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Mao Z, Fleming JR, Mayans O, Frey J, Schleheck D, Schink B, Müller N. AMP-dependent phosphite dehydrogenase, a phosphorylating enzyme in dissimilatory phosphite oxidation. Proc Natl Acad Sci U S A 2023; 120:e2309743120. [PMID: 37922328 PMCID: PMC10636320 DOI: 10.1073/pnas.2309743120] [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: 06/14/2023] [Accepted: 09/20/2023] [Indexed: 11/05/2023] Open
Abstract
Oxidation of phosphite (HPO32-) to phosphate (HPO42-) releases electrons at a very low redox potential (E0'= -690 mV) which renders phosphite an excellent electron donor for microbial energy metabolism. To date, two pure cultures of strictly anaerobic bacteria have been isolated that run their energy metabolism on the basis of phosphite oxidation, the Gram-negative Desulfotignum phosphitoxidans (DSM 13687) and the Gram-positive Phosphitispora fastidiosa (DSM 112739). Here, we describe the key enzyme for dissimilatory phosphite oxidation in these bacteria. The enzyme catalyzed phosphite oxidation in the presence of adenosine monophosphate (AMP) to form adenosine diphosphate (ADP), with concomitant reduction of oxidized nicotinamide adenine dinucleotide (NAD+) to reduced nicotinamide adenine dinucleotide (NADH). The enzyme of P. fastidiosa was heterologously expressed in Escherichia coli. It has a molecular mass of 35.2 kDa and a high affinity for phosphite and NAD+. Its activity was enhanced more than 100-fold by addition of ADP-consuming adenylate kinase (myokinase) to a maximal activity between 30 and 80 mU x mg protein-1. A similar NAD-dependent enzyme oxidizing phosphite to phosphate with concomitant phosphorylation of AMP to ADP is found in D. phosphitoxidans, but this enzyme could not be heterologously expressed. Based on sequence analysis, these phosphite-oxidizing enzymes are related to nucleotide-diphosphate-sugar epimerases and indeed represent AMP-dependent phosphite dehydrogenases (ApdA). A reaction mechanism is proposed for this unusual type of substrate-level phosphorylation reaction.
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Affiliation(s)
- Zhuqing Mao
- Department of Biology, University of Konstanz, Constance78457, Germany
- Konstanz Research School Chemical Biology, Departments of Chemistry and Biology, University of Konstanz, Constance78457, Germany
| | - Jennifer R. Fleming
- Department of Biology, University of Konstanz, Constance78457, Germany
- Konstanz Research School Chemical Biology, Departments of Chemistry and Biology, University of Konstanz, Constance78457, Germany
| | - Olga Mayans
- Department of Biology, University of Konstanz, Constance78457, Germany
- Konstanz Research School Chemical Biology, Departments of Chemistry and Biology, University of Konstanz, Constance78457, Germany
| | - Jasmin Frey
- Department of Biology, University of Konstanz, Constance78457, Germany
| | - David Schleheck
- Department of Biology, University of Konstanz, Constance78457, Germany
- Konstanz Research School Chemical Biology, Departments of Chemistry and Biology, University of Konstanz, Constance78457, Germany
| | - Bernhard Schink
- Department of Biology, University of Konstanz, Constance78457, Germany
- Konstanz Research School Chemical Biology, Departments of Chemistry and Biology, University of Konstanz, Constance78457, Germany
| | - Nicolai Müller
- Department of Biology, University of Konstanz, Constance78457, Germany
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Singh A, Schnürer A, Dolfing J, Westerholm M. Syntrophic entanglements for propionate and acetate oxidation under thermophilic and high-ammonia conditions. THE ISME JOURNAL 2023; 17:1966-1978. [PMID: 37679429 PMCID: PMC10579422 DOI: 10.1038/s41396-023-01504-y] [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: 03/17/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023]
Abstract
Propionate is a key intermediate in anaerobic digestion processes and often accumulates in association with perturbations, such as elevated levels of ammonia. Under such conditions, syntrophic ammonia-tolerant microorganisms play a key role in propionate degradation. Despite their importance, little is known about these syntrophic microorganisms and their cross-species interactions. Here, we present metagenomes and metatranscriptomic data for novel thermophilic and ammonia-tolerant syntrophic bacteria and the partner methanogens enriched in propionate-fed reactors. A metagenome for a novel bacterium for which we propose the provisional name 'Candidatus Thermosyntrophopropionicum ammoniitolerans' was recovered, together with mapping of its highly expressed methylmalonyl-CoA pathway for syntrophic propionate degradation. Acetate was degraded by a novel thermophilic syntrophic acetate-oxidising candidate bacterium. Electron removal associated with syntrophic propionate and acetate oxidation was mediated by the hydrogen/formate-utilising methanogens Methanoculleus sp. and Methanothermobacter sp., with the latter observed to be critical for efficient propionate degradation. Similar dependence on Methanothermobacter was not seen for acetate degradation. Expression-based analyses indicated use of both H2 and formate for electron transfer, including cross-species reciprocation with sulphuric compounds and microbial nanotube-mediated interspecies interactions. Batch cultivation demonstrated degradation rates of up to 0.16 g propionate L-1 day-1 at hydrogen partial pressure 4-30 Pa and available energy was around -20 mol-1 propionate. These observations outline the multiple syntrophic interactions required for propionate oxidation and represent a first step in increasing knowledge of acid accumulation in high-ammonia biogas production systems.
