51
|
Carbon fixation and energy metabolisms of a subseafloor olivine biofilm. ISME JOURNAL 2019; 13:1737-1749. [PMID: 30867546 DOI: 10.1038/s41396-019-0385-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 02/15/2019] [Accepted: 02/28/2019] [Indexed: 11/08/2022]
Abstract
Earth's largest aquifer ecosystem resides in igneous oceanic crust, where chemosynthesis and water-rock reactions provide the carbon and energy that support an active deep biosphere. The Calvin Cycle is the predominant carbon fixation pathway in cool, oxic, crust; however, the energy and carbon metabolisms in the deep thermal basaltic aquifer are poorly understood. Anaerobic carbon fixation pathways such as the Wood-Ljungdahl pathway, which uses hydrogen (H2) and CO2, may be common in thermal aquifers since water-rock reactions can produce H2 in hydrothermal environments and bicarbonate is abundant in seawater. To test this, we reconstructed the metabolisms of eleven bacterial and archaeal metagenome-assembled genomes from an olivine biofilm obtained from a Juan de Fuca Ridge basaltic aquifer. We found that the dominant carbon fixation pathway was the Wood-Ljungdahl pathway, which was present in seven of the eight bacterial genomes. Anaerobic respiration appears to be driven by sulfate reduction, and one bacterial genome contained a complete nitrogen fixation pathway. This study reveals the potential pathways for carbon and energy flux in the deep anoxic thermal aquifer ecosystem, and suggests that ancient H2-based chemolithoautotrophy, which once dominated Earth's early biosphere, may thus remain one of the dominant metabolisms in the suboceanic aquifer today.
Collapse
|
52
|
Porté H, Kougias PG, Alfaro N, Treu L, Campanaro S, Angelidaki I. Process performance and microbial community structure in thermophilic trickling biofilter reactors for biogas upgrading. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 655:529-538. [PMID: 30476832 DOI: 10.1016/j.scitotenv.2018.11.289] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/05/2018] [Accepted: 11/19/2018] [Indexed: 05/07/2023]
Abstract
This study evaluated the process performance and determined the microbial community structure of two lab-scale thermophilic trickling biofilter reactors used for biological methanation of hydrogen and carbon-dioxide for a total period of 94 days. Stable and robust operation was achieved by means of a single-pass gas flow. The quality of the output gas (>97%) was comparable to the methane purity achieved by commercial biogas upgrading systems fulfilling the specifications to be used as substitute to natural gas. The reactors' methane productivity reached >1.7 LCH4/(LR·d) at hydrogen loading rate of 7.2 LH2/(LR·d). The spatial distribution of the microbial consortia localized in the liquid media and biofilm enabled us to gain a deeper understanding on how the microbiome is structured inside the trickling biofilter. Sequencing results revealed a significant predominance of Methanothermobacter sp. in the biofilm. Unknown members of the class Clostridia were highly abundant in biofilm and liquid media, while acetate utilising bacteria predominated in liquid samples.
Collapse
Affiliation(s)
- Hugo Porté
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | - Panagiotis G Kougias
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
| | - Natalia Alfaro
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark; Institute of Sustainable Processes, Department of Chemical Engineering and Environmental Technology, Escuela de Ingenierías Industriales, Sede Dr. Mergelina, University of Valladolid, Dr. Mergelina s/n, 47011 Valladolid, Spain
| | - Laura Treu
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | | | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| |
Collapse
|
53
|
Neumann-Schaal M, Jahn D, Schmidt-Hohagen K. Metabolism the Difficile Way: The Key to the Success of the Pathogen Clostridioides difficile. Front Microbiol 2019; 10:219. [PMID: 30828322 PMCID: PMC6384274 DOI: 10.3389/fmicb.2019.00219] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 01/28/2019] [Indexed: 12/11/2022] Open
Abstract
Strains of Clostridioides difficile cause detrimental diarrheas with thousands of deaths worldwide. The infection process by the Gram-positive, strictly anaerobic gut bacterium is directly related to its unique metabolism, using multiple Stickland-type amino acid fermentation reactions coupled to Rnf complex-mediated sodium/proton gradient formation for ATP generation. Major pathways utilize phenylalanine, leucine, glycine and proline with the formation of 3-phenylproprionate, isocaproate, butyrate, 5-methylcaproate, valerate and 5-aminovalerate. In parallel a versatile sugar catabolism including pyruvate formate-lyase as a central enzyme and an incomplete tricarboxylic acid cycle to prevent unnecessary NADH formation completes the picture. However, a complex gene regulatory network that carefully mediates the continuous adaptation of this metabolism to changing environmental conditions is only partially elucidated. It involves the pleiotropic regulators CodY and SigH, the known carbon metabolism regulator CcpA, the proline regulator PrdR, the iron regulator Fur, the small regulatory RNA CsrA and potentially the NADH-responsive regulator Rex. Here, we describe the current knowledge of the metabolic principles of energy generation by C. difficile and the underlying gene regulatory scenarios.
Collapse
Affiliation(s)
- Meina Neumann-Schaal
- Leibniz Institute DSMZ, German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.,Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany
| | - Dieter Jahn
- Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany.,Institute of Microbiology, Braunschweig University of Technology, Braunschweig, Germany
| | - Kerstin Schmidt-Hohagen
- Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany.,Department of Bioinformatics and Biochemistry, Braunschweig University of Technology, Braunschweig, Germany
| |
Collapse
|
54
|
Hausmann B, Pelikan C, Rattei T, Loy A, Pester M. Long-Term Transcriptional Activity at Zero Growth of a Cosmopolitan Rare Biosphere Member. mBio 2019; 10:e02189-18. [PMID: 30755506 PMCID: PMC6372793 DOI: 10.1128/mbio.02189-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/04/2019] [Indexed: 01/05/2023] Open
Abstract
Microbial diversity in the environment is mainly concealed within the rare biosphere (all species with <0.1% relative abundance). While dormancy explains a low-abundance state very well, the mechanisms leading to rare but active microorganisms remain elusive. We used environmental systems biology to genomically and transcriptionally characterize "Candidatus Desulfosporosinus infrequens," a low-abundance sulfate-reducing microorganism cosmopolitan to freshwater wetlands, where it contributes to cryptic sulfur cycling. We obtained its near-complete genome by metagenomics of acidic peat soil. In addition, we analyzed anoxic peat soil incubated under in situ-like conditions for 50 days by Desulfosporosinus-targeted qPCR and metatranscriptomics. The Desulfosporosinus population stayed at a constant low abundance under all incubation conditions, averaging 1.2 × 106 16S rRNA gene copies per cm³ soil. In contrast, transcriptional activity of "Ca. Desulfosporosinus infrequens" increased at day 36 by 56- to 188-fold when minor amendments of acetate, propionate, lactate, or butyrate were provided with sulfate, compared to the no-substrate-control. Overall transcriptional activity was driven by expression of genes encoding ribosomal proteins, energy metabolism, and stress response but not by expression of genes encoding cell growth-associated processes. Since our results did not support growth of these highly active microorganisms in terms of biomass increase or cell division, they had to invest their sole energy for maintenance, most likely counterbalancing acidic pH conditions. This finding explains how a rare biosphere member can contribute to a biogeochemically relevant process while remaining in a zero-growth state over a period of 50 days.IMPORTANCE The microbial rare biosphere represents the largest pool of biodiversity on Earth and constitutes, in sum of all its members, a considerable part of a habitat's biomass. Dormancy or starvation is typically used to explain the persistence of low-abundance microorganisms in the environment. We show that a low-abundance microorganism can be highly transcriptionally active while remaining in a zero-growth state for at least 7 weeks. Our results provide evidence that this zero growth at a high cellular activity state is driven by maintenance requirements. We show that this is true for a microbial keystone species, in particular a cosmopolitan but permanently low-abundance sulfate-reducing microorganism in wetlands that is involved in counterbalancing greenhouse gas emissions. In summary, our results provide an important step forward in understanding time-resolved activities of rare biosphere members relevant for ecosystem functions.
Collapse
Affiliation(s)
- Bela Hausmann
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Claus Pelikan
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Thomas Rattei
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Computational Systems Biology, University of Vienna, Vienna, Austria
| | - Alexander Loy
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Michael Pester
- Department of Biology, University of Konstanz, Konstanz, Germany
- Department of Microorganisms, Leibniz Institute DSMZ, Braunschweig, Germany
- Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| |
Collapse
|
55
|
Abstract
Microbial adaptation to extreme conditions takes many forms, including specialized metabolism which may be crucial to survival in adverse conditions. Here, we analyze the diversity and environmental importance of systems allowing microbial carbon monoxide (CO) metabolism. CO is a toxic gas that can poison most organisms because of its tight binding to metalloproteins. Microbial CO uptake was first noted by Kluyver and Schnellen in 1947, and since then many microbes using CO via oxidation have emerged. Many strains use molecular oxygen as the electron acceptor for aerobic oxidation of CO using Mo-containing CO oxidoreductase enzymes named CO dehydrogenase. Anaerobic carboxydotrophs oxidize CO using CooS enzymes that contain Ni/Fe catalytic centers and are unrelated to CO dehydrogenase. Though rare on Earth in free form, CO is an important intermediate compound in anaerobic carbon cycling, as it can be coupled to acetogenesis, methanogenesis, hydrogenogenesis, and metal reduction. Many microbial species—both bacteria and archaea—have been shown to use CO to conserve energy or fix cell carbon or both. Microbial CO formation is also very common. Carboxydotrophs thus glean energy and fix carbon from a “metabolic leftover” that is not consumed by, and is toxic to, most microorganisms. Surprisingly, many species are able to thrive under culture headspaces sometimes exceeding 1 atmosphere of CO. It appears that carboxydotrophs are adapted to provide a metabolic “currency exchange” system in microbial communities in which CO arising either abiotically or biogenically is converted to CO
2 and H
2 that feed major metabolic pathways for energy conservation or carbon fixation. Solventogenic CO metabolism has been exploited to construct very large gas fermentation plants converting CO-rich industrial flue emissions into biofuels and chemical feedstocks, creating renewable energy while mitigating global warming. The use of thermostable CO dehydrogenase enzymes to construct sensitive CO gas sensors is also in progress.
