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Böer T, Engelhardt L, Lüschen A, Eysell L, Yoshida H, Schneider D, Angenent LT, Basen M, Daniel R, Poehlein A. Isolation and characterization of novel acetogenic Moorella strains for employment as potential thermophilic biocatalysts. FEMS Microbiol Ecol 2024; 100:fiae109. [PMID: 39118367 PMCID: PMC11328732 DOI: 10.1093/femsec/fiae109] [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: 03/25/2024] [Revised: 06/05/2024] [Accepted: 08/07/2024] [Indexed: 08/10/2024] Open
Abstract
Thermophilic acetogenic bacteria have attracted attention as promising candidates for biotechnological applications such as syngas fermentation, microbial electrosynthesis, and methanol conversion. Here, we aimed to isolate and characterize novel thermophilic acetogens from diverse environments. Enrichment of heterotrophic and autotrophic acetogens was monitored by 16S rRNA gene-based bacterial community analysis. Seven novel Moorella strains were isolated and characterized by genomic and physiological analyses. Two Moorella humiferrea isolates showed considerable differences during autotrophic growth. The M. humiferrea LNE isolate (DSM 117358) fermented carbon monoxide (CO) to acetate, while the M. humiferrea OCP isolate (DSM 117359) transformed CO to hydrogen and carbon dioxide (H2 + CO2), employing the water-gas shift reaction. Another carboxydotrophic hydrogenogenic Moorella strain was isolated from the covering soil of an active charcoal burning pile and proposed as the type strain (ACPsT) of the novel species Moorella carbonis (DSM 116161T and CCOS 2103T). The remaining four novel strains were affiliated with Moorella thermoacetica and showed, together with the type strain DSM 2955T, the production of small amounts of ethanol from H2 + CO2 in addition to acetate. The physiological analyses of the novel Moorella strains revealed isolate-specific differences that considerably increase the knowledge base on thermophilic acetogens for future applications.
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Affiliation(s)
- Tim Böer
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Lisa Engelhardt
- Microbiology, Institute of Biological Sciences, University Rostock, 18059 Rostock, Germany
| | - Alina Lüschen
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Lena Eysell
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Hiroki Yoshida
- Environmental Biotechnology Group, Department of Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Dominik Schneider
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Largus T Angenent
- Environmental Biotechnology Group, Department of Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Mirko Basen
- Microbiology, Institute of Biological Sciences, University Rostock, 18059 Rostock, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany
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Zhang JZ, Li YZ, Xi ZN, Gao HP, Zhang Q, Liu LC, Li FL, Ma XQ. Engineered acetogenic bacteria as microbial cell factory for diversified biochemicals. Front Bioeng Biotechnol 2024; 12:1395540. [PMID: 39055341 PMCID: PMC11269201 DOI: 10.3389/fbioe.2024.1395540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/28/2024] [Indexed: 07/27/2024] Open
Abstract
Acetogenic bacteria (acetogens) are a class of microorganisms with conserved Wood-Ljungdahl pathway that can utilize CO and CO2/H2 as carbon source for autotrophic growth and convert these substrates to acetate and ethanol. Acetogens have great potential for the sustainable production of biofuels and bulk biochemicals using C1 gases (CO and CO2) from industrial syngas and waste gases, which play an important role in achieving carbon neutrality. In recent years, with the development and improvement of gene editing methods, the metabolic engineering of acetogens is making rapid progress. With introduction of heterogeneous metabolic pathways, acetogens can improve the production capacity of native products or obtain the ability to synthesize non-native products. This paper reviews the recent application of metabolic engineering in acetogens. In addition, the challenges of metabolic engineering in acetogens are indicated, and strategies to address these challenges are also discussed.