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Affiliation(s)
- Abhijeet Singh
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden
| | - Anna Schnürer
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden
| | - Jan Dolfing
- Faculty of Energy and Environment, Northumbria University, Newcastle-upon-Tyne, NE18QH, UK
| | - Maria Westerholm
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
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Frolov EN, Gavrilov SN, Toshchakov SV, Zavarzina DG. Genomic Insights into Syntrophic Lifestyle of ' Candidatus Contubernalis alkaliaceticus' Based on the Reversed Wood-Ljungdahl Pathway and Mechanism of Direct Electron Transfer. Life (Basel) 2023; 13:2084. [PMID: 37895465 PMCID: PMC10608574 DOI: 10.3390/life13102084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
The anaerobic oxidation of fatty acids and alcohols occurs near the thermodynamic limit of life. This process is driven by syntrophic bacteria that oxidize fatty acids and/or alcohols, their syntrophic partners that consume the products of this oxidation, and the pathways for interspecies electron exchange via these products or direct interspecies electron transfer (DIET). Due to the interdependence of syntrophic microorganisms on each other's metabolic activity, their isolation in pure cultures is almost impossible. Thus, little is known about their physiology, and the only available way to fill in the knowledge gap on these organisms is genomic and metabolic analysis of syntrophic cultures. Here we report the results of genome sequencing and analysis of an obligately syntrophic alkaliphilic bacterium 'Candidatus Contubernalis alkaliaceticus'. The genomic data suggest that acetate oxidation is carried out by the Wood-Ljungdahl pathway, while a bimodular respiratory system involving an Rnf complex and a Na+-dependent ATP synthase is used for energy conservation. The predicted genomic ability of 'Ca. C. alkaliaceticus' to outperform interspecies electron transfer both indirectly, via H2 or formate, and directly, via pili-like appendages of its syntrophic partner or conductive mineral particles, was experimentally demonstrated. This is the first indication of DIET in the class Dethiobacteria.
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Affiliation(s)
- Evgenii N. Frolov
- Winogradsky Institute of Microbiology, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 60 Let Oktjabrja Pr-t, 7, Bld. 2, Moscow 117312, Russia; (S.N.G.); (D.G.Z.)
| | - Sergey N. Gavrilov
- Winogradsky Institute of Microbiology, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 60 Let Oktjabrja Pr-t, 7, Bld. 2, Moscow 117312, Russia; (S.N.G.); (D.G.Z.)
| | - Stepan V. Toshchakov
- National Research Centre “Kurchatov Institute”, Akademika Kurchatova Sq., 1, Moscow 123182, Russia;
| | - Daria G. Zavarzina
- Winogradsky Institute of Microbiology, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 60 Let Oktjabrja Pr-t, 7, Bld. 2, Moscow 117312, Russia; (S.N.G.); (D.G.Z.)
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Van De Ven CJC, Laurenzi L, Arnold AC, Hallam SJ, Mayer KU. The nature of gas production patterns associated with methanol degradation in natural aquifer sediments: A microcosm study. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 247:103988. [PMID: 35303484 DOI: 10.1016/j.jconhyd.2022.103988] [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: 09/21/2020] [Revised: 02/28/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
With growing global use of methanol as a fuel additive and extensive use in other industrial processes, there is the potential for unintended release and spills into soils and aquifers. In these subsurface systems it is likely that methanol will be readily biodegraded; however, degradation may lead to the production of by-products, most importantly methane possibly resulting in explosion hazards and volatile fatty acids (VFAs) causing aesthetic issues for groundwater. In this study, the formation of these potentially harmful by-products due to methanol biodegradation was investigated in natural sand and silt sediments using microcosms inoculated with neat methanol (100%) ranging in concentration from 100 to 100,000 ppm. To assess the rate of degradation and by-product formation, water and headspace samples were collected and analyzed for methanol, volatile fatty acids (VFAs, including acetic, butyric, and propionic acid), cation (metal) concentrations (Al, Ca, Fe, K, Mg, Mn and Na), microbial community structure and activity, headspace pressure, gas composition (CH4, CO2, O2 and N2), and compound specific isotopes. Methanol was completely biodegraded in sand and silt up to concentrations of 1000 ppm and 10,000 ppm, respectively. Degradation was initially aerobic, consuming oxygen (O2) and producing carbon dioxide (CO2). When O2 was depleted, the microcosms became anaerobic and a lag in methanol degradation occurred (ranging from 41 to 87 days). Following this lag, methanol was preferentially degraded to acetate, coupled with CO2 reduction. Microcosms with high methanol concentrations (10,000 ppm) were driven further down the redox ladder and exhibited fermentation, leading to concurrent acetate and methane (CH4) generation. In all cases acetate was an intermediate product, further degraded to the final products of CH4 and CO2. Carbonates present in the microcosm sediments helped buffer VFA acidification and replenished CO2. Methane generation in the anaerobic microcosms was short-lived, but temporarily reached high rates up to 13 mg kg-1 day-1. Under the conditions of these experiments, methanol degradation occurred rapidly, after initial lag periods, which were a function of methanol concentration and sediment type. Our experiment also showed that methanol degradation and associated methane production can occur in a stepwise fashion.