Collapse
Affiliation(s)
- Frank T Robb
- Department of Microbiology and Immunology, and Inst of Marine and Environmental Technology, University of Maryland, Baltimore, Baltimore, MD, 21202, USA
| | - Stephen M Techtmann
- Department of Biological Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931, USA
| |
Collapse
|
56
|
Emerson DF, Woolston BM, Liu N, Donnelly M, Currie DH, Stephanopoulos G. Enhancing hydrogen-dependent growth of and carbon dioxide fixation by Clostridium ljungdahlii through nitrate supplementation. Biotechnol Bioeng 2018; 116:294-306. [PMID: 30267586 DOI: 10.1002/bit.26847] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/23/2018] [Accepted: 09/28/2018] [Indexed: 12/15/2022]
Abstract
Synthesis gas (syngas) fermentation via the Wood-Ljungdahl pathway is receiving growing attention as a possible platform for the fixation of CO 2 and renewable production of fuels and chemicals. However, the pathway operates near the thermodynamic limit of life, resulting in minimal adenosine triphosphate (ATP) production and long doubling times. This calls into question the feasibility of producing high-energy compounds at industrially relevant levels. In this study, we investigated the possibility of co-utilizing nitrate as an inexpensive additional electron acceptor to enhance ATP production during H 2 -dependent growth of Clostridium ljungdahlii, Moorella thermoacetica, and Acetobacterium woodii. In contrast to other acetogens tested, growth rate and final biomass titer were improved for C. ljungdahlii growing on a mixture of H 2 and CO 2 when supplemented with nitrate. Transcriptomic analysis, 13 CO 2 labeling, and an electron balance were used to understand how electron flux was partitioned between CO 2 and nitrate. We further show that, with nitrate supplementation, the ATP/adenosine diphosphate (ADP) ratio and acetyl-CoA pools were increased by fivefold and threefold, respectively, suggesting that this strategy could be useful for the production of ATP-intensive heterologous products from acetyl-CoA. Finally, we propose a pathway for enhanced ATP production from nitrate and use this as a basis to calculate theoretical yields for a variety of products. This study demonstrates a viable strategy for the decoupling of ATP production from carbon dioxide fixation, which will serve to significantly improve the CO 2 fixation rate and the production metrics of other chemicals from CO 2 and H 2 in this host.
Collapse
Affiliation(s)
- David F Emerson
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Benjamin M Woolston
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Nian Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Mackenzie Donnelly
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Devin H Currie
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| |
Collapse
|
57
|
Shin J, Song Y, Jin S, Lee JK, Kim DR, Kim SC, Cho S, Cho BK. Genome-scale analysis of Acetobacterium bakii reveals the cold adaptation of psychrotolerant acetogens by post-transcriptional regulation. RNA (NEW YORK, N.Y.) 2018; 24:1839-1855. [PMID: 30249742 PMCID: PMC6239172 DOI: 10.1261/rna.068239.118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 09/20/2018] [Indexed: 05/09/2023]
Abstract
Acetogens synthesize acetyl-CoA via CO2 or CO fixation, producing organic compounds. Despite their ecological and industrial importance, their transcriptional and post-transcriptional regulation has not been systematically studied. With completion of the genome sequence of Acetobacterium bakii (4.28-Mb), we measured changes in the transcriptome of this psychrotolerant acetogen in response to temperature variations under autotrophic and heterotrophic growth conditions. Unexpectedly, acetogenesis genes were highly up-regulated at low temperatures under heterotrophic, as well as autotrophic, growth conditions. To mechanistically understand the transcriptional regulation of acetogenesis genes via changes in RNA secondary structures of 5'-untranslated regions (5'-UTR), the primary transcriptome was experimentally determined, and 1379 transcription start sites (TSS) and 1100 5'-UTR were found. Interestingly, acetogenesis genes contained longer 5'-UTR with lower RNA-folding free energy than other genes, revealing that the 5'-UTRs control the RNA abundance of the acetogenesis genes under low temperature conditions. Our findings suggest that post-transcriptional regulation via RNA conformational changes of 5'-UTRs is necessary for cold-adaptive acetogenesis.
Collapse
Affiliation(s)
- Jongoh Shin
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Yoseb Song
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Sangrak Jin
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea
| | - Dong Rip Kim
- Department of Mechanical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Sun Chang Kim
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
- Intelligent Synthetic Biology Center, Daejeon 34141, Republic of Korea
| | - Suhyung Cho
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Byung-Kwan Cho
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
- Intelligent Synthetic Biology Center, Daejeon 34141, Republic of Korea
| |
Collapse
|
58
|
Song Y, Shin J, Jin S, Lee JK, Kim DR, Kim SC, Cho S, Cho BK. Genome-scale analysis of syngas fermenting acetogenic bacteria reveals the translational regulation for its autotrophic growth. BMC Genomics 2018; 19:837. [PMID: 30470174 PMCID: PMC6260860 DOI: 10.1186/s12864-018-5238-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 11/09/2018] [Indexed: 11/11/2022] Open
Abstract
Background Acetogenic bacteria constitute promising biocatalysts for the conversion of CO2/H2 or synthesis gas (H2/CO/CO2) into biofuels and value-added biochemicals. These microorganisms are naturally capable of autotrophic growth via unique acetogenesis metabolism. Despite their biosynthetic potential for commercial applications, a systemic understanding of the transcriptional and translational regulation of the acetogenesis metabolism remains unclear. Results By integrating genome-scale transcriptomic and translatomic data, we explored the regulatory logic of the acetogenesis to convert CO2 into biomass and metabolites in Eubacterium limosum. The results indicate that majority of genes associated with autotrophic growth including the Wood-Ljungdahl pathway, the reduction of electron carriers, the energy conservation system, and gluconeogenesis were transcriptionally upregulated. The translation efficiency of genes in cellular respiration and electron bifurcation was also highly enhanced. In contrast, the transcriptionally abundant genes involved in the carbonyl branch of the Wood-Ljungdahl pathway, as well as the ion-translocating complex and ATP synthase complex in the energy conservation system, showed decreased translation efficiency. The translation efficiencies of genes were regulated by 5′UTR secondary structure under the autotrophic growth condition. Conclusions The results illustrated that the acetogenic bacteria reallocate protein synthesis, focusing more on the translation of genes for the generation of reduced electron carriers via electron bifurcation, rather than on those for carbon metabolism under autotrophic growth. Electronic supplementary material The online version of this article (10.1186/s12864-018-5238-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yoseb Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Jongoh Shin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Sangrak Jin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Seoul, 05029, Republic of Korea
| | - Dong Rip Kim
- Department of Mechanical Engineering, Hanyang University, Seoul, 04763, Republic of Korea
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.,KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.,Intelligent Synthetic Biology Center, Daejeon, 34141, Republic of Korea
| | - Suhyung Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.,KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Byung-Kwan Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea. .,KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea. .,Intelligent Synthetic Biology Center, Daejeon, 34141, Republic of Korea.
| |
Collapse
|
59
|
Kremp F, Poehlein A, Daniel R, Müller V. Methanol metabolism in the acetogenic bacterium Acetobacterium woodii. Environ Microbiol 2018; 20:4369-4384. [PMID: 30003650 DOI: 10.1111/1462-2920.14356] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/07/2018] [Indexed: 11/29/2022]
Abstract
Methanol derived from plant tissue is ubiquitous in anaerobic sediments and a good substrate for anaerobes growing on C1 compounds such as methanogens and acetogens. In contrast to methanogens little is known about the physiology, biochemistry and bioenergetics of methanol utilization in acetogenic bacteria. To fill this gap, we have used the model acetogen Acetobacterium woodii to study methanol metabolism using physiological and biochemical experiments paired with molecular studies and transcriptome analysis. These studies identified the genes and enzymes involved in acetogenesis from methanol and the redox carriers involved. We will present the first comprehensive model for carbon and electron flow from methanol in an acetogen and the bioenergetics of acetogenesis from methanol.
Collapse
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
| | - Anja Poehlein
- Göttingen Genomics Laboratory, Institute for Microbiology and Genetics, Georg August University, Grisebachstr. 8, D-37077, Göttingen, Germany
| | - Rolf Daniel
- Göttingen Genomics Laboratory, Institute for Microbiology and Genetics, Georg August University, Grisebachstr. 8, D-37077, Göttingen, 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
| |
Collapse
|
60
|
Šafarič L, Shakeri Yekta S, Liu T, Svensson BH, Schnürer A, Bastviken D, Björn A. Dynamics of a Perturbed Microbial Community during Thermophilic Anaerobic Digestion of Chemically Defined Soluble Organic Compounds. Microorganisms 2018; 6:microorganisms6040105. [PMID: 30314333 PMCID: PMC6313639 DOI: 10.3390/microorganisms6040105] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/06/2018] [Accepted: 10/10/2018] [Indexed: 11/22/2022] Open
Abstract
Knowledge of microbial community dynamics in relation to process perturbations is fundamental to understand and deal with the instability of anaerobic digestion (AD) processes. This study aims to investigate the microbial community structure and function of a thermophilic AD process, fed with a chemically defined substrate, and its association with process performance stability. Next generation amplicon sequencing of 16S ribosomal RNA (rRNA) genes revealed that variations in relative abundances of the predominant bacterial species, Defluviitoga tunisiensis and Anaerobaculum hydrogeniformans, were not linked to the process performance stability, while dynamics of bacterial genera of low abundance, Coprothermobacter and Defluviitoga (other than D. tunisiensis), were associated with microbial community function and process stability. A decrease in the diversity of the archaeal community was observed in conjunction with process recovery and stable performance, implying that the high abundance of specific archaeal group(s) contributed to the stable AD. Dominance of hydrogenotrophic Methanoculleus particularly corresponded to an enhanced microbial acetate and propionate turnover capacity, whereas the prevalence of hydrogenotrophic Methanothermobacter and acetoclastic Methanosaeta was associated with instable AD. Acetate oxidation via syntrophic interactions between Coprothermobacter and Methanoculleus was potentially the main methane-formation pathway during the stable process. We observed that supplementation of Se and W to the medium improved the propionate turnover by the thermophilic consortium. The outcomes of our study provided insights into the community dynamics and trace element requirements in relation to the process performance stability of thermophilic AD.
Collapse
Affiliation(s)
- Luka Šafarič
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
- Biogas Research Center, Linköping University, 581 83 Linköping, Sweden.
| | - Sepehr Shakeri Yekta
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
- Biogas Research Center, Linköping University, 581 83 Linköping, Sweden.
| | - Tong Liu
- Department of Molecular Science, Swedish University of Agricultural Science, Uppsala BioCenter, 75007 Uppsala, Sweden.
| | - Bo H Svensson
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
- Biogas Research Center, Linköping University, 581 83 Linköping, Sweden.
| | - Anna Schnürer
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
- Biogas Research Center, Linköping University, 581 83 Linköping, Sweden.
- Department of Molecular Science, Swedish University of Agricultural Science, Uppsala BioCenter, 75007 Uppsala, Sweden.
| | - David Bastviken
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
| | - Annika Björn
- Department of Thematic Studies-Environmental Change, Linköping University, 581 83 Linköping, Sweden.