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Affiliation(s)
- Jun-Zhe Zhang
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu-Zhen Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhi-Ning Xi
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Hui-Peng Gao
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Quan Zhang
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Li-Cheng Liu
- Key Laboratory of Marine Chemistry Theory and Technology (Ministry of Education), College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China
| | - Fu-Li Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Shandong Energy Institute, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
| | - Xiao-Qing Ma
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
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Moon J, Poehlein A, Daniel R, Müller V. Redirecting electron flow in Acetobacterium woodii enables growth on CO and improves growth on formate. Nat Commun 2024; 15:5424. [PMID: 38926344 PMCID: PMC11208171 DOI: 10.1038/s41467-024-49680-5] [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: 01/04/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
Anaerobic, acetogenic bacteria are well known for their ability to convert various one-carbon compounds, promising feedstocks for a future, sustainable biotechnology, to products such as acetate and biofuels. The model acetogen Acetobacterium woodii can grow on CO2, formate or methanol, but not on carbon monoxide, an important industrial waste product. Since hydrogenases are targets of CO inhibition, here, we genetically delete the two [FeFe] hydrogenases HydA2 and HydBA in A. woodii. We show that the ∆hydBA/hydA2 mutant indeed grows on CO and produces acetate, but only after a long adaptation period. SNP analyzes of CO-adapted cells reveal a mutation in the HycB2 subunit of the HydA2/HydB2/HydB3/Fdh-containing hydrogen-dependent CO2 reductase (HDCR). We observe an increase in ferredoxin-dependent CO2 reduction and vice versa by the HDCR in the absence of the HydA2 module and speculate that this is caused by the mutation in HycB2. In addition, the CO-adapted ∆hydBA/hydA2 mutant growing on formate has a final biomass twice of that of the wild type.
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Affiliation(s)
- Jimyung Moon
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue Str. 9, Frankfurt, Germany
| | - Anja Poehlein
- Göttingen Genomics Laboratory, Institute for Microbiology and Genetics, Georg August University, Grisebachstr. 8, Göttingen, Germany
| | - Rolf Daniel
- Göttingen Genomics Laboratory, Institute for Microbiology and Genetics, Georg August University, Grisebachstr. 8, Göttingen, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue Str. 9, Frankfurt, Germany.
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Hackmann TJ. The vast landscape of carbohydrate fermentation in prokaryotes. FEMS Microbiol Rev 2024; 48:fuae016. [PMID: 38821505 PMCID: PMC11187502 DOI: 10.1093/femsre/fuae016] [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: 04/05/2024] [Revised: 05/23/2024] [Accepted: 05/29/2024] [Indexed: 06/02/2024] Open
Abstract
Fermentation is a type of metabolism carried out by organisms in environments without oxygen. Despite being studied for over 185 years, the diversity and complexity of this metabolism are just now becoming clear. Our review starts with the definition of fermentation, which has evolved over the years and which we help further refine. We then examine the range of organisms that carry out fermentation and their traits. Over one-fourth of all prokaryotes are fermentative, use more than 40 substrates, and release more than 50 metabolic end products. These insights come from studies analyzing records of thousands of organisms. Next, our review examines the complexity of fermentation at the biochemical level. We map out pathways of glucose fermentation in unprecedented detail, covering over 120 biochemical reactions. We also review recent studies coupling genomics and enzymology to reveal new pathways and enzymes. Our review concludes with practical applications for agriculture, human health, and industry. All these areas depend on fermentation and could be improved through manipulating fermentative microbes and enzymes. We discuss potential approaches for manipulation, including genetic engineering, electrofermentation, probiotics, and enzyme inhibitors. We hope our review underscores the importance of fermentation research and stimulates the next 185 years of study.
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Affiliation(s)
- Timothy J Hackmann
- Department of Animal Science, University of California, Davis, CA 95616, United States
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Baum C, Zeldes B, Poehlein A, Daniel R, Müller V, Basen M. The energy-converting hydrogenase Ech2 is important for the growth of the thermophilic acetogen Thermoanaerobacter kivui on ferredoxin-dependent substrates. Microbiol Spectr 2024; 12:e0338023. [PMID: 38385688 PMCID: PMC10986591 DOI: 10.1128/spectrum.03380-23] [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: 09/15/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