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Affiliation(s)
- Cole J C Van De Ven
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Carleton University, Department of Civil & Environmental Engineering, Ottawa, ON K1S 5B6, Canada.
| | - Laura Laurenzi
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Ashley C Arnold
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Steven J Hallam
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Graduate Program in Bioinformatics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Genome Sciences Centre, BC Cancer Agency, Vancouver, BC V5Z 4S6, Canada; Genome Science and Technology Program, University of British Columbia, 2329 West Mall, Vancouver, BC V6T 1Z4, Canada; Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; ECOSCOPE Training Program, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - K Ulrich Mayer
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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Marcel M, Darina E, Patrick K, Aline H, Gabriele P, Stefan J, Jochen B. Impact of different trace elements on metabolic routes during heterotrophic growth of C. ljungdahlii investigated through online measurement of the carbon dioxide transfer rate. Biotechnol Prog 2022; 38:e3263. [PMID: 35434968 DOI: 10.1002/btpr.3263] [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: 01/27/2022] [Revised: 03/30/2022] [Accepted: 04/15/2022] [Indexed: 11/09/2022]
Abstract
Synthesis gas fermentation using acetogenic clostridia is a rapidly increasing research area. It offers the possibility to produce platform chemicals from sustainable C1 carbon sources. The Wood-Ljungdahl pathway (WLP), which allows acetogens to grow autotrophically, is also active during heterotrophic growth. It acts as an electron sink and allows for the utilization of a wide variety of soluble substrates and increases ATP yields during heterotrophic growth. While glycolysis leads to CO2 evolution, WLP activity results in CO2 fixation. Thus, a reduction of net CO2 emissions during growth with sugars is an indicator of WLP activity. To study the effect of trace elements and ventilation rates on the interaction between glycolysis and the WLP, the model acetogen Clostridium ljungdahlii was cultivated in YTF medium, a complex medium generally employed for heterotrophic growth, with fructose as growth substrate. The recently reported anaRAMOS device was used for online measurement of metabolic activity, in form of CO2 evolution. The addition of multiple trace elements (iron, cobalt, manganese, zinc, nickel, copper, selenium, and tungsten) was tested, to study the interaction between glycolysis and the Wood ljungdahl pathway. While the addition of iron(II) increased growth rates and ethanol production, added nickel(II) increased WLP activity and acetate formation, reducing net CO2 production by 28%. Also, higher CO2 availability through reduced volumetric gas flow resulted in 25% reduction of CO2 evolution. These online metabolic data demonstrate that the anaRAMOS is a valuable tool in the investigation of metabolic responses i.e. to determine nutrient requirements that results in reduced CO2 production. Thereby the media composition can be optimized depending on the specific goal. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mann Marcel
- RWTH Aachen University, AVT - Biochemical Engineering, Aachen, Germany
| | - Effert Darina
- RWTH Aachen University, AVT - Biochemical Engineering, Aachen, Germany
| | - Kottenhahn Patrick
- RWTH Aachen University, AVT - Biochemical Engineering, Aachen, Germany.,Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, Aachen, Germany
| | - Hüser Aline
- RWTH Aachen University, AVT - Biochemical Engineering, Aachen, Germany
| | - Philipps Gabriele
- Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, Aachen, Germany
| | - Jennewein Stefan
- Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, Aachen, Germany
| | - Büchs Jochen
- RWTH Aachen University, AVT - Biochemical Engineering, Aachen, Germany
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De Vrieze J, Heyer R, Props R, Van Meulebroek L, Gille K, Vanhaecke L, Benndorf D, Boon N. Triangulation of microbial fingerprinting in anaerobic digestion reveals consistent fingerprinting profiles. WATER RESEARCH 2021; 202:117422. [PMID: 34280807 DOI: 10.1016/j.watres.2021.117422] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/01/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
The anaerobic digestion microbiome has been puzzling us since the dawn of molecular methods for mixed microbial community analysis. Monitoring of the anaerobic digestion microbiome can either take place via a non-targeted holistic evaluation of the microbial community through fingerprinting or by targeted monitoring of selected taxa. Here, we compared four different microbial community fingerprinting methods, i.e., amplicon sequencing, metaproteomics, metabolomics and cytomics, in their ability to characterise the full-scale anaerobic digestion microbiome. Cytometric fingerprinting through cytomics reflects a, for anaerobic digestion, novel, single cell-based approach of direct microbial community fingerprinting by flow cytometry. Three different digester types, i.e., sludge digesters, digesters treating agro-industrial waste and dry anaerobic digesters, each reflected different operational parameters. The α-diversity analysis yielded inconsistent results, especially for richness, across the different methods. In contrast, β-diversity analysis resulted in comparable profiles, even when translated into phyla or functions, with clear separation of the three digester types. In-depth analysis of each method's features i.e., operational taxonomic units, metaproteins, metabolites, and cytometric traits, yielded certain similar features, yet, also some clear differences between the different methods, which was related to the complexity of the anaerobic digestion process. In conclusion, cytometric fingerprinting through flow cytometry is a reliable, fast method for holistic monitoring of the anaerobic digestion microbiome, and the complementary identification of key features through other methods could give rise to a direct interpretation of anaerobic digestion process performance.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium; Division of Soil and Water Management, Department of Earth and Environmental sciences, KU Leuven, Kasteelpark Arenberg 20, PO box 2411, B-3001, Leuven, Belgium; Bio- and Chemical Systems Technology, Reactor Engineering and Safety (CREaS), Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200F, PO box 2424, B-3001, Leuven, Belgium.