- Biogas Research Center, Linköping University, 581 83 Linköping, Sweden.
| |
Collapse
|
61
|
Xavier JC, Preiner M, Martin WF. Something special about CO-dependent CO 2 fixation. FEBS J 2018; 285:4181-4195. [PMID: 30240136 PMCID: PMC6282760 DOI: 10.1111/febs.14664] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/08/2018] [Accepted: 09/19/2018] [Indexed: 01/02/2023]
Abstract
Carbon dioxide enters metabolism via six known CO2 fixation pathways, of which only one is linear, exergonic in the direction of CO2‐assimilation, and present in both bacterial and archaeal anaerobes – the Wood‐Ljungdahl (WL) or reductive acetyl‐CoA pathway. Carbon monoxide (CO) plays a central role in the WL pathway as an energy rich intermediate. Here, we scan the major biochemical reaction databases for reactions involving CO and CO2. We identified 415 reactions corresponding to enzyme commission (EC) numbers involving CO2, which are non‐randomly distributed across different biochemical pathways. Their taxonomic distribution, reversibility under physiological conditions, cofactors and prosthetic groups are summarized. In contrast to CO2, only 15 reaction classes involving CO were detected. Closer inspection reveals that CO interfaces with metabolism and the carbon cycle at only two enzymes: anaerobic carbon monoxide dehydrogenase (CODH), a Ni‐ and Fe‐containing enzyme that generates CO for CO2 fixation in the WL pathway, and aerobic CODH, a Mo‐ and Cu‐containing enzyme that oxidizes environmental CO as an electron source. The CO‐dependent reaction of the WL pathway involves carbonyl insertion into a methyl carbon‐nickel at the Ni‐Fe‐S A‐cluster of acetyl‐CoA synthase (ACS). It appears that no alternative mechanisms to the CO‐dependent reaction of ACS have evolved in nearly 4 billion years, indicating an ancient and mechanistically essential role for CO at the onset of metabolism.
Collapse
Affiliation(s)
- Joana C Xavier
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany
| | - Martina Preiner
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany
| | - William F Martin
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany.,Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| |
Collapse
|
62
|
Treu L, Kougias PG, de Diego-Díaz B, Campanaro S, Bassani I, Fernández-Rodríguez J, Angelidaki I. Two-year microbial adaptation during hydrogen-mediated biogas upgrading process in a serial reactor configuration. BIORESOURCE TECHNOLOGY 2018; 264:140-147. [PMID: 29800774 DOI: 10.1016/j.biortech.2018.05.070] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 05/07/2023]
Abstract
Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift in the anaerobic digestion microbiome was expected and evaluated by 16S rRNA amplicon analysis. Results demonstrated that the most abundant archaeal species identified in the first time point, Candidatus Methanoculleus thermohydrogenotrophicum, was replaced by Methanothermobacter thermautotrophicus, becoming dominant after the community adaptation. The most interesting taxonomic units were clustered by relative abundance and six main long-term adaptation trends were found, characterizing functionally related microbes (e.g. homoacetogens).
Collapse
Affiliation(s)
- L Treu
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | - P G Kougias
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
| | - B de Diego-Díaz
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark; Department of Chemistry, University of Navarra, Spain
| | - S Campanaro
- Department of Biology, University of Padua, Via U. Bassi 58/b, 35131 Padova, Italy
| | - I Bassani
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| | | | - I Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark
| |
Collapse
|
63
|
Kadnikov VV, Mardanov AV, Beletsky AV, Banks D, Pimenov NV, Frank YA, Karnachuk OV, Ravin NV. A metagenomic window into the 2-km-deep terrestrial subsurface aquifer revealed multiple pathways of organic matter decomposition. FEMS Microbiol Ecol 2018; 94:5067867. [DOI: 10.1093/femsec/fiy152] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/06/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Vitaly V Kadnikov
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33-2, Moscow, 119071, Russia
| | - Andrey V Mardanov
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33-2, Moscow, 119071, Russia
| | - Alexey V Beletsky
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33-2, Moscow, 119071, Russia
| | - David Banks
- School of Engineering, Systems Power & Energy, Glasgow University, Glasgow G12 8QQ, and Holymoor Consultancy Ltd., 360 Ashgate Road, Chesterfield, Derbyshire S40 4BW, UK
| | - Nikolay V Pimenov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp 33-2, Moscow, 119071, Russia
| | - Yulia A Frank
- Laboratory of Biochemistry and Molecular Biology, Tomsk State University, Lenina prosp. 35, Tomsk, 634050, Russia
| | - Olga V Karnachuk
- Laboratory of Biochemistry and Molecular Biology, Tomsk State University, Lenina prosp. 35, Tomsk, 634050, Russia
| | - Nikolai V Ravin
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prosp. 33-2, Moscow, 119071, Russia
| |
Collapse
|
64
|
Toshchakov SV, Lebedinsky AV, Sokolova TG, Zavarzina DG, Korzhenkov AA, Teplyuk AV, Chistyakova NI, Rusakov VS, Bonch-Osmolovskaya EA, Kublanov IV, Gavrilov SN. Genomic Insights Into Energy Metabolism of Carboxydocella thermautotrophica Coupling Hydrogenogenic CO Oxidation With the Reduction of Fe(III) Minerals. Front Microbiol 2018; 9:1759. [PMID: 30123201 PMCID: PMC6085454 DOI: 10.3389/fmicb.2018.01759] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 07/13/2018] [Indexed: 01/17/2023] Open
Abstract
The genus Carboxydocella forms a deeply branching family in the class Clostridia and is currently represented by three physiologically diverse species of thermophilic prokaryotes. The type strain of the type species, Carboxydocella thermautotrophica 41T, is an obligate chemolithoautotroph growing exclusively by hydrogenogenic CO oxidation. Another strain, isolated from a hot spring at Uzon caldera, Kamchatka in the course of this work, is capable of coupling carboxydotrophy and dissimilatory reduction of Fe(III) from oxic and phyllosilicate minerals. The processes of carboxydotrophy and Fe(III) reduction appeared to be interdependent in this strain. The genomes of both isolates were sequenced, assembled into single chromosome sequences (for strain 41T a plasmid sequence was also assembled) and analyzed. Genome analysis revealed that each of the two strains possessed six genes encoding diverse Ni,Fe-containing CO dehydrogenases (maximum reported in complete prokaryotic genomes), indicating crucial role of carbon monoxide in C. thermautotrophica metabolism. Both strains possessed a set of 30 multiheme c-type cytochromes, but only the newly isolated Fe-reducing strain 019 had one extra gene of a 17-heme cytochrome, which is proposed to represent a novel determinant of dissimilatory iron reduction in prokaryotes. Mössbauer studies revealed that strain 019 induced reductive transformation of the abundant ferric/ferrous-mica mineral glauconite to siderite during carboxydotrophic growth. Reconstruction of the C. thermautotrophica strains energy metabolism is the first comprehensive genome analysis of a representative of the deep phylogenetic branch Clostridia Incertae Sedis, family V. Our data provide insights into energy metabolism of C. thermautotrophica with an emphasis on its ecological implications.
Collapse
Affiliation(s)
- Stepan V. Toshchakov
- Laboratory of Microbial Genomics, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Alexander V. Lebedinsky
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Tatyana G. Sokolova
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Daria G. Zavarzina
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Alexei A. Korzhenkov
- Laboratory of Microbial Genomics, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Alina V. Teplyuk
- Laboratory of Microbial Genomics, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | | | | | | | - Ilya V. Kublanov
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Sergey N. Gavrilov
- Winogradsky Institute of Microbiology, FRC Biotechnology, Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
65
|
Takors R, Kopf M, Mampel J, Bluemke W, Blombach B, Eikmanns B, Bengelsdorf FR, Weuster-Botz D, Dürre P. Using gas mixtures of CO, CO 2 and H 2 as microbial substrates: the do's and don'ts of successful technology transfer from laboratory to production scale. Microb Biotechnol 2018; 11:606-625. [PMID: 29761637 PMCID: PMC6011938 DOI: 10.1111/1751-7915.13270] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/26/2018] [Accepted: 03/28/2018] [Indexed: 01/26/2023] Open
Abstract
The reduction of CO2 emissions is a global effort which is not only supported by the society and politicians but also by the industry. Chemical producers worldwide follow the strategic goal to reduce CO2 emissions by replacing existing fossil-based production routes with sustainable alternatives. The smart use of CO and CO2 /H2 mixtures even allows to produce important chemical building blocks consuming the said gases as substrates in carboxydotrophic fermentations with acetogenic bacteria. However, existing industrial infrastructure and market demands impose constraints on microbes, bioprocesses and products that require careful consideration to ensure technical and economic success. The mini review provides scientific and industrial facets finally to enable the successful implementation of gas fermentation technologies in the industrial scale.
Collapse
Affiliation(s)
- Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Michael Kopf
- BASF SE, Bio-Process Development, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany
| | - Joerg Mampel
- BRAIN AG, Darmstädter Straße 34-36, 64673, Zwingenberg, Germany
| | - Wilfried Bluemke
- Evonik Technology and Infrastructure GmbH, Process Technology & Engineering, Rodenbacher Chaussee 4, 63457, Hanau-Wolfgang, Germany
| | - Bastian Blombach
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Bernhard Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Dirk Weuster-Botz
- Department of Mechanical Engineering, Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| |
Collapse
|
66
|
Draft Genome Sequence of Moorella sp. Strain Hama-1, a Novel Acetogenic Bacterium Isolated from a Thermophilic Digestion Reactor. GENOME ANNOUNCEMENTS 2018; 6:6/24/e00517-18. [PMID: 29903821 PMCID: PMC6003730 DOI: 10.1128/genomea.00517-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Moorella sp. strain Hama-1 was isolated from a thermophilic anaerobic digestion reactor treating poly(l-lactic acid). The strain is a thermophilic acetogen capable of lactate oxidation under anaerobic conditions. Here, we report the draft genome sequence of strain Hama-1, comprising 3.27 Mb in 48 contigs, with a G+C content of 56.6%.
