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Vailionis JL, Zhao W, Zhang K, Rodionov DA, Lipscomb GL, Tanwee TNN, O'Quinn HC, Bing RG, Kelly RM, Adams MWW, Zhang Y. Optimizing Strategies for Bio-Based Ethanol Production Using Genome-Scale Metabolic Modeling of the Hyperthermophilic Archaeon, Pyrococcus furiosus. Appl Environ Microbiol 2023; 89:e0056323. [PMID: 37289085 PMCID: PMC10304669 DOI: 10.1128/aem.00563-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/13/2023] [Indexed: 06/09/2023] Open
Abstract
A genome-scale metabolic model, encompassing a total of 623 genes, 727 reactions, and 865 metabolites, was developed for Pyrococcus furiosus, an archaeon that grows optimally at 100°C by carbohydrate and peptide fermentation. The model uses subsystem-based genome annotation, along with extensive manual curation of 237 gene-reaction associations including those involved in central carbon metabolism, amino acid metabolism, and energy metabolism. The redox and energy balance of P. furiosus was investigated through random sampling of flux distributions in the model during growth on disaccharides. The core energy balance of the model was shown to depend on high acetate production and the coupling of a sodium-dependent ATP synthase and membrane-bound hydrogenase, which generates a sodium gradient in a ferredoxin-dependent manner, aligning with existing understanding of P. furiosus metabolism. The model was utilized to inform genetic engineering designs that favor the production of ethanol over acetate by implementing an NADPH and CO-dependent energy economy. The P. furiosus model is a powerful tool for understanding the relationship between generation of end products and redox/energy balance at a systems-level that will aid in the design of optimal engineering strategies for production of bio-based chemicals and fuels. IMPORTANCE The bio-based production of organic chemicals provides a sustainable alternative to fossil-based production in the face of today's climate challenges. In this work, we present a genome-scale metabolic reconstruction of Pyrococcus furiosus, a well-established platform organism that has been engineered to produce a variety of chemicals and fuels. The metabolic model was used to design optimal engineering strategies to produce ethanol. The redox and energy balance of P. furiosus was examined in detail, which provided useful insights that will guide future engineering designs.
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Affiliation(s)
- Jason L. Vailionis
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Weishu Zhao
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Ke Zhang
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Dmitry A. Rodionov
- Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Gina L. Lipscomb
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Tania N. N. Tanwee
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Hailey C. O'Quinn
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Ryan G. Bing
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Ying Zhang
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
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2
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Garg D, Samota MK, Kontis N, Patel N, Bala S, Rosado AS. Revolutionizing biofuel generation: Unleashing the power of CRISPR-Cas mediated gene editing of extremophiles. Microbiol Res 2023; 274:127443. [PMID: 37399654 DOI: 10.1016/j.micres.2023.127443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/20/2023] [Accepted: 06/23/2023] [Indexed: 07/05/2023]
Abstract
Molecular biology techniques like gene editing have altered the specific genes in micro-organisms to increase their efficiency to produce biofuels. This review paper investigates the outcomes of Clustered regularly interspaced short palindromic repeats (CRISPR) for gene editing in extremophilic micro-organisms to produce biofuel. Commercial production of biofuel from lignocellulosic waste is limited due to various constraints. A potential strategy to enhance the capability of extremophiles to produce biofuel is gene-editing via CRISPR-Cas technology. The efficiency of intracellular enzymes like cellulase, hemicellulose in extremophilic bacteria, fungi and microalgae has been increased by alteration of genes associated with enzymatic activity and thermotolerance. extremophilic microbes like Thermococcus kodakarensis, Thermotoga maritima, Thermus thermophilus, Pyrococcus furiosus and Sulfolobus sp. are explored for biofuel production. The conversion of lignocellulosic biomass into biofuels involves pretreatment, hydrolysis and fermentation. The challenges like off-target effect associated with use of extremophiles for biofuel production is also addressed. The appropriate regulations are required to maximize effectiveness while minimizing off-target cleavage, as well as the total biosafety of this technique. The latest discovery of the CRISPR-Cas system should provide a new channel in the creation of microbial biorefineries through site- specific gene editing that might boost the generation of biofuels from extremophiles. Overall, this review study highlights the potential for genome editing methods to improve the potential of extremophiles to produce biofuel, opening the door to more effective and environmentally friendly biofuel production methods.