| | - Robert Heyer
- Bioprocess Engineering, Otto von Guericke University, Universitätsplatz 2, 39106, Magdeburg, Germany
| | - Ruben Props
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium
| | - Lieven Van Meulebroek
- Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Karen Gille
- Bioprocess Engineering, Otto von Guericke University, Universitätsplatz 2, 39106, Magdeburg, Germany
| | - Lynn Vanhaecke
- Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Dirk Benndorf
- Bioprocess Engineering, Otto von Guericke University, Universitätsplatz 2, 39106, Magdeburg, Germany; Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany; Microbiology, Anhalt University of Applied Sciences, Bernburger Straße 55, 06354, Köthen, Germany
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium
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Kremp F, Müller V. Methanol and methyl group conversion in acetogenic bacteria: biochemistry, physiology and application. FEMS Microbiol Rev 2021; 45:5903270. [PMID: 32901799 DOI: 10.1093/femsre/fuaa040] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/29/2020] [Indexed: 12/24/2022] Open
Abstract
The production of bulk chemicals mostly depends on exhausting petroleum sources and leads to emission of greenhouse gases. Within the last decades the urgent need for alternative sources has increased and the development of bio-based processes received new attention. To avoid the competition between the use of sugars as food or fuel, other feedstocks with high availability and low cost are needed, which brought acetogenic bacteria into focus. This group of anaerobic organisms uses mixtures of CO2, CO and H2 for the production of mostly acetate and ethanol. Also methanol, a cheap and abundant bulk chemical produced from methane, is a suitable substrate for acetogenic bacteria. In methylotrophic acetogens the methyl group is transferred to the Wood-Ljungdahl pathway, a pathway to reduce CO2 to acetate via a series of C1-intermediates bound to tetrahydrofolic acid. Here we describe the biochemistry and bioenergetics of methanol conversion in the biotechnologically interesting group of anaerobic, acetogenic bacteria. Further, the bioenergetics of biochemical production from methanol is discussed.
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Affiliation(s)
- Florian Kremp
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Volker Müller
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
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Two Marine Desulfotomaculum spp. of Different Origin are Capable of Utilizing Acetone and Higher Ketones. Curr Microbiol 2021; 78:1763-1770. [PMID: 33751185 PMCID: PMC8084838 DOI: 10.1007/s00284-021-02441-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 03/01/2021] [Indexed: 11/06/2022]
Abstract
Degradation of acetone and higher ketones has been described in detail for aerobic and nitrate-reducing bacteria. Among sulfate-reducing bacteria, degradation of acetone and other ketones is still an uncommon ability and has not been understood completely yet. In the present work, we show that Desulfotomaculum arcticum and Desulfotomaculum geothermicum are able to degrade acetone and butanone. Total proteomics of cell-free extracts of both organisms indicated an involvement of a thiamine diphosphate-dependent enzyme, a B12-dependent mutase, and a specific dehydrogenase during acetone degradation. Similar enzymes were recently described to be involved in acetone degradation by Desulfococcus biacutus. As there are so far only two described sulfate reducers able to degrade acetone, D. arcticum and D. geothermicum represent two further species with this capacity. All these bacteria appear to degrade acetone via the same set of enzymes and therefore via the same pathway.