Collapse
|
67
|
Functional Expression of the Clostridium ljungdahlii Acetyl-Coenzyme A Synthase in Clostridium acetobutylicum as Demonstrated by a Novel In Vivo CO Exchange Activity En Route to Heterologous Installation of a Functional Wood-Ljungdahl Pathway. Appl Environ Microbiol 2018; 84:AEM.02307-17. [PMID: 29374033 DOI: 10.1128/aem.02307-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/21/2018] [Indexed: 11/20/2022] Open
Abstract
Engineering the Wood-Ljungdahl pathway (WLP) in the established industrial organism Clostridium acetobutylicum would allow for the conversion of carbohydrates into butanol, acetone, and other metabolites at higher yields than are currently possible, while minimizing CO2 and H2 release. To this effect, we expressed 11 Clostridium ljungdahlii core genes coding for enzymes and accessory proteins of the WLP in Clostridium acetobutylicum The engineered WLP in C. acetobutylicum showed functionality of the eastern branch of the pathway based on the formation of labeled 5,10-methylenetetrahydrofolate from 13C-labeled formate, as well as functionality of the western branch as evidenced by the formation of CO from CO2 However, the lack of labeling in acetate and butyrate pools indicated that the connection between the two branches is not functional. The focus of our investigation then centered on the functional expression of the acetyl-coenzyme A (CoA) synthase (ACS), which forms a complex with the CO dehydrogenase (CODH) and serves to link the two branches of the WLP. The CODH/ACS complex catalyzes the reduction of CO2 to CO and the condensation of CO with a methyl group to form acetyl-CoA, respectively. Here, we show the simultaneous activities of the two recombinant enzymes. We demonstrate in vivo the classical in vitro ACS carbonyl carbon exchange assay, whereby the carbonyl carbon of acetyl-CoA is exchanged with the CO carbon. Our data suggest that the low heterologous expression of ACS may limit the functionality of the heterologous WLP in C. acetobutylicum IMPORTANCE The bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase (CODH/ACS) from C. ljungdahlii was heterologously expressed in the obligate heterotroph C. acetobutylicum The functional activity of the CODH was confirmed through both the oxidation and reduction of CO, as had previously been shown for the heterologous CODH from Clostridium carboxidivorans Significantly, a novel in vivo assay for ACS exchange activity using 13C-tracers was developed and used to confirm functional ACS expression.
Collapse
|
68
|
Mayer A, Weuster-Botz D. Reaction engineering analysis of the autotrophic energy metabolism of Clostridium aceticum. FEMS Microbiol Lett 2018; 364:4562590. [PMID: 29069379 DOI: 10.1093/femsle/fnx219] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/17/2017] [Indexed: 11/13/2022] Open
Abstract
Acetogenesis with CO2:H2 or CO via the reductive acetyl-CoA pathway does not provide any net ATP formation in homoacetogenic bacteria. Autotrophic energy conservation is coupled to the generation of chemiosmotic H+ or Na+ gradients across the cytoplasm membrane using either a ferredoxin:NAD+ oxidoreductase (Rnf), a ferredoxin:H+ oxidoreductase (Ech) or substrate-level phosphorylation via cytochromes. The first isolated acetogenic bacterium Clostridium aceticum shows both cytochromes and Rnf complex, putting it into an outstanding position. Autotrophic batch processes with continuous gas supply were performed in fully controlled stirred-tank bioreactors to elucidate energy metabolism of C. aceticum. Varying the initial Na+ concentration in the medium showed sodium-dependent growth of C. aceticum with a growth optimum between 60 and 90 mM Na+. The addition of the Na+-selective ionophore ETH2120 or the protonophore CCCP or the H+/cation-antiporter monensin revealed that an H+ gradient is used as primary energy conservation mechanism, which strengthens the exceptional position of C. aceticum as acetogenic bacterium showing an H+-dependent energy conservation mechanism as well as Na+-dependent growth.
Collapse
|
69
|
The deep-subsurface sulfate reducer Desulfotomaculum kuznetsovii employs two methanol-degrading pathways. Nat Commun 2018; 9:239. [PMID: 29339722 PMCID: PMC5770442 DOI: 10.1038/s41467-017-02518-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/06/2017] [Indexed: 11/08/2022] Open
Abstract
Methanol is generally metabolized through a pathway initiated by a cobalamine-containing methanol methyltransferase by anaerobic methylotrophs (such as methanogens and acetogens), or through oxidation to formaldehyde using a methanol dehydrogenase by aerobes. Methanol is an important substrate in deep-subsurface environments, where thermophilic sulfate-reducing bacteria of the genus Desulfotomaculum have key roles. Here, we study the methanol metabolism of Desulfotomaculum kuznetsovii strain 17T, isolated from a 3000-m deep geothermal water reservoir. We use proteomics to analyze cells grown with methanol and sulfate in the presence and absence of cobalt and vitamin B12. The results indicate the presence of two methanol-degrading pathways in D. kuznetsovii, a cobalt-dependent methanol methyltransferase and a cobalt-independent methanol dehydrogenase, which is further confirmed by stable isotope fractionation. This is the first report of a microorganism utilizing two distinct methanol conversion pathways. We hypothesize that this gives D. kuznetsovii a competitive advantage in its natural environment.
Collapse
|
70
|
Chen J, Daniell J, Griffin D, Li X, Henson MA. Experimental testing of a spatiotemporal metabolic model for carbon monoxide fermentation with Clostridium autoethanogenum. Biochem Eng J 2018. [DOI: 10.1016/j.bej.2017.10.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
71
|
Bengelsdorf FR, Beck MH, Erz C, Hoffmeister S, Karl MM, Riegler P, Wirth S, Poehlein A, Weuster-Botz D, Dürre P. Bacterial Anaerobic Synthesis Gas (Syngas) and CO 2+H 2 Fermentation. ADVANCES IN APPLIED MICROBIOLOGY 2018; 103:143-221. [PMID: 29914657 DOI: 10.1016/bs.aambs.2018.01.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Anaerobic bacterial gas fermentation gains broad interest in various scientific, social, and industrial fields. This microbial process is carried out by a specific group of bacterial strains called acetogens. All these strains employ the Wood-Ljungdahl pathway but they belong to different taxonomic groups. Here we provide an overview of the metabolism of acetogens and naturally occurring products. Characteristics of 61 strains were summarized and selected acetogens described in detail. Acetobacterium woodii, Clostridium ljungdahlii, and Moorella thermoacetica serve as model organisms. Results of approaches such as genome-scale modeling, proteomics, and transcriptomics are discussed. Metabolic engineering of acetogens can be used to expand the product portfolio to platform chemicals and to study different aspects of cell physiology. Moreover, the fermentation of gases requires specific reactor configurations and the development of the respective technology, which can be used for an industrial application. Even though the overall process will have a positive effect on climate, since waste and greenhouse gases could be converted into commodity chemicals, some legislative barriers exist, which hamper successful exploitation of this technology.
Collapse
Affiliation(s)
- Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany.
| | - Matthias H Beck
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Catarina Erz
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Sabrina Hoffmeister
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Michael M Karl
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Peter Riegler
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Steffen Wirth
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Dirk Weuster-Botz
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| |
Collapse
|
72
|
Homoacetogenesis in Deep-Sea Chloroflexi, as Inferred by Single-Cell Genomics, Provides a Link to Reductive Dehalogenation in Terrestrial Dehalococcoidetes. mBio 2017; 8:mBio.02022-17. [PMID: 29259088 PMCID: PMC5736913 DOI: 10.1128/mbio.02022-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylum Chloroflexi. In this report, we investigated genomes of single cells obtained from deep-sea sediments of the Peruvian Margin, which are enriched in such Chloroflexi. 16S rRNA gene sequence analysis placed two of these single-cell-derived genomes (DscP3 and Dsc4) in a clade of subphylum I Chloroflexi which were previously recovered from deep-sea sediment in the Okinawa Trough and a third (DscP2-2) as a member of the previously reported DscP2 population from Peruvian Margin site 1230. The presence of genes encoding enzymes of a complete Wood-Ljungdahl pathway, glycolysis/gluconeogenesis, a Rhodobacter nitrogen fixation (Rnf) complex, glyosyltransferases, and formate dehydrogenases in the single-cell genomes of DscP3 and Dsc4 and the presence of an NADH-dependent reduced ferredoxin:NADP oxidoreductase (Nfn) and Rnf in the genome of DscP2-2 imply a homoacetogenic lifestyle of these abundant marine Chloroflexi. We also report here the first complete pathway for anaerobic benzoate oxidation to acetyl coenzyme A (CoA) in the phylum Chloroflexi (DscP3 and Dsc4), including a class I benzoyl-CoA reductase. Of remarkable evolutionary significance, we discovered a gene encoding a formate dehydrogenase (FdnI) with reciprocal closest identity to the formate dehydrogenase-like protein (complex iron-sulfur molybdoenzyme [CISM], DET0187) of terrestrial Dehalococcoides/Dehalogenimonas spp. This formate dehydrogenase-like protein has been shown to lack formate dehydrogenase activity in Dehalococcoides/Dehalogenimonas spp. and is instead hypothesized to couple HupL hydrogenase to a reductive dehalogenase in the catabolic reductive dehalogenation pathway. This finding of a close functional homologue provides an important missing link for understanding the origin and the metabolic core of terrestrial Dehalococcoides/Dehalogenimonas spp. and of reductive dehalogenation, as well as the biology of abundant deep-sea Chloroflexi. The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylum Chloroflexi. In this report, we investigated genomes of single cells obtained from deep-sea sediments and provide evidence for a homacetogenic lifestyle of these abundant marine Chloroflexi. Moreover, genome signature and key metabolic genes indicate an evolutionary relationship between these deep-sea sediment microbes and terrestrial, reductively dehalogenating Dehalococcoides.
Collapse
|
73
|
Balancing cellular redox metabolism in microbial electrosynthesis and electro fermentation - A chance for metabolic engineering. Metab Eng 2017; 45:109-120. [PMID: 29229581 DOI: 10.1016/j.ymben.2017.12.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/15/2017] [Accepted: 12/06/2017] [Indexed: 01/05/2023]
Abstract
More and more microbes are discovered that are capable of extracellular electron transfer, a process in which they use external electrodes as electron donors or acceptors for metabolic reactions. This feature can be used to overcome cellular redox limitations and thus optimizing microbial production. The technologies, termed microbial electrosynthesis and electro-fermentation, have the potential to open novel bio-electro production platforms from sustainable energy and carbon sources. However, the performance of reported systems is currently limited by low electron transport rates between microbes and electrodes and our limited ability for targeted engineering of these systems due to remaining knowledge gaps about the underlying fundamental processes. Metabolic engineering offers many opportunities to optimize these processes, for instance by genetic engineering of pathways for electron transfer on the one hand and target product synthesis on the other hand. With this review, we summarize the status quo of knowledge and engineering attempts around chemical production in bio-electrochemical systems from a microbe perspective. Challenges associated with the introduction or enhancement of extracellular electron transfer capabilities into production hosts versus the engineering of target compound synthesis pathways in natural exoelectrogens are discussed. Recent advances of the research community in both directions are examined critically. Further, systems biology approaches, for instance using metabolic modelling, are examined for their potential to provide insight into fundamental processes and to identify targets for metabolic engineering.