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Affiliation(s)
- Diksha Garg
- Department of Microbiology, Punjab Agricultural University, Ludhiana, India
| | | | - Nicholas Kontis
- Red Sea Research Center, Biological and Environmental Science and Engineering Division,King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia; Computational Bioscience Research Center, Biological and Environmental Science and, Engineering Division, King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia
| | - Niketan Patel
- Red Sea Research Center, Biological and Environmental Science and Engineering Division,King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia; Computational Bioscience Research Center, Biological and Environmental Science and, Engineering Division, King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia
| | - Saroj Bala
- Department of Microbiology, Punjab Agricultural University, Ludhiana, India
| | - Alexandre Soares Rosado
- Red Sea Research Center, Biological and Environmental Science and Engineering Division,King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia; Computational Bioscience Research Center, Biological and Environmental Science and, Engineering Division, King Abdullah University of Science and Technology, Thuwal, Makkah 23955, Saudi Arabia.
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3
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Liang B, Sun G, Zhang X, Nie Q, Zhao Y, Yang J. Recent Advances, Challenges and Metabolic Engineering Strategies in the Biosynthesis of 3-Hydroxypropionic Acid. Biotechnol Bioeng 2022; 119:2639-2668. [PMID: 35781640 DOI: 10.1002/bit.28170] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/26/2022] [Accepted: 06/29/2022] [Indexed: 11/07/2022]
Abstract
As an attractive and valuable platform chemical, 3-hydroxypropionic acid (3-HP) can be used to produce a variety of industrially important commodity chemicals and biodegradable polymers. Moreover, the biosynthesis of 3-HP has drawn much attention in recent years due to its sustainability and environmental friendliness. Here, we focus on recent advances, challenges and metabolic engineering strategies in the biosynthesis of 3-HP. While glucose and glycerol are major carbon sources for its production of 3-HP via microbial fermentation, other carbon sources have also been explored. To increase yield and titer, synthetic biology and metabolic engineering strategies have been explored, including modifying pathway enzymes, eliminating flux blockages due to byproduct synthesis, eliminating toxic byproducts, and optimizing via genome-scale models. This review also provides insights on future directions for 3-HP biosynthesis. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Bo Liang
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Qingdao Agricultural University, Qingdao, China.,Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Guannan Sun
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Qingdao Agricultural University, Qingdao, China.,Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Xinping Zhang
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Qingdao Agricultural University, Qingdao, China.,Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Qingjuan Nie
- Foreign Languages School, Qingdao Agricultural University, Qingdao, China
| | - Yukun Zhao
- Pony Testing International Group, Qingdao, China
| | - Jianming Yang
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Qingdao Agricultural University, Qingdao, China.,Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, China
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4
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Pfeifer K, Ergal İ, Koller M, Basen M, Schuster B, Rittmann SKMR. Archaea Biotechnology. Biotechnol Adv 2020; 47:107668. [PMID: 33271237 DOI: 10.1016/j.biotechadv.2020.107668] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/13/2022]
Abstract
Archaea are a domain of prokaryotic organisms with intriguing physiological characteristics and ecological importance. In Microbial Biotechnology, archaea are historically overshadowed by bacteria and eukaryotes in terms of public awareness, industrial application, and scientific studies, although their biochemical and physiological properties show a vast potential for a wide range of biotechnological applications. Today, the majority of microbial cell factories utilized for the production of value-added and high value compounds on an industrial scale are bacterial, fungal or algae based. Nevertheless, archaea are becoming ever more relevant for biotechnology as their cultivation and genetic systems improve. Some of the main advantages of archaeal cell factories are the ability to cultivate many of these often extremophilic organisms under non-sterile conditions, and to utilize inexpensive feedstocks often toxic to other microorganisms, thus drastically reducing cultivation costs. Currently, the only commercially available products of archaeal cell factories are bacterioruberin, squalene, bacteriorhodopsin and diether-/tetraether-lipids, all of which are produced utilizing halophiles. Other archaeal products, such as carotenoids and biohydrogen, as well as polyhydroxyalkanoates and methane are in early to advanced development stages, respectively. The aim of this review is to provide an overview of the current state of Archaea Biotechnology by describing the actual state of research and development as well as the industrial utilization of archaeal cell factories, their role and their potential in the future of sustainable bioprocessing, and to illustrate their physiological and biotechnological potential.