Thermoanaerobacter kivui is the thermophilic acetogenic bacterium with the highest temperature optimum (66°C) and with high growth rates on hydrogen (H2) plus carbon dioxide (CO2). The bioenergetic model suggests that its redox and energy metabolism depends on energy-converting hydrogenases (Ech). Its genome encodes two Echs, Ech1 and Ech2, as sole coupling sites for energy conservation during growth on H2 + CO2. During growth on other substrates, its redox activity, the (proton-gradient-coupled) oxidation of H2 may be essential to provide reduced ferredoxin (Fd) to the cell. While Ech activity has been demonstrated biochemically, the physiological function of both Ech's is unclear. Toward that, we deleted the complete gene cluster encoding Ech2. Surprisingly, the ech2 mutant grew as fast as the wild type on sugar substrates and H2 + CO2. Hence, Ech1 may be the essential enzyme for energy conservation, and either Ech1 or another enzyme may substitute for H2-dependent Fd reduction during growth on sugar substrates, putatively the H2-dependent CO2 reductase (HDCR). Growth on pyruvate and CO, substrates that are oxidized by Fd-dependent enzymes, was significantly impaired, but to a different extent. While ∆ech2 grew well on pyruvate after four transfers, ∆ech2 did not adapt to CO. Cell suspensions of ∆ech2 converted pyruvate to acetate, but no acetate was produced from CO. We analyzed the genome of five T. kivui strains adapted to CO. Strikingly, all strains carried mutations in the hycB3 subunit of HDCR. These mutations are obviously essential for the growth on CO but may inhibit its ability to utilize Fd as substrate. IMPORTANCE Acetogens thrive by converting H2+CO2 to acetate. Under environmental conditions, this allows for only very little energy to be conserved (∆G'<-20 kJ mol-1). CO2 serves as a terminal electron acceptor in the ancient Wood-Ljungdahl pathway (WLP). Since the WLP is ATP neutral, energy conservation during growth on H2 + CO2 is dependent on the redox metabolism. Two types of acetogens can be distinguished, Rnf- and Ech-type. The function of both membrane-bound enzyme complexes is twofold-energy conversion and redox balancing. Ech couples the Fd-dependent reduction of protons to H2 to the formation of a proton gradient in the thermophilic bacterium Thermoanaerobacter kivui. This bacterium may be utilized in gas fermentation at high temperatures, due to very high conversion rates and the availability of genetic tools. The physiological function of an Ech hydrogenase in T. kivui was studied to contribute an understanding of its energy and redox metabolism, a prerequisite for future industrial applications.
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Affiliation(s)
- Christoph Baum
- Microbiology, Institute for Biological Sciences, University of Rostock, Rostock, Germany
| | - Benjamin Zeldes
- Microbiology, Institute for Biological Sciences, University of Rostock, Rostock, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Georg-August University, Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Georg-August University, Göttingen, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Mirko Basen
- Microbiology, Institute for Biological Sciences, University of Rostock, Rostock, Germany
- Department of Maritime Systems, Interdisciplinary Faculty, University of Rostock, Rostock, Germany
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Hellmold N, Eberwein M, Phan MHT, Kümmel S, Einsle O, Deobald D, Adrian L. Dehalococcoides mccartyi strain CBDB1 takes up protons from the cytoplasm to reductively dehalogenate organohalides indicating a new modus of proton motive force generation. Front Microbiol 2023; 14:1305108. [PMID: 38192294 PMCID: PMC10772276 DOI: 10.3389/fmicb.2023.1305108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
Proton translocation across the cytoplasmic membrane is a vital process for all organisms. Dehalococcoides strains are strictly anaerobic organohalide respiring bacteria that lack quinones and cytochromes but express a large membrane-bound protein complex (OHR complex) proposed to generate a proton gradient. However, its functioning is unclear. By using a dehalogenase-based enzyme activity assay with deuterium-labelled water in various experimental designs, we obtained evidence that the halogen atom of the halogenated electron acceptor is substituted with a proton from the cytoplasm. This suggests that the protein complex couples exergonic electron flux through the periplasmic subunits of the OHR complex to the endergonic transport of protons from the cytoplasm across the cytoplasmic membrane against the proton gradient to the halogenated electron acceptor. Using computational tools, we located two proton-conducting half-channels in the AlphaFold2-predicted structure of the OmeB subunit of the OHR complex, converging in a highly conserved arginine residue that could play a proton gatekeeper role. The cytoplasmic proton half-channel in OmeB is connected to a putative proton-conducting path within the reductive dehalogenase subunit. Our results indicate that the reductive dehalogenase and its halogenated substrate serve as both electron and proton acceptors, providing insights into the proton translocation mechanism within the OHR complex and contributing to a better understanding of energy conservation in D. mccartyi strains. Our results reveal a very simple mode of energy conservation in anaerobic bacteria, showing that proton translocation coupled to periplasmic electron flow might have importance also in other microbial processes and biotechnological applications.