Collapse
|
74
|
Overcoming the energetic limitations of syngas fermentation. Curr Opin Chem Biol 2017; 41:84-92. [DOI: 10.1016/j.cbpa.2017.10.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/28/2017] [Accepted: 10/03/2017] [Indexed: 01/05/2023]
|
75
|
Anaerobic degradation of 1-methylnaphthalene by a member of the Thermoanaerobacteraceae contained in an iron-reducing enrichment culture. Biodegradation 2017; 29:23-39. [PMID: 29177812 PMCID: PMC5773621 DOI: 10.1007/s10532-017-9811-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 11/02/2017] [Indexed: 11/13/2022]
Abstract
An anaerobic culture (1MN) was enriched with 1-methylnaphthalene as sole source of carbon and electrons and Fe(OH)3 as electron acceptor. 1-Naphthoic acid was produced as a metabolite during growth with 1-methylnaphthalene while 2-naphthoic acid was detected with naphthalene and 2-methylnaphthalene. This indicates that the degradation pathway of 1-methylnaphthalene might differ from naphthalene and 2-methylnaphthalene degradation in sulfate reducers. Terminal restriction fragment length polymorphism and pyrosequencing revealed that the culture is mainly composed of two bacteria related to uncultured Gram-positive Thermoanaerobacteraceae and uncultured gram-negative Desulfobulbaceae. Stable isotope probing showed that a 13C-carbon label from 13C10-naphthalene as growth substrate was mostly incorporated by the Thermoanaerobacteraceae. The presence of putative genes involved in naphthalene degradation in the genome of this organism was confirmed via assembly-based metagenomics and supports that it is the naphthalene-degrading bacterium in the culture. Thermoanaerobacteraceae have previously been detected in oil sludge under thermophilic conditions, but have not been shown to degrade hydrocarbons so far. The second member of the community belongs to the Desulfobulbaceae and has high sequence similarity to uncultured bacteria from contaminated sites including recently proposed groundwater cable bacteria. We suggest that the gram-positive Thermoanaerobacteraceae degrade polycyclic aromatic hydrocarbons while the Desulfobacterales are mainly responsible for Fe(III) reduction.
Collapse
|
76
|
Evidence of mixotrophic carbon-capture by n-butanol-producer Clostridium beijerinckii. Sci Rep 2017; 7:12759. [PMID: 28986542 PMCID: PMC5630571 DOI: 10.1038/s41598-017-12962-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 09/13/2017] [Indexed: 12/17/2022] Open
Abstract
Recent efforts to combat increasing greenhouse gas emissions include their capture into advanced biofuels, such as butanol. Traditionally, biobutanol research has been centered solely on its generation from sugars. Our results show partial re-assimilation of CO2 and H2 by n-butanol-producer C. beijerinckii. This was detected as synchronous CO2/H2 oscillations by direct (real-time) monitoring of their fermentation gasses. Additional functional analysis demonstrated increased total carbon recovery above heterotrophic values associated to mixotrophic assimilation of synthesis gas (H2, CO2 and CO). This was further confirmed using 13C-Tracer experiments feeding 13CO2 and measuring the resulting labeled products. Genome- and transcriptome-wide analysis revealed transcription of key C-1 capture and additional energy conservation genes, including partial Wood-Ljungdahl and complete reversed pyruvate ferredoxin oxidoreductase / pyruvate-formate-lyase-dependent (rPFOR/Pfl) pathways. Therefore, this report provides direct genetic and physiological evidences of mixotrophic inorganic carbon-capture by C. beijerinckii.
Collapse
|
77
|
Chen G, Murdoch RW, Mack EE, Seger ES, Löffler FE. Complete Genome Sequence of Dehalobacterium formicoaceticum Strain DMC, a Strictly Anaerobic Dichloromethane-Degrading Bacterium. GENOME ANNOUNCEMENTS 2017; 5:e00897-17. [PMID: 28912314 PMCID: PMC5597755 DOI: 10.1128/genomea.00897-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 07/26/2017] [Indexed: 01/17/2023]
Abstract
Dehalobacterium formicoaceticum utilizes dichloromethane as the sole energy source in defined anoxic bicarbonate-buffered mineral salt medium. The products are formate, acetate, inorganic chloride, and biomass. The bacterium's genome was sequenced using PacBio, assembled, and annotated. The complete genome consists of one 3.77-Mb circular chromosome harboring 3,935 predicted protein-encoding genes.
Collapse
Affiliation(s)
- Gao Chen
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee, USA
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Robert W Murdoch
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee, USA
| | - E Erin Mack
- Corporate Remediation Group, E. I. DuPont de Nemours and Company, Newark, Delaware, USA
| | | | - Frank E Löffler
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee, USA
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee, USA
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| |
Collapse
|
78
|
Qin QS, Feng DS, Liu PF, He Q, Li X, Liu AM, Zhang H, Hu GQ, Cheng L. Metagenomic Characterization of Candidatus Smithella cisternae Strain M82_1, a Syntrophic Alkane-Degrading Bacteria, Enriched from the Shengli Oil Field. Microbes Environ 2017; 32:234-243. [PMID: 28781346 PMCID: PMC5606693 DOI: 10.1264/jsme2.me17022] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The methanogenic degradation of hydrocarbons plays an important role in hydrocarbon-contaminated environments in the absence of an external electron acceptor. Members of Syntrophaceae sublineages were previously reported to be responsible for syntrophic alkane degradation. However, limited information is currently available on their physiological capabilities in nature because it is very challenging to cultivate these as-yet uncultured microbes. We herein performed metagenomic sequencing of the methanogenic hexadecane-degrading culture M82 and recovered a nearly complete genome (2.75 Mb, estimated completeness ≥97%) belonging to Syntrophaceae sublineage II. The assembly genome was tentatively named “Candidatus Smithella cisternae strain M82_1”. Genes encoding alkylsuccinate synthase for alkane activation were identified, suggesting that this organism is capable of oxidizing alkanes through fumarate addition. This capability was further supported by the detection of methyl pentadecyl succinic acid and methyl tetradecyl succinic acid in cultures amended with hexadecane and pentadecane, respectively. Genes encoding enzymes for the β-oxidation of long-chain fatty acids and butyrate were also identified. The electron transfer flavoprotein/DUF224 complex is presumed to link electron flow from acyl-CoA dehydrogenase to a membrane hydrogenase or formate dehydrogenase. Although no indications of Rnf complexes were detected, genes encoding electron-confurcating hydrogenase and formate dehydrogenase were proposed to couple the thermodynamically favorable oxidation of ferredoxin to generate H2 and formate from NADH. Strain M82_1 synthesized ATP from acetyl-CoA by substrate-level phosphorylation or F1F0-ATP synthases. These results provide an insight into the potential metabolic traits and ecophysiological roles of the syntrophic alkane degrader Syntrophaceae.
Collapse
Affiliation(s)
- Qian-Shan Qin
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | | | - Peng-Fei Liu
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | - Qiao He
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | - Xia Li
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | | | - Hui Zhang
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | - Guo-Quan Hu
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| | - Lei Cheng
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture
| |
Collapse
|
79
|
Genomic Analysis of Calderihabitans maritimus KKC1, a Thermophilic, Hydrogenogenic, Carboxydotrophic Bacterium Isolated from Marine Sediment. Appl Environ Microbiol 2017; 83:AEM.00832-17. [PMID: 28526793 DOI: 10.1128/aem.00832-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 05/13/2017] [Indexed: 11/20/2022] Open
Abstract
Calderihabitans maritimus KKC1 is a thermophilic, hydrogenogenic carboxydotroph isolated from a submerged marine caldera. Here, we describe the de novo sequencing and feature analysis of the C. maritimus KKC1 genome. Genome-based phylogenetic analysis confirmed that C. maritimus KKC1 was most closely related to the genus Moorella, which includes well-studied acetogenic members. Comparative genomic analysis revealed that, like Moorella, C. maritimus KKC1 retained both the CO2-reducing Wood-Ljungdahl pathway and energy-converting hydrogenase-based module activated by reduced ferredoxin, but it lacked the HydABC and NfnAB electron-bifurcating enzymes and pyruvate:ferredoxin oxidoreductase required for ferredoxin reduction for acetogenic growth. Furthermore, C. maritimus KKC1 harbored six genes encoding CooS, a catalytic subunit of the anaerobic CO dehydrogenase that can reduce ferredoxin via CO oxidation, whereas Moorella possessed only two CooS genes. Our analysis revealed that three cooS genes formed known gene clusters in other microorganisms, i.e., cooS-acetyl coenzyme A (acetyl-CoA) synthase (which contained a frameshift mutation), cooS-energy-converting hydrogenase, and cooF-cooS-FAD-NAD oxidoreductase, while the other three had novel genomic contexts. Sequence composition analysis indicated that these cooS genes likely evolved from a common ancestor. Collectively, these data suggest that C. maritimus KKC1 may be highly dependent on CO as a low-potential electron donor to directly reduce ferredoxin and may be more suited to carboxydotrophic growth compared to the acetogenic growth observed in Moorella, which show adaptation at a thermodynamic limit.IMPORTANCECalderihabitans maritimus KKC1 and members of the genus Moorella are phylogenetically related but physiologically distinct. The former is a hydrogenogenic carboxydotroph that can grow on carbon monoxide (CO) with H2 production, whereas the latter include acetogenic bacteria that grow on H2 plus CO2 with acetate production. Both species may require reduced ferredoxin as an actual "energy equivalent," but ferredoxin is a low-potential electron carrier and requires a high-energy substrate as an electron donor for reduction. Comparative genomic analysis revealed that C. maritimus KKC1 lacked specific electron-bifurcating enzymes and possessed six CO dehydrogenases, unlike Moorella species. This suggests that C. maritimus KKC1 may be more dependent on CO, a strong electron donor that can directly reduce ferredoxin via CO dehydrogenase, and may exhibit a survival strategy different from that of acetogenic Moorella, which solves the energetic barrier associated with endergonic reduction of ferredoxin with hydrogen.