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Affiliation(s)
- Kevin Pfeifer
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria; Institute of Synthetic Bioarchitectures, Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Wien, Austria
| | - İpek Ergal
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria
| | - Martin Koller
- Office of Research Management and Service, c/o Institute of Chemistry, University of Graz, Austria
| | - Mirko Basen
- Microbial Physiology Group, Division of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Bernhard Schuster
- Institute of Synthetic Bioarchitectures, Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Wien, Austria
| | - Simon K-M R Rittmann
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria.
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5
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Integration of large heterologous DNA fragments into the genome of Thermococcus kodakarensis. Extremophiles 2020; 24:339-353. [PMID: 32112303 DOI: 10.1007/s00792-020-01159-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/31/2020] [Indexed: 10/24/2022]
Abstract
In this study, a transformation system enabling large-scale gene recombination was developed for the hyperthermophilic archaeon Thermococcus kodakarensis. Using the uracil auxotroph T. kodakarensis KU216 (∆pyrF) as a parent strain, we constructed multiple host strains harboring two 1-kbp DNA regions from the genomes of either the hyperthermophilic archaeon Pyrococcus furiosus or Methanocaldococcus jannaschii. The two regions were selected so that the regions between them on the respective genomes would include pyrF genes, which can potentially be used for selection. Transformation using these host strains and genomic DNA from P. furiosus or M. jannaschii were carried out. Transformants with exogenous pyrF were obtained only using host strains with regions from P. furiosus, and only when the distances between the two regions were relatively short (2-5 kbp) on the P. furiosus genome. To insert longer DNA fragments, we examined the possibilities of using P. furiosus cells to provide intact genomic DNA. A cell pellet of P. furiosus was overlaid with that of T. kodakarensis so that cells were in direct contact. As a result, we were able to isolate T. kodakarensis strains harboring DNA fragments from P. furiosus with lengths of up to 75 kbp in a single transformation step.
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6
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Williams-Rhaesa AM, Adams MWW. Measuring Metabolic Enzyme Performance. Methods Mol Biol 2020; 2096:141-147. [PMID: 32720152 DOI: 10.1007/978-1-0716-0195-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding the performance of key metabolic enzymes is critical to metabolic engineering. It is important to know the kinetic parameters of both native enzymes and heterologously expressed enzymes that play key roles in pathway performance (Zeldes et al., Front Microbiol 6:1209, 2015; Keller et al., Metab Eng 27:101-106, 2015). This step cannot be overlooked as gene expression is not always a good indicator of the production of fully active enzymes, especially those requiring cofactor assembly and processing (Zeldes et al., Front Microbiol 6:1209, 2015; Chandrayan et al., J Biol Chem 287:3257-3264, 2012; Basen et al., MBio 3:e00053-e00012, 2012). Additionally, knowing kinetic parameters and having accurate and reproducible assays allows for the use of powerful computational and in vitro pathway optimization tools that can inform metabolic engineering efforts that in turn can lead to improvements in pathway performance (Keller et al., Metab Eng 27:101-106, 2015; Copeland et al., Metab Eng 14:270-280, 2012). To take full advantage of these tools, understanding the roles of both enzymes directly involved in a pathway of interest, together with those in related pathways that may syphon off key intermediates, is ideal (Keller et al., Metab Eng 27:101-106, 2015; Thorgersen et al., Metab Eng 22:83-88; Lin et al., Metab Engi 31:44-52, 2015).
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Affiliation(s)
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA.
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7
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A simple biosynthetic pathway for 2,3-butanediol production in Thermococcus onnurineus NA1. Appl Microbiol Biotechnol 2019; 103:3477-3485. [DOI: 10.1007/s00253-019-09724-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/05/2019] [Accepted: 02/24/2019] [Indexed: 11/25/2022]
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8
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Wu CH, Ponir CA, Haja DK, Adams MWW. Improved production of the NiFe-hydrogenase from Pyrococcus furiosus by increased expression of maturation genes. Protein Eng Des Sel 2018; 31:337-344. [DOI: 10.1093/protein/gzy025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 10/13/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chang-Hao Wu
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| | - Cynthia A Ponir
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| | - Dominik K Haja
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
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9
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Fuke T, Sato T, Jha S, Tansengco ML, Atomi H. Phytoene production utilizing the isoprenoid biosynthesis capacity of Thermococcus kodakarensis. Extremophiles 2018; 22:301-313. [PMID: 29340843 DOI: 10.1007/s00792-018-0998-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 12/23/2017] [Indexed: 10/18/2022]
Abstract
Phytoene (C40H64) is an isoprenoid and a precursor of various carotenoids which are of industrial value. Archaea can be considered to exhibit a relatively large capacity to produce isoprenoids, as they are components of their membrane lipids. Here, we aimed to produce isoprenoids such as phytoene in the hyperthermophilic archaeon Thermococcus kodakarensis. T. kodakarensis harbors a prenyltransferase gene involved in the biosynthesis of farnesyl pyrophosphate and geranylgeranyl pyrophosphate, which are precursors of squalene and phytoene, respectively. However, homologs of squalene synthase and phytoene synthase, which catalyze their condensation reactions, are not found on the genome. Therefore, a squalene/phytoene synthase homolog from an acidothermophilic archaeon Sulfolobus acidocaldarius, Saci_1734, was introduced into the T. kodakarensis chromosome under the control of a strong promoter. Production of the Saci_1734 protein was confirmed in this strain, and the generation of phytoene was detected (0.08-0.75 mg L-1 medium). We then carried out genetic engineering in order to increase the phytoene production yield. Disruption of an acetyl-CoA synthetase I gene involved in hydrolyzing acetyl-CoA, the precursor of phytoene, together with the introduction of a second copy of Saci_1734 led to a 3.4-fold enhancement in phytoene production.
