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Awala SI, Gwak JH, Kim Y, Jung MY, Dunfield PF, Wagner M, Rhee SK. Nitrous oxide respiration in acidophilic methanotrophs. Nat Commun 2024; 15:4226. [PMID: 38762502 PMCID: PMC11102522 DOI: 10.1038/s41467-024-48161-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 04/22/2024] [Indexed: 05/20/2024] Open
Abstract
Aerobic methanotrophic bacteria are considered strict aerobes but are often highly abundant in hypoxic and even anoxic environments. Despite possessing denitrification genes, it remains to be verified whether denitrification contributes to their growth. Here, we show that acidophilic methanotrophs can respire nitrous oxide (N2O) and grow anaerobically on diverse non-methane substrates, including methanol, C-C substrates, and hydrogen. We study two strains that possess N2O reductase genes: Methylocella tundrae T4 and Methylacidiphilum caldifontis IT6. We show that N2O respiration supports growth of Methylacidiphilum caldifontis at an extremely acidic pH of 2.0, exceeding the known physiological pH limits for microbial N2O consumption. Methylocella tundrae simultaneously consumes N2O and CH4 in suboxic conditions, indicating robustness of its N2O reductase activity in the presence of O2. Furthermore, in O2-limiting conditions, the amount of CH4 oxidized per O2 reduced increases when N2O is added, indicating that Methylocella tundrae can direct more O2 towards methane monooxygenase. Thus, our results demonstrate that some methanotrophs can respire N2O independently or simultaneously with O2, which may facilitate their growth and survival in dynamic environments. Such metabolic capability enables these bacteria to simultaneously reduce the release of the key greenhouse gases CO2, CH4, and N2O.
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Affiliation(s)
- Samuel Imisi Awala
- Department of Biological Sciences and Biotechnology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju, 28644, Republic of Korea
- Center for Ecology and Environmental Toxicology, Chungbuk National University, 1 Chungdae-Ro, Seowon-Gu, Cheongju, 28644, South Korea
| | - Joo-Han Gwak
- Department of Biological Sciences and Biotechnology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju, 28644, Republic of Korea
| | - Yongman Kim
- Department of Biological Sciences and Biotechnology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju, 28644, Republic of Korea
| | - Man-Young Jung
- Interdisciplinary Graduate Programme in Advance Convergence Technology and Science, Jeju National University, Jeju, Republic of Korea
- Department of Science Education, Jeju National University, Jeju, Republic of Korea
- Jeju Microbiome Center, Jeju National University, Jeju, Republic of Korea
| | - Peter F Dunfield
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Michael Wagner
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg, Denmark
| | - Sung-Keun Rhee
- Department of Biological Sciences and Biotechnology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju, 28644, Republic of Korea.
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Matsen JB, Yang S, Stein LY, Beck D, Kalyuzhnaya MG. Global Molecular Analyses of Methane Metabolism in Methanotrophic Alphaproteobacterium, Methylosinus trichosporium OB3b. Part I: Transcriptomic Study. Front Microbiol 2013; 4:40. [PMID: 23565111 PMCID: PMC3615186 DOI: 10.3389/fmicb.2013.00040] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 02/17/2013] [Indexed: 11/20/2022] Open
Abstract
Methane utilizing bacteria (methanotrophs) are important in both environmental and biotechnological applications, due to their ability to convert methane to multicarbon compounds. However, systems-level studies of methane metabolism have not been carried out in methanotrophs. In this work we have integrated genomic and transcriptomic information to provide an overview of central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotroph. Particulate methane monooxygenase, PQQ-dependent methanol dehydrogenase, the H4MPT-pathway, and NAD-dependent formate dehydrogenase are involved in methane oxidation to CO2. All genes essential for operation of the serine cycle, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle were expressed. PEP-pyruvate-oxaloacetate interconversions may have a function in regulation and balancing carbon between the serine cycle and the EMC pathway. A set of transaminases may contribute to carbon partitioning between the pathways. Metabolic pathways for acquisition and/or assimilation of nitrogen and iron are discussed.
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Affiliation(s)
- Janet B Matsen
- Department of Chemical Engineering, University of Washington Seattle, WA, USA
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Graham DW, Kim HJ. Production, isolation, purification, and functional characterization of methanobactins. Methods Enzymol 2011; 495:227-45. [PMID: 21419925 DOI: 10.1016/b978-0-12-386905-0.00015-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aerobic methane-oxidizing bacteria (methanotrophs) have a high conditional need for copper because almost all known species express a copper-containing particulate methane monooxygenase for catalyzing the conversion of methane to methanol. This demands a copper homeostatic system that must both supply and satisfy adequate copper for elevated needs while also shielding the cells from copper toxicity. After considerable effort, it was discovered that some methanotrophs produce small peptidic molecules, called methanobactins, which bind copper, mediate copper transport into the cell, and reduce copper toxicity. Unfortunately, isolating, purifying, and proving the functionality of these molecules has been challenging. In fact, until very recently, only one complete structure had been reported for methanobactins. As such, there is a desperate need for more studies seeking such molecules. The purpose of this chapter is to describe methods used to isolate and purify the original methanobactin with a published complete structure, which is made by Methylosinus trichosporium OB3b. Methods are also included for assessing the function of such molecules under pseudonatural conditions such as growth on mineral copper sources. Special emphasis is placed on verifying that isolated molecules are "true" methanobactins, because recent work has shown that methanotrophs produce other small molecules that also bind metals in solution.
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Affiliation(s)
- David W Graham
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle Upon Tyne, United Kingdom
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Kim HJ, Graham DW, DiSpirito AA, Alterman MA, Galeva N, Larive CK, Asunskis D, Sherwood PMA. Methanobactin, a copper-acquisition compound from methane-oxidizing bacteria. Science 2004; 305:1612-5. [PMID: 15361623 DOI: 10.1126/science.1098322] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Siderophores are extracellular iron-binding compounds that mediate iron transport into many cells. We present evidence of analogous molecules for copper transport from methane-oxidizing bacteria, represented here by a small fluorescent chromopeptide (C45N12O14H62Cu, 1216 daltons) produced by Methylosinus trichosporium OB3b. The crystal structure of this compound, methanobactin, was resolved to 1.15 angstroms. It is composed of a tetrapeptide, a tripeptide, and several unusual moieties, including two 4-thionyl-5-hydroxy-imidazole chromophores that coordinate the copper, a pyrrolidine that confers a bend in the overall chain, and an amino-terminal isopropylester group. The copper coordination environment includes a dual nitrogen- and sulfur-donating system derived from the thionyl imidazolate moieties. Structural elucidation of this molecule has broad implications in terms of organo-copper chemistry, biological methane oxidation, and global carbon cycling.
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Affiliation(s)
- Hyung J Kim
- Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA
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