Collapse
|
80
|
De Tissera S, Köpke M, Simpson SD, Humphreys C, Minton NP, Dürre P. Syngas Biorefinery and Syngas Utilization. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017. [DOI: 10.1007/10_2017_5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
81
|
Islam MA, Hadadi N, Ataman M, Hatzimanikatis V, Stephanopoulos G. Exploring biochemical pathways for mono-ethylene glycol (MEG) synthesis from synthesis gas. Metab Eng 2017; 41:173-181. [PMID: 28433737 DOI: 10.1016/j.ymben.2017.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/28/2016] [Accepted: 04/16/2017] [Indexed: 10/19/2022]
Abstract
Mono-ethylene glycol (MEG) is an important petrochemical with widespread use in numerous consumer products. The current industrial MEG-production process relies on non-renewable fossil fuel-based feedstocks, such as petroleum, natural gas, and naphtha; hence, it is useful to explore alternative routes of MEG-synthesis from gases as they might provide a greener and more sustainable alternative to the current production methods. Technologies of synthetic biology and metabolic engineering of microorganisms can be deployed for the expression of new biochemical pathways for MEG-synthesis from gases, provided that such promising alternative routes are first identified. We used the BNICE.ch algorithm to develop novel and previously unknown biological pathways to MEG from synthesis gas by leveraging the Wood-Ljungdahl pathway of carbon fixation of acetogenic bacteria. We developed a set of useful pathway pruning and analysis criteria to systematically assess thousands of pathways generated by BNICE.ch. Published genome-scale models of Moorella thermoacetica and Clostridium ljungdahlii were used to perform the pathway yield calculations and in-depth analyses of seven (7) newly developed biological MEG-producing pathways from gases, including CO2, CO, and H2. These analyses helped identify not only better candidate pathways, but also superior chassis organisms that can be used for metabolic engineering of the candidate pathways. The pathway generation, pruning, and detailed analysis procedures described in this study can also be used to develop biochemical pathways for other commodity chemicals from gaseous substrates.
Collapse
Affiliation(s)
- M Ahsanul Islam
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Noushin Hadadi
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Meric Ataman
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Vassily Hatzimanikatis
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
| |
Collapse
|
82
|
Heijstra BD, Leang C, Juminaga A. Gas fermentation: cellular engineering possibilities and scale up. Microb Cell Fact 2017; 16:60. [PMID: 28403896 PMCID: PMC5389167 DOI: 10.1186/s12934-017-0676-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 04/04/2017] [Indexed: 12/11/2022] Open
Abstract
Low carbon fuels and chemicals can be sourced from renewable materials such as biomass or from industrial and municipal waste streams. Gasification of these materials allows all of the carbon to become available for product generation, a clear advantage over partial biomass conversion into fermentable sugars. Gasification results into a synthesis stream (syngas) containing carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2) and nitrogen (N2). Autotrophy-the ability to fix carbon such as CO2 is present in all domains of life but photosynthesis alone is not keeping up with anthropogenic CO2 output. One strategy is to curtail the gaseous atmospheric release by developing waste and syngas conversion technologies. Historically microorganisms have contributed to major, albeit slow, atmospheric composition changes. The current status and future potential of anaerobic gas-fermenting bacteria with special focus on acetogens are the focus of this review.
Collapse
Affiliation(s)
| | - Ching Leang
- LanzaTech, Inc., 8045 Lamon Ave, Suite 400, Skokie, IL USA
| | - Alex Juminaga
- LanzaTech, Inc., 8045 Lamon Ave, Suite 400, Skokie, IL USA
| |
Collapse
|
83
|
Mayumi D, Mochimaru H, Tamaki H, Yamamoto K, Yoshioka H, Suzuki Y, Kamagata Y, Sakata S. Methane production from coal by a single methanogen. Science 2017; 354:222-225. [PMID: 27738170 DOI: 10.1126/science.aaf8821] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/29/2016] [Indexed: 02/05/2023]
Abstract
Coal-bed methane is one of the largest unconventional natural gas resources. Although microbial activity may greatly contribute to coal-bed methane formation, it is unclear whether the complex aromatic organic compounds present in coal can be used for methanogenesis. We show that deep subsurface-derived Methermicoccus methanogens can produce methane from more than 30 types of methoxylated aromatic compounds (MACs) as well as from coals containing MACs. In contrast to known methanogenesis pathways involving one- and two-carbon compounds, this "methoxydotrophic" mode of methanogenesis couples O-demethylation, CO2 reduction, and possibly acetyl-coenzyme A metabolism. Because MACs derived from lignin may occur widely in subsurface sediments, methoxydotrophic methanogenesis would play an important role in the formation of natural gas not limited to coal-bed methane and in the global carbon cycle.
Collapse
Affiliation(s)
- Daisuke Mayumi
- Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan
| | - Hanako Mochimaru
- Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan
| | - Hideyuki Tamaki
- Bioproduction Research Institute, AIST, 1-1-1 Higashi, Tsukuba 305-8566, Japan
| | - Kyosuke Yamamoto
- Bioproduction Research Institute, AIST, 1-1-1 Higashi, Tsukuba 305-8566, Japan
| | - Hideyoshi Yoshioka
- Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan
| | - Yuichiro Suzuki
- Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan
| | - Yoichi Kamagata
- Bioproduction Research Institute, AIST, 1-1-1 Higashi, Tsukuba 305-8566, Japan.
| | - Susumu Sakata
- Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
| |
Collapse
|
84
|
Homolactic Acid Fermentation by the Genetically Engineered Thermophilic Homoacetogen Moorella thermoacetica ATCC 39073. Appl Environ Microbiol 2017; 83:AEM.00247-17. [PMID: 28159797 DOI: 10.1128/aem.00247-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 11/20/2022] Open
Abstract
For the efficient production of target metabolites from carbohydrates, syngas, or H2-CO2 by genetically engineered Moorella thermoacetica, the control of acetate production (a main metabolite of M. thermoacetica) is desired. Although propanediol utilization protein (PduL) was predicted to be a phosphotransacetylase (PTA) involved in acetate production in M. thermoacetica, this has not been confirmed. Our findings described herein directly demonstrate that two putative PduL proteins, encoded by Moth_0864 (pduL1) and Moth_1181 (pduL2), are involved in acetate formation as PTAs. To disrupt these genes, we replaced each gene with a lactate dehydrogenase gene from Thermoanaerobacter pseudethanolicus ATCC 33223 (T-ldh). The acetate production from fructose as the sole carbon source by the pduL1 deletion mutant was not deficient, whereas the disruption of pduL2 significantly decreased the acetate yield to approximately one-third that of the wild-type strain. The double-deletion (both pduL genes) mutant did not produce acetate but produced only lactate as the end product from fructose. These results suggest that both pduL genes are associated with acetate formation via acetyl-coenzyme A (acetyl-CoA) and that their disruption enables a shift in the homoacetic pathway to the genetically synthesized homolactic pathway via pyruvate.IMPORTANCE This is the first report, to our knowledge, on the experimental identification of PTA genes in M. thermoacetica and the shift of the native homoacetic pathway to the genetically synthesized homolactic pathway by their disruption on a sugar platform.
Collapse
|
85
|
First Insights into the Genome Sequence of the Strictly Anaerobic Homoacetogenic Sporomusa sphaeroides Strain E (DSM 2875). GENOME ANNOUNCEMENTS 2017; 5:5/12/e00037-17. [PMID: 28336590 PMCID: PMC5364215 DOI: 10.1128/genomea.00037-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Here, we report the draft genome sequence of Sporomusa sphaeroides strain E (DSM 2875), a strict anaerobic homoacetogenic bacterium. It is able to grow autotrophically on different one-carbon compounds. The strain possesses several genes of the Wood-Ljungdahl pathway. The genome consists of a single chromosome (4.98 Mb).
Collapse
|
86
|
Ahlert S, Zimmermann R, Ebling J, König H. Analysis of propionate-degrading consortia from agricultural biogas plants. Microbiologyopen 2016; 5:1027-1037. [PMID: 27364538 PMCID: PMC5221444 DOI: 10.1002/mbo3.386] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 02/02/2023] Open
Abstract
In order to investigate the propionate-degrading community of agricultural biogas plants, four propionate-degrading consortia (Ap1a, N12, G12, and Wp2a) were established from different biogas plants which were fed with renewable resources. The consortia were cultivated in a batch for a period of 2-4 years and then analyzed in an 8-week batch experiment for microbial succession during propionate degradation. Community shifts showed considerable propagation of Syntrophobacter sulfatireducens, Cryptanaerobacter sp./Pelotomaculum sp., and "Candidatus Cloacamonas sp." in the course of decreasing propionate concentration. Methanogenic species belonged mainly to the genera Methanosarcina, Methanosaeta, and Methanoculleus. Due to the prevalent presence of the syntrophic acetate-oxidizing species Tepidanaerobacter acetatoxydans and potentially autotrophic homoacetogenic bacteria (Moorella sp., Thermacetogenium sp.), a theoretical involvement of syntrophic acetate oxidation and autotrophic homoacetogenesis in stable and efficient propionate degradation was indicated. Considering theoretical Gibbs free energy values at different hydrogen partial pressures, it is noticeable that syntrophic acetate oxidation and autotrophic homoacetogenesis have the potential to counterbalance adverse hydrogen partial pressure fluctuations, stabilizing most probably continuous and stable propionate degradation.
Collapse
Affiliation(s)
- Stephan Ahlert
- Institute of Microbiology and Wine ResearchJohannes Gutenberg UniversityMainzGermany
| | - Rita Zimmermann
- Institute of Microbiology and Wine ResearchJohannes Gutenberg UniversityMainzGermany
| | - Johannes Ebling
- Institute of Microbiology and Wine ResearchJohannes Gutenberg UniversityMainzGermany
| | - Helmut König
- Institute of Microbiology and Wine ResearchJohannes Gutenberg UniversityMainzGermany
| |
Collapse
|
87
|
Spectroscopic elucidation of energy transfer in hybrid inorganic-biological organisms for solar-to-chemical production. Proc Natl Acad Sci U S A 2016; 113:11750-11755. [PMID: 27698140 DOI: 10.1073/pnas.1610554113] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The rise of inorganic-biological hybrid organisms for solar-to-chemical production has spurred mechanistic investigations into the dynamics of the biotic-abiotic interface to drive the development of next-generation systems. The model system, Moorella thermoacetica-cadmium sulfide (CdS), combines an inorganic semiconductor nanoparticle light harvester with an acetogenic bacterium to drive the photosynthetic reduction of CO2 to acetic acid with high efficiency. In this work, we report insights into this unique electrotrophic behavior and propose a charge-transfer mechanism from CdS to M. thermoacetica Transient absorption (TA) spectroscopy revealed that photoexcited electron transfer rates increase with increasing hydrogenase (H2ase) enzyme activity. On the same time scale as the TA spectroscopy, time-resolved infrared (TRIR) spectroscopy showed spectral changes in the 1,700-1,900-cm-1 spectral region. The quantum efficiency of this system for photosynthetic acetic acid generation also increased with increasing H2ase activity and shorter carrier lifetimes when averaged over the first 24 h of photosynthesis. However, within the initial 3 h of photosynthesis, the rate followed an opposite trend: The bacteria with the lowest H2ase activity photosynthesized acetic acid the fastest. These results suggest a two-pathway mechanism: a high quantum efficiency charge-transfer pathway to H2ase generating H2 as a molecular intermediate that dominates at long time scales (24 h), and a direct energy-transducing enzymatic pathway responsible for acetic acid production at short time scales (3 h). This work represents a promising platform to utilize conventional spectroscopic methodology to extract insights from more complex biotic-abiotic hybrid systems.