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Frey J, Kaßner S, Spiteller D, Mergelsberg M, Boll M, Schleheck D, Schink B. Activation of short-chain ketones and isopropanol in sulfate-reducing bacteria. BMC Microbiol 2021; 21:50. [PMID: 33593288 PMCID: PMC7888143 DOI: 10.1186/s12866-021-02112-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/29/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Degradation of acetone by aerobic and nitrate-reducing bacteria can proceed via carboxylation to acetoacetate and subsequent thiolytic cleavage to two acetyl residues. A different strategy was identified in the sulfate-reducing bacterium Desulfococcus biacutus that involves formylation of acetone to 2-hydroxyisobutyryl-CoA. RESULTS Utilization of short-chain ketones (acetone, butanone, 2-pentanone and 3-pentanone) and isopropanol by the sulfate reducer Desulfosarcina cetonica was investigated by differential proteome analyses and enzyme assays. Two-dimensional protein gel electrophoresis indicated that D. cetonica during growth with acetone expresses enzymes homologous to those described for Desulfococcus biacutus: a thiamine diphosphate (TDP)-requiring enzyme, two subunits of a B12-dependent mutase, and a NAD+-dependent dehydrogenase. Total proteomics of cell-free extracts confirmed these results and identified several additional ketone-inducible proteins. Acetone is activated, most likely mediated by the TDP-dependent enzyme, to a branched-chain CoA-ester, 2-hydroxyisobutyryl-CoA. This compound is linearized to 3-hydroxybutyryl-CoA by a coenzyme B12-dependent mutase followed by oxidation to acetoacetyl-CoA by a dehydrogenase. Proteomic analysis of isopropanol- and butanone-grown cells revealed the expression of a set of enzymes identical to that expressed during growth with acetone. Enzyme assays with cell-free extract of isopropanol- and butanone-grown cells support a B12-dependent isomerization. After growth with 2-pentanone or 3-pentanone, similar protein patterns were observed in cell-free extracts as those found after growth with acetone. CONCLUSIONS According to these results, butanone and isopropanol, as well as the two pentanone isomers, are degraded by the same enzymes that are used also in acetone degradation. Our results indicate that the degradation of several short-chain ketones appears to be initiated by TDP-dependent formylation in sulfate-reducing bacteria.
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Affiliation(s)
- Jasmin Frey
- Department of Biology, University of Konstanz, 78457, Constance, Germany
| | - Sophie Kaßner
- Department of Biology, University of Konstanz, 78457, Constance, Germany
| | - Dieter Spiteller
- Department of Biology, University of Konstanz, 78457, Constance, Germany
| | - Mario Mergelsberg
- Institute of Biology, Albert-Ludwigs-Universität, Freiburg, 79104, Freiburg, Germany
| | - Matthias Boll
- Institute of Biology, Albert-Ludwigs-Universität, Freiburg, 79104, Freiburg, Germany
| | - David Schleheck
- Department of Biology, University of Konstanz, 78457, Constance, Germany
| | - Bernhard Schink
- Department of Biology, University of Konstanz, 78457, Constance, Germany.
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Lee SY, Oh YK, Lee S, Fitriana HN, Moon M, Kim MS, Lee J, Min K, Park GW, Lee JP, Lee JS. Recent developments and key barriers to microbial CO 2 electrobiorefinery. BIORESOURCE TECHNOLOGY 2021; 320:124350. [PMID: 33186841 DOI: 10.1016/j.biortech.2020.124350] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/25/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
The electrochemical conversion of CO2 can include renewable surplus electricity storage and CO2 utilisation. This review focuses on the microbial CO2 electrobiorefinery based on microbial electrosynthesis (MES) which merges electrochemical and microbial conversion to produce biofuels and higher-value chemicals. In this review, recent developments are discussed about bioelectrochemical conversion of CO2 into biofuels and chemicals in MES via microbial CO2-fixation and electricity utilisation reactions. In addition, this review examines technical approaches to overcome the current limitations of MES including the following: engineering of the biocathode, application of electron mediators, and reactor optimisation, among others. An in-depth discussion of strategies for the CO2 electrobiorefinery is presented, including the integration of the biocathode with inorganic catalysts, screening of novel electroactive microorganisms, and metabolic engineering to improve target productivity from CO2.
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Affiliation(s)
- Soo Youn Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - You-Kwan Oh
- School of Chemical & Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Sangmin Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Hana Nur Fitriana
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea; Renewable Energy Engineering Department, Korea Institute of Energy Research Campus, University of Science and Technology, Daejeon 34113, South Korea
| | - Myounghoon Moon
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Min-Sik Kim
- Energy Resources Upcycling Research Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Jiye Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Kyoungseon Min
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Gwon Woo Park
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Joon-Pyo Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Jin-Suk Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea.