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Affiliation(s)
- Tsubasa Fuke
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Takaaki Sato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.,JST, CREST, 7 Gobancho Chiyoda-ku, Tokyo, 102-0076, Japan
| | - Savyasachee Jha
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Myra L Tansengco
- Environment and Biotechnology Division, Industrial Technology Development Institute, Department of Science and Technology, Bicutan, Taguig, Metro Manila, Philippines
| | - Haruyuki Atomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan. .,JST, CREST, 7 Gobancho Chiyoda-ku, Tokyo, 102-0076, Japan.
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10
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Liu C, Ding Y, Xian M, Liu M, Liu H, Ma Q, Zhao G. Malonyl-CoA pathway: a promising route for 3-hydroxypropionate biosynthesis. Crit Rev Biotechnol 2017; 37:933-941. [PMID: 28078904 DOI: 10.1080/07388551.2016.1272093] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
3-Hydroxypropionate (3HP) is an attractive platform chemical, serving as a precursor to a variety of commodity chemicals like acrylate and acrylamide, as well as a monomer of a biodegradable plastic. To establish a sustainable way to produce these commercially important chemicals and materials, fermentative production of 3HP is widely investigated in recent years. It is reported that 3HP can be produced from several intermediates, such as glycerol, malonyl-CoA, and β-alanine. Among all these biosynthetic routes, the malonyl-CoA pathway has some distinct advantages, including a broad feedstock spectrum, thermodynamic feasibility, and redox neutrality. To date, this pathway has been successfully constructed in various species including Escherichia coli, yeast and cyanobacteria, and optimized through carbon flux redirection, enzyme screening and engineering, and an increasing supply of energy and cofactors, resulting in significantly enhanced 3HP titer up to 40 g/L. These results show the feasibility of commercial manufacturing of 3HP and its derivatives in the future.
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Affiliation(s)
- Changshui Liu
- a CAS Key Lab of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.,b Institute of Oceanology , Chinese Academy of Sciences , Qingdao , China
| | - Yamei Ding
- b Institute of Oceanology , Chinese Academy of Sciences , Qingdao , China
| | - Mo Xian
- a CAS Key Lab of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
| | - Min Liu
- a CAS Key Lab of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
| | - Huizhou Liu
- a CAS Key Lab of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
| | - Qingjun Ma
- b Institute of Oceanology , Chinese Academy of Sciences , Qingdao , China
| | - Guang Zhao
- a CAS Key Lab of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
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11
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Loder AJ, Zeldes BM, Conway JM, Counts JA, Straub CT, Khatibi PA, Lee LL, Vitko NP, Keller MW, Rhaesa AM, Rubinstein GM, Scott IM, Lipscomb GL, Adams MW, Kelly RM. Extreme Thermophiles as Metabolic Engineering Platforms: Strategies and Current Perspective. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Andrew J. Loder
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Benjamin M. Zeldes
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Jonathan M. Conway
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - James A. Counts
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Christopher T. Straub
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Piyum A. Khatibi
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Laura L. Lee
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Nicholas P. Vitko
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Matthew W. Keller
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Amanda M. Rhaesa
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Gabe M. Rubinstein
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Israel M. Scott
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Gina L. Lipscomb
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Michael W.W. Adams
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Robert M. Kelly
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
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12