Collapse
|
88
|
Shin J, Song Y, Jeong Y, Cho BK. Analysis of the Core Genome and Pan-Genome of Autotrophic Acetogenic Bacteria. Front Microbiol 2016; 7:1531. [PMID: 27733845 PMCID: PMC5039349 DOI: 10.3389/fmicb.2016.01531] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 09/12/2016] [Indexed: 01/07/2023] Open
Abstract
Acetogens are obligate anaerobic bacteria capable of reducing carbon dioxide (CO2) to multicarbon compounds coupled to the oxidation of inorganic substrates, such as hydrogen (H2) or carbon monoxide (CO), via the Wood-Ljungdahl pathway. Owing to the metabolic capability of CO2 fixation, much attention has been focused on understanding the unique pathways associated with acetogens, particularly their metabolic coupling of CO2 fixation to energy conservation. Most known acetogens are phylogenetically and metabolically diverse bacteria present in 23 different bacterial genera. With the increased volume of available genome information, acetogenic bacterial genomes can be analyzed by comparative genome analysis. Even with the genetic diversity that exists among acetogens, the Wood-Ljungdahl pathway, a central metabolic pathway, and cofactor biosynthetic pathways are highly conserved for autotrophic growth. Additionally, comparative genome analysis revealed that most genes in the acetogen-specific core genome were associated with the Wood-Ljungdahl pathway. The conserved enzymes and those predicted as missing can provide insight into biological differences between acetogens and allow for the discovery of promising candidates for industrial applications.
Collapse
Affiliation(s)
- Jongoh Shin
- Systems and Synthetic Biology Laboratory, Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology Daejeon, South Korea
| | - Yoseb Song
- Systems and Synthetic Biology Laboratory, Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology Daejeon, South Korea
| | - Yujin Jeong
- Systems and Synthetic Biology Laboratory, Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology Daejeon, South Korea
| | - Byung-Kwan Cho
- Systems and Synthetic Biology Laboratory, Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea; Intelligent Synthetic Biology CenterDaejeon, South Korea
| |
Collapse
|
89
|
Abstract
Thermophilic microorganisms as well as acetogenic bacteria are both considered ancient. Interestingly, only a few species of bacteria, all belonging to the family Thermoanaerobacteraceae, are described to conserve energy from acetate formation with hydrogen as electron donor and carbon dioxide as electron acceptor. This review reflects the metabolic differences between Moorella spp., Thermoanaerobacter kivui and Thermacetogenium phaeum, with focus on the biochemistry of autotrophic growth and energy conservation. The potential of these thermophilic acetogens for biotechnological applications is discussed briefly.
Collapse
Affiliation(s)
- Mirko Basen
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt Am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt Am Main, Germany.
| |
Collapse
|
90
|
Melton ED, Sorokin DY, Overmars L, Chertkov O, Clum A, Pillay M, Ivanova N, Shapiro N, Kyrpides NC, Woyke T, Lapidus AL, Muyzer G. Complete genome sequence of Desulfurivibrio alkaliphilus strain AHT2(T), a haloalkaliphilic sulfidogen from Egyptian hypersaline alkaline lakes. Stand Genomic Sci 2016; 11:67. [PMID: 27617057 PMCID: PMC5016858 DOI: 10.1186/s40793-016-0184-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/25/2016] [Indexed: 11/18/2022] Open
Abstract
Desulfurivibrio alkaliphilus strain AHT2T is a strictly anaerobic sulfidogenic haloalkaliphile isolated from a composite sediment sample of eight hypersaline alkaline lakes in the Wadi al Natrun valley in the Egyptian Libyan Desert. D. alkaliphilus AHT2T is Gram-negative and belongs to the family Desulfobulbaceae within the Deltaproteobacteria. Here we report its genome sequence, which contains a 3.10 Mbp chromosome. D. alkaliphilus AHT2T is adapted to survive under highly alkaline and moderately saline conditions and therefore, is relevant to the biotechnology industry and life under extreme conditions. For these reasons, D. alkaliphilus AHT2T was sequenced by the DOE Joint Genome Institute as part of the Community Science Program.
Collapse
Affiliation(s)
- Emily Denise Melton
- Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Dimitry Y Sorokin
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology, RAS, Moscow, Russia ; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Lex Overmars
- Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Olga Chertkov
- Bioscience Division, Department of Energy Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
| | - Alicia Clum
- Joint Genome Institute, Walnut Creek, CA USA
| | - Manoj Pillay
- Biological Data Management and Technology Center, Lawrence Berkeley National Laboratory, Berkeley, CA USA
| | | | | | - Nikos C Kyrpides
- Joint Genome Institute, Walnut Creek, CA USA ; Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Tanja Woyke
- Joint Genome Institute, Walnut Creek, CA USA
| | - Alla L Lapidus
- Center for Algorithmic Biotechnology, Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Gerard Muyzer
- Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
91
|
Wang Y, Gao ZM, Li JT, Bougouffa S, Tian RM, Bajic VB, Qian PY. Draft genome of an Aerophobetes bacterium reveals a facultative lifestyle in deep-sea anaerobic sediments. Sci Bull (Beijing) 2016. [DOI: 10.1007/s11434-016-1135-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
92
|
Heyer R, Benndorf D, Kohrs F, De Vrieze J, Boon N, Hoffmann M, Rapp E, Schlüter A, Sczyrba A, Reichl U. Proteotyping of biogas plant microbiomes separates biogas plants according to process temperature and reactor type. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:155. [PMID: 27462366 PMCID: PMC4960849 DOI: 10.1186/s13068-016-0572-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 07/12/2016] [Indexed: 05/23/2023]
Abstract
BACKGROUND Methane yield and biogas productivity of biogas plants (BGPs) depend on microbial community structure and function, substrate supply, and general biogas process parameters. So far, however, relatively little is known about correlations between microbial community function and process parameters. To close this knowledge gap, microbial communities of 40 samples from 35 different industrial biogas plants were evaluated by a metaproteomics approach in this study. RESULTS Liquid chromatography coupled to tandem mass spectrometry (Orbitrap Elite™ Hybrid Ion Trap-Orbitrap Mass Spectrometer) of all 40 samples as triplicate enabled the identification of 3138 different metaproteins belonging to 162 biological processes and 75 different taxonomic orders. The respective database searches were performed against UniProtKB/Swiss-Prot and seven metagenome databases. Subsequent clustering and principal component analysis of these data allowed for the identification of four main clusters associated with mesophile and thermophile process conditions, the use of upflow anaerobic sludge blanket reactors and BGP feeding with sewage sludge. Observations confirm a previous phylogenetic study of the same BGP samples that was based on 16S rRNA gene sequencing by De Vrieze et al. (Water Res 75:312-323, 2015). In particular, we identified similar microbial key players of biogas processes, namely Bacillales, Enterobacteriales, Bacteriodales, Clostridiales, Rhizobiales and Thermoanaerobacteriales as well as Methanobacteriales, Methanosarcinales and Methanococcales. For the elucidation of the main biomass degradation pathways, the most abundant 1 % of metaproteins was assigned to the KEGG map 1200 representing the central carbon metabolism. Additionally, the effect of the process parameters (i) temperature, (ii) organic loading rate (OLR), (iii) total ammonia nitrogen (TAN), and (iv) sludge retention time (SRT) on these pathways was investigated. For example, high TAN correlated with hydrogenotrophic methanogens and bacterial one-carbon metabolism, indicating syntrophic acetate oxidation. CONCLUSIONS This is the first large-scale metaproteome study of BGPs. Proteotyping of BGPs reveals general correlations between the microbial community structure and its function with process parameters. The monitoring of changes on the level of microbial key functions or even of the microbial community represents a well-directed tool for the identification of process problems and disturbances.Graphical abstractCorrelation between the different orders and process parameter, as well as principle component analysis of all investigated biogas plants based on the identified metaproteins.
Collapse
Affiliation(s)
- R. Heyer
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
- Bioprocess Engineering, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - D. Benndorf
- Bioprocess Engineering, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - F. Kohrs
- Bioprocess Engineering, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - J. De Vrieze
- Laboratory of Microbial Technology and Ecology (LabMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - N. Boon
- Laboratory of Microbial Technology and Ecology (LabMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - M. Hoffmann
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
| | - E. Rapp
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
| | - Andreas Schlüter
- Center for Biotechnology, Genome Research of Industrial Microorganisms, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Alexander Sczyrba
- Center for Biotechnology, Computational Metagenomics, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - U. Reichl
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
- Bioprocess Engineering, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
| |
Collapse
|
93
|
Abstract
Acetogenic bacteria are a diverse group of strictly anaerobic bacteria that utilize the Wood-Ljungdahl pathway for CO2 fixation and energy conservation. These microorganisms play an important part in the global carbon cycle and are a key component of the anaerobic food web. Their most prominent metabolic feature is autotrophic growth with molecular hydrogen and carbon dioxide as the substrates. However, most members also show an outstanding metabolic flexibility for utilizing a vast variety of different substrates. In contrast to autotrophic growth, which is hardly competitive, metabolic flexibility is seen as a key ability of acetogens to compete in ecosystems and might explain the almost-ubiquitous distribution of acetogenic bacteria in anoxic environments. This review covers the latest findings with respect to the heterotrophic metabolism of acetogenic bacteria, including utilization of carbohydrates, lactate, and different alcohols, especially in the model acetogen Acetobacterium woodii Modularity of metabolism, a key concept of pathway design in synthetic biology, together with electron bifurcation, to overcome energetic barriers, appears to be the basis for the amazing substrate spectrum. At the same time, acetogens depend on only a relatively small number of enzymes to expand the substrate spectrum. We will discuss the energetic advantages of coupling CO2 reduction to fermentations that exploit otherwise-inaccessible substrates and the ecological advantages, as well as the biotechnological applications of the heterotrophic metabolism of acetogens.