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Katsyv A, Müller V. Overcoming Energetic Barriers in Acetogenic C1 Conversion. Front Bioeng Biotechnol 2020; 8:621166. [PMID: 33425882 PMCID: PMC7793690 DOI: 10.3389/fbioe.2020.621166] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 11/19/2020] [Indexed: 11/13/2022] Open
Abstract
Currently one of the biggest challenges for society is to combat global warming. A solution to this global threat is the implementation of a CO2-based bioeconomy and a H2-based bioenergy economy. Anaerobic lithotrophic bacteria such as the acetogenic bacteria are key players in the global carbon and H2 cycle and thus prime candidates as driving forces in a H2- and CO2-bioeconomy. Naturally, they convert two molecules of CO2via the Wood-Ljungdahl pathway (WLP) to one molecule of acetyl-CoA which can be converted to different C2-products (acetate or ethanol) or elongated to C4 (butyrate) or C5-products (caproate). Since there is no net ATP generation from acetate formation, an electron-transport phosphorylation (ETP) module is hooked up to the WLP. ETP provides the cell with additional ATP, but the ATP gain is very low, only a fraction of an ATP per mol of acetate. Since acetogens live at the thermodynamic edge of life, metabolic engineering to obtain high-value products is currently limited by the low energy status of the cells that allows for the production of only a few compounds with rather low specificity. To set the stage for acetogens as production platforms for a wide range of bioproducts from CO2, the energetic barriers have to be overcome. This review summarizes the pathway, the energetics of the pathway and describes ways to overcome energetic barriers in acetogenic C1 conversion.
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Affiliation(s)
- Alexander Katsyv
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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Yan M, Treu L, Zhu X, Tian H, Basile A, Fotidis IA, Campanaro S, Angelidaki I. Insights into Ammonia Adaptation and Methanogenic Precursor Oxidation by Genome-Centric Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:12568-12582. [PMID: 32852203 PMCID: PMC8154354 DOI: 10.1021/acs.est.0c01945] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 08/22/2020] [Accepted: 08/27/2020] [Indexed: 05/04/2023]
Abstract
Ammonia released from the degradation of protein and/or urea usually leads to suboptimal anaerobic digestion (AD) when N-rich organic waste is used. However, the insights behind the differential ammonia tolerance of anaerobic microbiomes remain an enigma. In this study, the cultivation in synthetic medium with different carbon sources (acetate, methanol, formate, and H2/CO2) shaped a common initial inoculum into four unique ammonia-tolerant syntrophic populations. Specifically, various levels of ammonia tolerance were observed: consortia fed with methanol and H2/CO2 could grow at ammonia levels up to 7.25 g NH+-N/L, whereas the other two groups (formate and acetate) only thrived at 5.25 and 4.25 g NH+-N/L, respectively. Metabolic reconstruction highlighted that this divergent microbiome might be achieved by complementary metabolisms to maximize biomethane recovery from carbon sources, thus indicating the importance of the syntrophic community in the AD of N-rich substrates. Besides, sodium/proton antiporter operon, osmoprotectant/K+ regulator, and osmoprotectant synthesis operon may function as the main drivers of adaptation to the ammonia stress. Moreover, energy from the substrate-level phosphorylation and multiple energy-converting hydrogenases (e.g., Ech and Eha) could aid methanogens to balance the energy request for anabolic activities and contribute to thriving when exposed to high ammonia levels.
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Affiliation(s)
- Miao Yan
- Department of Environmental
Engineering, Technical University of Denmark, Bygningstorvet Bygning 115, DK-2800 Kongens Lyngby, Denmark
| | - Laura Treu
- Department of Biology, University
of Padova, Via U. Bassi
58/b, 35121 Padova, Italy
| | - Xinyu Zhu
- Department of Environmental
Engineering, Technical University of Denmark, Bygningstorvet Bygning 115, DK-2800 Kongens Lyngby, Denmark
| | - Hailin Tian
- Department of Environmental
Engineering, Technical University of Denmark, Bygningstorvet Bygning 115, DK-2800 Kongens Lyngby, Denmark
- NUS Environmental Research Institute, National
University of Singapore, 1 Create Way, 138602, Singapore
| | - Arianna Basile
- Department of Biology, University
of Padova, Via U. Bassi
58/b, 35121 Padova, Italy
| | - Ioannis A. Fotidis
- Department of Environmental
Engineering, Technical University of Denmark, Bygningstorvet Bygning 115, DK-2800 Kongens Lyngby, Denmark
- School of Civil Engineering, Southeast University, 210096 Nanjing, China
| | - Stefano Campanaro
- Department of Biology, University
of Padova, Via U. Bassi
58/b, 35121 Padova, Italy
- CRIBI Biotechnology Center, University of Padua, 35131 Padua, Italy
| | - Irini Angelidaki
- Department of Environmental
Engineering, Technical University of Denmark, Bygningstorvet Bygning 115, DK-2800 Kongens Lyngby, Denmark