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Affiliation(s)
- Nadine Hellmold
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Marie Eberwein
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - My Hanh Thi Phan
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Steffen Kümmel
- Department Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Oliver Einsle
- Institute of Biochemistry, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
| | - Darja Deobald
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Lorenz Adrian
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
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Lehmann M, Prohaska C, Zeldes B, Poehlein A, Daniel R, Basen M. Adaptive laboratory evolution of a thermophile toward a reduced growth temperature optimum. Front Microbiol 2023; 14:1265216. [PMID: 37901835 PMCID: PMC10601643 DOI: 10.3389/fmicb.2023.1265216] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/14/2023] [Indexed: 10/31/2023] Open
Abstract
Thermophily is an ancient trait among microorganisms. The molecular principles to sustain high temperatures, however, are often described as adaptations, somewhat implying that they evolved from a non-thermophilic background and that thermophiles, i.e., organisms with growth temperature optima (TOPT) above 45°C, evolved from mesophilic organisms (TOPT 25-45°C). On the contrary, it has also been argued that LUCA, the last universal common ancestor of Bacteria and Archaea, may have been a thermophile, and mesophily is the derived trait. In this study, we took an experimental approach toward the evolution of a mesophile from a thermophile. We selected the acetogenic bacterium T. kivui (TOPT 66°C) since acetogenesis is considered ancient physiology and cultivated it at suboptimal low temperatures. We found that the lowest possible growth temperature (TMIN) under the chosen conditions was 39°C. The bacterium was subsequently subjected to adaptive laboratory evolution (ALE) by serial transfer at 45°C. Interestingly, after 67 transfers (approximately 180 generations), the adapted strain Adpt45_67 did not grow better at 45°C, but a shift in the TOPT to 60°C was observed. Growth at 45°C was accompanied by a change in the morphology as shorter, thicker cells were observed that partially occurred in chains. While the proportion of short-chain fatty acids increased at 50°C vs. 66°C in both strains, Adpt45_67 also showed a significantly increased proportion of plasmalogens. The genome analysis revealed 67 SNPs compared to the type strain, among these mutations in transcriptional regulators and in the cAMP binding protein. Ultimately, the molecular basis of the adaptation of T. kivui to a lower TOPT remains to be elucidated. The observed change in phenotype is the first experimental step toward the evolution of thermophiles growing at colder temperatures and toward a better understanding of the cold adaptation of thermophiles on early Earth.
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Affiliation(s)
- Maria Lehmann
- Department of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Christoph Prohaska
- Department of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Benjamin Zeldes
- Department of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Georg-August University, Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Georg-August University, Göttingen, Germany
| | - Mirko Basen
- Department of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
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Katsyv A, Essig M, Bedendi G, Sahin S, Milton RD, Müller V. Characterization of ferredoxins from the thermophilic, acetogenic bacterium Thermoanaerobacter kivui. FEBS J 2023; 290:4107-4125. [PMID: 37074156 DOI: 10.1111/febs.16801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/21/2023] [Accepted: 04/19/2023] [Indexed: 04/20/2023]
Abstract
A major electron carrier involved in energy and carbon metabolism in the acetogenic model organism Thermoanaerobacter kivui is ferredoxin, an iron-sulfur-containing, electron-transferring protein. Here, we show that the genome of T. kivui encodes four putative ferredoxin-like proteins (TKV_c09620, TKV_c16450, TKV_c10420 and TKV_c19530). All four genes were cloned, a His-tag encoding sequence was added and the proteins were produced from a plasmid in T. kivui. The purified proteins had an absorption peak at 430 nm typical for ferredoxins. The determined iron-sulfur content is consistent with the presence of two predicted [4Fe4S] clusters in TKV_c09620 and TKV_c19530 or one predicted [4Fe4S] cluster in TKV_c16450 and TKV_c10420 respectively. The reduction potential (Em ) for TKV_c09620, TKV_c16450, TKV_c10420 and TKV_c19530 was determined to be -386 ± 4 mV, -386 ± 2 mV, -559 ± 10 mV and -557 ± 3 mV, respectively. TKV_c09620 and TKV_c16450 served as electron carriers for different oxidoreductases from T. kivui. Deletion of the ferredoxin genes led to only a slight reduction of growth on pyruvate or autotrophically on H2 + CO2 . Transcriptional analysis revealed that TKV_c09620 was upregulated in a ΔTKV_c16450 mutant and vice versa TKV_c16450 in a ΔTKV_c09620 mutant, indicating that TKV_c09620 and TKV_c16450 can replace each other. In sum, our data are consistent with the hypothesis that TKV_c09620 and TKV_c16450 are ferredoxins involved in autotrophic and heterotrophic metabolism of T. kivui.