Collapse
|
94
|
Breitkopf R, Uhlig R, Drenckhan T, Fischer RJ. Two propanediol utilization-like proteins of Moorella thermoacetica with phosphotransacetylase activity. Extremophiles 2016; 20:653-61. [PMID: 27338272 DOI: 10.1007/s00792-016-0854-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/14/2016] [Indexed: 12/16/2022]
Abstract
Moorella thermoacetica is one of the model acetogenic bacteria for the resolution of the Wood-Ljungdahl (acetyl-CoA) pathway in which CO2 is autotrophically assimilated yielding acetyl-CoA as central intermediate. Its further conversion into acetate relies on subsequent phosphotransacetylase (PTA) and acetate kinase reactions. However, the genome of M. thermoacetica contains no pta homologous gene. It has been speculated that the moth_0864 and moth_1181 gene products sharing similarities with an evolutionarily distinct phosphotransacylase involved in 1,2-propanediol utilization (PDUL) of Salmonella enterica act as PTAs in M. thermoacetica. Here, we demonstrate specific PTA activities with acetyl-CoA as substrate of 9.05 and 2.03 U/mg for the recombinant enzymes PDUL1 (Moth_1181) and PDUL2 (Moth_0864), respectively. Both showed maximal activity at 65 °C and pH 7.6. Native proteins (90 kDa) are homotetramers composed of four subunits with apparent molecular masses of about 23 kDa. Thus, one or both PDULs of M. thermoacetica might act as PTAs in vivo catalyzing the penultimate step of the Wood-Ljungdahl pathway toward the formation of acetate. In silico analysis underlined that up to now beside of M. thermoacetica, only Sporomusa ovata contains only PDUL like class(III)-PTAs but no other phosphotransacetylases or phosphotransbutyrylases (PTBs).
Collapse
Affiliation(s)
- Ronja Breitkopf
- BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Ronny Uhlig
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany
| | - Tina Drenckhan
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany
| | - Ralf-Jörg Fischer
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany.
| |
Collapse
|
95
|
Fermentation of lignocellulosic sugars to acetic acid by Moorella thermoacetica. ACTA ACUST UNITED AC 2016; 43:807-16. [DOI: 10.1007/s10295-016-1756-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
Abstract
Abstract
A systematic study of bioconversion of lignocellulosic sugars to acetic acid by Moorella thermoacetica (strain ATCC 39073) was conducted. Four different water-soluble fractions (hydrolysates) obtained after steam pretreatment of lignocellulosic biomass were selected and fermented to acetic acid in batch fermentations. M. thermoacetica can effectively ferment xylose and glucose in hydrolysates from wheat straw, forest residues, switchgrass, and sugarcane straw to acetic acid. Xylose and glucose were completely utilized, with xylose being consumed first. M. thermoacetica consumed up to 62 % of arabinose, 49 % galactose and 66 % of mannose within 72 h of fermentation in the mixture of lignocellulosic sugars. The highest acetic acid yield was obtained from sugarcane straw hydrolysate, with 71 % of theoretical yield based on total sugars (17 g/L acetic acid from 24 g/L total sugars). The lowest acetic acid yield was observed in forest residues hydrolysate, with 39 % of theoretical yield based on total sugars (18 g/L acetic acid from 49 g/L total sugars). Process derived compounds from steam explosion pretreatment, including 5-hydroxymethylfurfural (0.4 g/L), furfural (0.1 g/L) and total phenolics (3 g/L), did not inhibit microbial growth and acetic acid production yield. This research identified two major factors that adversely affected acetic acid yield in all hydrolysates, especially in forest residues: (i) glucose to xylose ratio and (ii) incomplete consumption of arabinose, galactose and mannose. For efficient bioconversion of lignocellulosic sugars to acetic acid, it is imperative to have an appropriate balance of sugars in a hydrolysate. Hence, the choice of lignocellulosic biomass and steam pretreatment design are fundamental steps for the industrial application of this process.
Collapse
|
96
|
Genome Sequence of the Acetogenic Bacterium Moorella mulderi DSM 14980T. GENOME ANNOUNCEMENTS 2016; 4:4/3/e00444-16. [PMID: 27231372 PMCID: PMC4882953 DOI: 10.1128/genomea.00444-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Here, we report the draft genome sequence of Moorella mulderi DSM 14980T, a thermophilic acetogenic bacterium, which is able to grow autotrophically on H2 plus CO2 using the Wood-Ljungdahl pathway. The genome consists of a circular chromosome (2.99 Mb).
Collapse
|
97
|
Liew F, Martin ME, Tappel RC, Heijstra BD, Mihalcea C, Köpke M. Gas Fermentation-A Flexible Platform for Commercial Scale Production of Low-Carbon-Fuels and Chemicals from Waste and Renewable Feedstocks. Front Microbiol 2016; 7:694. [PMID: 27242719 PMCID: PMC4862988 DOI: 10.3389/fmicb.2016.00694] [Citation(s) in RCA: 206] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/26/2016] [Indexed: 12/13/2022] Open
Abstract
There is an immediate need to drastically reduce the emissions associated with global fossil fuel consumption in order to limit climate change. However, carbon-based materials, chemicals, and transportation fuels are predominantly made from fossil sources and currently there is no alternative source available to adequately displace them. Gas-fermenting microorganisms that fix carbon dioxide (CO2) and carbon monoxide (CO) can break this dependence as they are capable of converting gaseous carbon to fuels and chemicals. As such, the technology can utilize a wide range of feedstocks including gasified organic matter of any sort (e.g., municipal solid waste, industrial waste, biomass, and agricultural waste residues) or industrial off-gases (e.g., from steel mills or processing plants). Gas fermentation has matured to the point that large-scale production of ethanol from gas has been demonstrated by two companies. This review gives an overview of the gas fermentation process, focusing specifically on anaerobic acetogens. Applications of synthetic biology and coupling gas fermentation to additional processes are discussed in detail. Both of these strategies, demonstrated at bench-scale, have abundant potential to rapidly expand the commercial product spectrum of gas fermentation and further improve efficiencies and yields.
Collapse
|
98
|
Islam MA, Zengler K, Edwards EA, Mahadevan R, Stephanopoulos G. Investigating Moorella thermoacetica metabolism with a genome-scale constraint-based metabolic model. Integr Biol (Camb) 2016; 7:869-82. [PMID: 25994252 DOI: 10.1039/c5ib00095e] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Moorella thermoacetica is a strictly anaerobic, endospore-forming, and metabolically versatile acetogenic bacterium capable of conserving energy by both autotrophic (acetogenesis) and heterotrophic (homoacetogenesis) modes of metabolism. Its metabolic diversity and the ability to efficiently convert a wide range of compounds, including syngas (CO + H2) into acetyl-CoA have made this thermophilic bacterium a promising host for industrial biotechnology applications. However, lack of detailed information on M. thermoacetica's metabolism is a major impediment to its use as a microbial cell factory. In order to overcome this issue, a genome-scale constraint-based metabolic model of Moorella thermoacetica, iAI558, has been developed using its genome sequence and physiological data from published literature. The reconstructed metabolic network of M. thermoacetica comprises 558 metabolic genes, 705 biochemical reactions, and 698 metabolites. Of the total 705 model reactions, 680 are gene-associated while the rest are non-gene associated reactions. The model, in addition to simulating both autotrophic and heterotrophic growth of M. thermoacetica, revealed degeneracy in its TCA-cycle, a common characteristic of anaerobic metabolism. Furthermore, the model helped elucidate the poorly understood energy conservation mechanism of M. thermoacetica during autotrophy. Thus, in addition to generating experimentally testable hypotheses regarding its physiology, such a detailed model will facilitate rapid strain designing and metabolic engineering of M. thermoacetica for industrial applications.
Collapse
Affiliation(s)
- M Ahsanul Islam
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | | | | | | | | |
Collapse
|
99
|
Groher A, Weuster-Botz D. Comparative reaction engineering analysis of different acetogenic bacteria for gas fermentation. J Biotechnol 2016; 228:82-94. [PMID: 27107467 DOI: 10.1016/j.jbiotec.2016.04.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/08/2016] [Accepted: 04/19/2016] [Indexed: 01/05/2023]
Abstract
The production of chemicals by syngas fermentation is a promising alternative to heterotrophic fermentation processes. The autotrophic process performances of the so far not well studied acetogens Acetobacterium fimetarium, Acetobacterium wieringae, Blautia hydrogenotrophica, Clostridium magnum, Eubacterium aggregans, Sporomusa acidovorans, Sporomusa ovata and Terrisporobacter mayombei were characterized. Acetobacterium woodii was used as reference strain. Standardized batch experiments with continuous supply of the gaseous substrates CO2 and H2 were performed in fully controlled stirred-tank bioreactors. A. wieringae and S. ovata showed by far the highest growth rates and maximum biomass concentrations among the acetogens under study. Aside from the reference strain A. woodii, highest volumetric (17.96gL(-1)d(-1)) as well as cell specific acetate formation rates (21.03gg(-1)d(-1)) were observed with S. ovata resulting in a final acetate concentration of 32.2gL(-1). Accumulation of formate with up to 4.8gL(-1) was observed with all acetogens. Ethanol was produced autotrophically with up to 0.42gL(-1) by four of the acetogenic bacteria under study (A. wieringae, C. magnum, S. acidovorans and S. ovata) and also by A. woodii. Butyrate was formed with up to 0.14gL(-1) by three of the acetogenic bacteria under study (C. magnum, B. hydrogenotrophica and E. aggregans). Due to its superior process performances S. ovata may be a promising host for redirecting carbon fluxes by applying metabolic engineering and tools of synthetic biology to produce non-natural chemicals from syngas.
Collapse
Affiliation(s)
- Anna Groher
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, D 85748 Garching, Germany
| | - Dirk Weuster-Botz
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, D 85748 Garching, Germany.
| |
Collapse
|
100
|
CO Metabolism in the Thermophilic Acetogen Thermoanaerobacter kivui. Appl Environ Microbiol 2016; 82:2312-2319. [PMID: 26850300 DOI: 10.1128/aem.00122-16] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 01/31/2016] [Indexed: 12/14/2022] Open
Abstract
The thermophilic acetogenic bacterium Thermoanaerobacter kivui, previously described not to use carbon monoxide as a carbon and energy source, was adapted to grow on CO. This was achieved by using a preculture grown on H2 plus CO2 and by increasing the CO concentration in small, 10% increments.T. kivui was finally able to grow within a 100% CO atmosphere. Growth on CO was found in complex and mineral media, and vitamins were not required. Carbon monoxide consumption was accompanied by acetate and hydrogen production. Cells also grew on synthesis gas (syngas) with the simultaneous use of CO and H2 coupled to acetate production. CO oxidation in resting cells was coupled to hydrogen and acetate production and accompanied by the synthesis of ATP. A protonophore abolished ATP synthesis but stimulated H2 production, which is consistent with a chemiosmotic mechanism of ATP synthesis. Hydrogenase activity was highest in crude extracts of CO-grown cells, and carbon monoxide dehydrogenase (CODH) activity was highest in H2-plus-CO2- or CO-grown cells. The genome of T. kivui harbors two CODH gene clusters, and both CODH proteins were present in crude extracts, but one CODH was more prevalent in crude extracts from CO-grown cells.
Collapse
|