bacteria (SRB) via “reverse methanogenesis” and is catalyzed by a homolog of methyl-coenzyme M reductase. The second pathway is also mediated by anaerobic methane oxidizers and SRB, wherein the archaeal members catalyze both methane oxidation and sulfate reduction and zero-valent sulfur is a key intermediate. The third AOM mechanism is a nitrite-dependent, “intra-aerobic” pathway described for the denitrifying bacterium, ‘Candidatus Methylomirabilis oxyfera.’ It is hypothesized that AOM proceeds via reduction of nitrite to nitric oxide, followed by the conversion of two nitric oxide molecules to dinitrogen and molecular oxygen. The latter can be used to functionalize the methane via a particulate methane monooxygenase. With respect to non-methane alkanes, there also appear to be novel mechanisms of activation. The most well-described pathway is the addition of non-methane alkanes across the double bond of fumarate to form alkyl-substituted succinates via the putative glycyl radical enzyme, alkylsuccinate synthase (also known as methylalkylsuccinate synthase). Other proposed mechanisms include anaerobic hydroxylation via ethylbenzene dehydrogenase-like enzymes and an “intra-aerobic” denitrification pathway similar to that described for ‘Methylomirabilis oxyfera.’
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Affiliation(s)
- Amy V Callaghan
- Department of Microbiology and Plant Biology, University of Oklahoma Norman, OK, USA
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