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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
| | - Melanie Essig
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Giada Bedendi
- Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, Switzerland
| | - Selmihan Sahin
- Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, Switzerland
| | - Ross D Milton
- Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva, Switzerland
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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Li W, Zhu L, Wu B, Liu Y, Li J, Xu L, Huangfu X, Shi D, Gu L, Chen C. Improving mesophilic anaerobic digestion of food waste by side-stream thermophilic reactor: Activation of methanogenic, key enzymes and metabolism. WATER RESEARCH 2023; 241:120167. [PMID: 37290195 DOI: 10.1016/j.watres.2023.120167] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 05/21/2023] [Accepted: 06/01/2023] [Indexed: 06/10/2023]
Abstract
Anaerobic digestion (AD) is a favorable way to convert organic pollutants, such as food waste (FW), into clean energy through microbial action. This work adopted a side-stream thermophilic anaerobic digestion (STA) strategy to improve a digestive system's efficiency and stability. Results showed that the STA strategy brought higher methane production as well as higher system stability. It quickly adapted to thermal stimulation and increased the specific methane production from 359 mL CH4/g·VS to 439 mL CH4/g·VS, which was also higher than 317 mL CH4/g·VS from single-stage thermophilic anaerobic digestion. Further exploration of the mechanism of STA using metagenomic and metaproteomic analysis revealed enhanced activity of key enzymes. The main metabolic pathway was up-regulated, while the dominant bacteria were concentrated, and the multifunctional Methanosarcina was enriched. These results indicate that STA optimized organic metabolism patterns, comprehensively promoted methane production pathways, and formed various energy conservation mechanisms. Further, the system's limited heating avoided adverse effects from thermal stimulation, and activated enzyme activity and heat shock proteins through circulating slurries, which improved the metabolic process, showing great application potential.
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Affiliation(s)
- Wen Li
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Lirong Zhu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Baocun Wu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Yongli Liu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Jinze Li
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Linji Xu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Xiaoliu Huangfu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Dezhi Shi
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
| | - Li Gu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China.
| | - Cong Chen
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing, 400045, PR China
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10
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Katsyv A, Kumar A, Saura P, Pöverlein MC, Freibert SA, T Stripp S, Jain S, Gamiz-Hernandez AP, Kaila VRI, Müller V, Schuller JM. Molecular Basis of the Electron Bifurcation Mechanism in the [FeFe]-Hydrogenase Complex HydABC. J Am Chem Soc 2023; 145:5696-5709. [PMID: 36811855 PMCID: PMC10021017 DOI: 10.1021/jacs.2c11683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Electron bifurcation is a fundamental energy coupling mechanism widespread in microorganisms that thrive under anoxic conditions. These organisms employ hydrogen to reduce CO2, but the molecular mechanisms have remained enigmatic. The key enzyme responsible for powering these thermodynamically challenging reactions is the electron-bifurcating [FeFe]-hydrogenase HydABC that reduces low-potential ferredoxins (Fd) by oxidizing hydrogen gas (H2). By combining single-particle cryo-electron microscopy (cryoEM) under catalytic turnover conditions with site-directed mutagenesis experiments, functional studies, infrared spectroscopy, and molecular simulations, we show that HydABC from the acetogenic bacteria Acetobacterium woodii and Thermoanaerobacter kivui employ a single flavin mononucleotide (FMN) cofactor to establish electron transfer pathways to the NAD(P)+ and Fd reduction sites by a mechanism that is fundamentally different from classical flavin-based electron bifurcation enzymes. By modulation of the NAD(P)+ binding affinity via reduction of a nearby iron-sulfur cluster, HydABC switches between the exergonic NAD(P)+ reduction and endergonic Fd reduction modes. Our combined findings suggest that the conformational dynamics establish a redox-driven kinetic gate that prevents the backflow of the electrons from the Fd reduction branch toward the FMN site, providing a basis for understanding general mechanistic principles of electron-bifurcating hydrogenases.
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Affiliation(s)
- Alexander Katsyv
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main 60438, Germany
| | - Anuj Kumar
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main 60438, Germany.,SYNMIKRO Research Center and Department of Chemistry, Philipps-University of Marburg, Marburg 35032, Germany
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Maximilian C Pöverlein
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Sven A Freibert
- Institut für Zytobiologie im Zentrum SYNMIKRO, Philipps-University of Marburg, Marburg 35032, Germany.,Core Facility "Protein Biochemistry and Spectroscopy", Marburg 35032, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin 14195, Germany
| | - Surbhi Jain
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main 60438, Germany
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main 60438, Germany
| | - Jan M Schuller
- SYNMIKRO Research Center and Department of Chemistry, Philipps-University of Marburg, Marburg 35032, Germany
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