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Abstract
Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl-CoA and ultimately acetate using the Wood-Ljungdahl pathway (WLP). This autotrophic metabolism plays a major role in the global carbon cycle and, if harnessed, can help reduce greenhouse gas emissions. Overall, the data presented here provide a framework for examining the ecology and evolution of the Acetobacterium genus and highlight the potential of these species as a source for production of fuels and chemicals from CO2 feedstocks. Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl coenzyme A (acetyl-CoA) and ultimately acetate using the Wood-Ljungdahl pathway (WLP). Acetobacterium woodii is the type strain of the Acetobacterium genus and has been critical for understanding the biochemistry and energy conservation in acetogens. Members of the Acetobacterium genus have been isolated from a variety of environments or have had genomes recovered from metagenome data, but no systematic investigation has been done on the unique and various metabolisms of the genus. To gain a better appreciation for the metabolic breadth of the genus, we sequenced the genomes of 4 isolates (A. fimetarium, A. malicum, A. paludosum, and A. tundrae) and conducted a comparative genome analysis (pan-genome) of 11 different Acetobacterium genomes. A unifying feature of the Acetobacterium genus is the carbon-fixing WLP. The methyl (cluster II) and carbonyl (cluster III) branches of the Wood-Ljungdahl pathway are highly conserved across all sequenced Acetobacterium genomes, but cluster I encoding the formate dehydrogenase is not. In contrast to A. woodii, all but four strains encode two distinct Rnf clusters, Rnf being the primary respiratory enzyme complex. Metabolism of fructose, lactate, and H2:CO2 was conserved across the genus, but metabolism of ethanol, methanol, caffeate, and 2,3-butanediol varied. Additionally, clade-specific metabolic potential was observed, such as amino acid transport and metabolism in the psychrophilic species, and biofilm formation in the A. wieringae clade, which may afford these groups an advantage in low-temperature growth or attachment to solid surfaces, respectively. IMPORTANCE Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl-CoA and ultimately acetate using the Wood-Ljungdahl pathway (WLP). This autotrophic metabolism plays a major role in the global carbon cycle and, if harnessed, can help reduce greenhouse gas emissions. Overall, the data presented here provide a framework for examining the ecology and evolution of the Acetobacterium genus and highlight the potential of these species as a source for production of fuels and chemicals from CO2 feedstocks.
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Dyksma S, Jansen L, Gallert C. Syntrophic acetate oxidation replaces acetoclastic methanogenesis during thermophilic digestion of biowaste. MICROBIOME 2020; 8:105. [PMID: 32620171 PMCID: PMC7334858 DOI: 10.1186/s40168-020-00862-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/11/2020] [Indexed: 05/19/2023]
Abstract
BACKGROUND Anaerobic digestion (AD) is a globally important technology for effective waste and wastewater management. In AD, microorganisms interact in a complex food web for the production of biogas. Here, acetoclastic methanogens and syntrophic acetate-oxidizing bacteria (SAOB) compete for acetate, a major intermediate in the mineralization of organic matter. Although evidence is emerging that syntrophic acetate oxidation is an important pathway for methane production, knowledge about the SAOB is still very limited. RESULTS A metabolic reconstruction of metagenome-assembled genomes (MAGs) from a thermophilic solid state biowaste digester covered the basic functions of the biogas microbial community. Firmicutes was the most abundant phylum in the metagenome (53%) harboring species that take place in various functions ranging from the hydrolysis of polymers to syntrophic acetate oxidation. The Wood-Ljungdahl pathway for syntrophic acetate oxidation and corresponding genes for energy conservation were identified in a Dethiobacteraceae MAG that is phylogenetically related to known SAOB. 16S rRNA gene amplicon sequencing and enrichment cultivation consistently identified the uncultured Dethiobacteraceae together with Syntrophaceticus, Tepidanaerobacter, and unclassified Clostridia as members of a potential acetate-oxidizing core community in nine full-scare digesters, whereas acetoclastic methanogens were barely detected. CONCLUSIONS Results presented here provide new insights into a remarkable anaerobic digestion ecosystem where acetate catabolism is mainly realized by Bacteria. Metagenomics and enrichment cultivation revealed a core community of diverse and novel uncultured acetate-oxidizing bacteria and point to a particular niche for them in dry fermentation of biowaste. Their genomic repertoire suggests metabolic plasticity besides the potential for syntrophic acetate oxidation. Video Abstract.
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Affiliation(s)
- Stefan Dyksma
- Faculty of Technology, Microbiology - Biotechnology, University of Applied Sciences Emden/Leer, Emden, Germany.
| | - Lukas Jansen
- Faculty of Technology, Microbiology - Biotechnology, University of Applied Sciences Emden/Leer, Emden, Germany
| | - Claudia Gallert
- Faculty of Technology, Microbiology - Biotechnology, University of Applied Sciences Emden/Leer, Emden, Germany
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Monomeric NADH-Oxidizing Methylenetetrahydrofolate Reductases from Mycobacterium smegmatis Lack Flavin Coenzyme. J Bacteriol 2020; 202:JB.00709-19. [PMID: 32253341 DOI: 10.1128/jb.00709-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/27/2020] [Indexed: 01/16/2023] Open
Abstract
5,10-Methylenetetrahydrofolate reductase (MetF/MTHFR) is an essential enzyme in one-carbon metabolism for de novo biosynthesis of methionine. Our in vivo and in vitro analyses of MSMEG_6664/MSMEI_6484, annotated as putative MTHFR in Mycobacterium smegmatis, failed to reveal their function as MTHFRs. However, we identified two hypothetical proteins, MSMEG_6596 and MSMEG_6649, as noncanonical MTHFRs in the bacterium. MTHFRs are known to be oligomeric flavoproteins. Both MSMEG_6596 and MSMEG_6649 are monomeric proteins and lack flavin coenzymes. In vitro, the catalytic efficiency (k cat/Km ) of MSMEG_6596 (MTHFR1) for 5,10-CH2-THF and NADH was ∼13.5- and 15.3-fold higher than that of MSMEG_6649 (MTHFR2). Thus, MSMEG_6596 is the major MTHFR. This interpretation was further supported by better rescue of the E. coli Δmthfr strain by MTHFR1 than by MTHFR2. As identified by liquid chromatography-tandem mass spectrometry, the product of MTHFR1- or MTHFR2-catalyzed reactions was 5-CH3-THF. The M. smegmatis Δmsmeg_6596 strain was partially auxotrophic for methionine and grew only poorly without methionine or without being complemented with a functional copy of MTHFR1 or MTHFR2. Furthermore, the Δmsmeg_6596 strain was more sensitive to folate pathway inhibitors (sulfachloropyridazine, p-aminosalicylic acid, sulfamethoxazole, and trimethoprim). The studies reveal that MTHFR1 and MTHFR2 are two noncanonical MTHFR proteins that are monomeric and lack flavin coenzyme. Both MTHFR1 and MTHFR2 are involved in de novo methionine biosynthesis and required for antifolate resistance in mycobacteria.IMPORTANCE MTHFR/MetF is an essential enzyme in a one-carbon metabolic pathway for de novo biosynthesis of methionine. MTHFRs are known to be oligomeric flavoproteins. Our in vivo and in vitro analyses of Mycobacterium smegmatis MSMEG_6664/MSMEI_6484, annotated as putative MTHFR, failed to reveal their function as MTHFRs. However, we identified two of the hypothetical proteins, MSMEG_6596 and MSMEG_6649, as MTHFR1 and MTHFR2, respectively. Interestingly, both MTHFRs are monomeric and lack flavin coenzymes. M. smegmatis deleted for the major mthfr (mthfr1) was partially auxotroph for methionine and more sensitive to folate pathway inhibitors (sulfachloropyridazine, para-aminosalicylic acid, sulfamethoxazole, and trimethoprim). The studies reveal that MTHFR1 and MTHFR2 are novel MTHFRs involved in de novo methionine biosynthesis and required for antifolate resistance in mycobacteria.
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Keller A, Schink B, Müller N. Energy-Conserving Enzyme Systems Active During Syntrophic Acetate Oxidation in the Thermophilic Bacterium Thermacetogenium phaeum. Front Microbiol 2019; 10:2785. [PMID: 31849917 PMCID: PMC6895022 DOI: 10.3389/fmicb.2019.02785] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/15/2019] [Indexed: 11/13/2022] Open
Abstract
The thermophilic acetogen Thermacetogenium phaeum uses the Wood-Ljungdahl pathway (WLP) in both directions, either for the production of acetate from various compounds or for the oxidation of acetate in syntrophic cooperation with methanogens. In this study, energy-conserving enzyme systems in T. phaeum were investigated in both metabolic directions. A gene cluster containing a membrane-bound periplasmically oriented formate dehydrogenase directly adjacent to putative menaquinone synthesis genes was identified in the genome. The protein products of these genes were identified by total proteome analysis, and menaquinone MK-7 had been found earlier as the dominant quinone in the membrane. Enzyme assays with membrane preparations and anthraquinone-2,6-disulfonate as electron acceptor verified the presence of a quinone-dependent formate dehydrogenase. A quinone-dependent methylene-THF reductase is active in the soluble fraction and in the membrane fraction. From these results we conclude a reversed electron transport system from methyl-THF oxidation to CO2 reduction yielding formate as reduced product which is transferred to the methanogenic partner. The redox potential difference between methyl-THF (Eo' = -200 mV) and formate (Eo' = -432 mV) does not allow electron transfer through syntrophic formate removal alone. We postulate that part of the ATP conserved by substrate-level phosphorylation has to be invested into the generation of a transmembrane proton gradient by ATPase. This proton gradient could drive the endergonic oxidation of methyl-THF in an enzyme reaction similar to the membrane-bound reversed electron transport system previously observed in the syntrophically butyrate-oxidizing bacterium Syntrophomonas wolfei. To balance the overall ATP budget in acetate oxidation, we postulate that acetate is activated through an ATP-independent path via aldehyde:ferredoxin oxidoreductase (AOR) and subsequent oxidation of acetaldehyde to acetyl-CoA.
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Affiliation(s)
- Anja Keller
- Department of Biology, Universität Konstanz, Konstanz, Germany.,Konstanz Research School Chemical Biology, Konstanz, Germany
| | - Bernhard Schink
- Department of Biology, Universität Konstanz, Konstanz, Germany.,Konstanz Research School Chemical Biology, Konstanz, Germany
| | - Nicolai Müller
- Department of Biology, Universität Konstanz, Konstanz, Germany
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