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Reaction kinetic analysis of the 3-hydroxypropionate/4-hydroxybutyrate CO 2 fixation cycle in extremely thermoacidophilic archaea. Metab Eng 2016; 38:446-463. [PMID: 27771364 DOI: 10.1016/j.ymben.2016.10.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/07/2016] [Accepted: 10/17/2016] [Indexed: 12/21/2022]
Abstract
The 3-hydroxypropionate/4-hydroxybutyrate (3HP/4HB) cycle fixes CO2 in extremely thermoacidophilic archaea and holds promise for metabolic engineering because of its thermostability and potentially rapid pathway kinetics. A reaction kinetics model was developed to examine the biological and biotechnological attributes of the 3HP/4HB cycle as it operates in Metallosphaera sedula, based on previous information as well as on kinetic parameters determined here for recombinant versions of five of the cycle enzymes (malonyl-CoA/succinyl-CoA reductase, 3-hydroxypropionyl-CoA synthetase, 3-hydroxypropionyl-CoA dehydratase, acryloyl-CoA reductase, and succinic semialdehyde reductase). The model correctly predicted previously observed features of the cycle: the 35-65% split of carbon flux through the acetyl-CoA and succinate branches, the high abundance and relative ratio of acetyl-CoA/propionyl-CoA carboxylase (ACC) and MCR, and the significance of ACC and hydroxybutyryl-CoA synthetase (HBCS) as regulated control points for the cycle. The model was then used to assess metabolic engineering strategies for incorporating CO2 into chemical intermediates and products of biotechnological importance: acetyl-CoA, succinate, and 3-hydroxypropionate.
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13
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Lian H, Zeldes BM, Lipscomb GL, Hawkins AB, Han Y, Loder AJ, Nishiyama D, Adams MWW, Kelly RM. Ancillary contributions of heterologous biotin protein ligase and carbonic anhydrase for CO 2 incorporation into 3-hydroxypropionate by metabolically engineered Pyrococcus furiosus. Biotechnol Bioeng 2016; 113:2652-2660. [PMID: 27315782 DOI: 10.1002/bit.26033] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/11/2016] [Accepted: 06/05/2016] [Indexed: 12/18/2022]
Abstract
Acetyl-Coenzyme A carboxylase (ACC), malonyl-CoA reductase (MCR), and malonic semialdehyde reductase (MRS) convert HCO3- and acetyl-CoA into 3-hydroxypropionate (3HP) in the 3-hydroxypropionate/4-hydroxybutyrate carbon fixation cycle resident in the extremely thermoacidophilic archaeon Metallosphaera sedula. These three enzymes, when introduced into the hyperthermophilic archaeon Pyrococcus furiosus, enable production of 3HP from maltose and CO2 . Sub-optimal function of ACC was hypothesized to be limiting for production of 3HP, so accessory enzymes carbonic anhydrase (CA) and biotin protein ligase (BPL) from M. sedula were produced recombinantly in Escherichia coli to assess their function. P. furiosus lacks a native, functional CA, while the M. sedula CA (Msed_0390) has a specific activity comparable to other microbial versions of this enzyme. M. sedula BPL (Msed_2010) was shown to biotinylate the β-subunit (biotin carboxyl carrier protein) of the ACC in vitro. Since the native BPLs in E. coli and P. furiosus may not adequately biotinylate the M. sedula ACC, the carboxylase was produced in P. furiosus by co-expression with the M. sedula BPL. The baseline production strain, containing only the ACC, MCR, and MSR, grown in a CO2 -sparged bioreactor reached titers of approximately 40 mg/L 3HP. Strains in which either the CA or BPL accessory enzyme from M. sedula was added to the pathway resulted in improved titers, 120 or 370 mg/L, respectively. The addition of both M. sedula CA and BPL, however, yielded intermediate titers of 3HP (240 mg/L), indicating that the effects of CA and BPL on the engineered 3HP pathway were not additive, possible reasons for which are discussed. While further efforts to improve 3HP production by regulating gene dosage, improving carbon flux and optimizing bioreactor operation are needed, these results illustrate the ancillary benefits of accessory enzymes for incorporating CO2 into 3HP production in metabolically engineered P. furiosus, and hint at the important role that CA and BPL likely play in the native 3HP/4HB pathway in M. sedula. Biotechnol. Bioeng. 2016;113: 2652-2660. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Hong Lian
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Benjamin M Zeldes
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Gina L Lipscomb
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
| | - Aaron B Hawkins
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Yejun Han
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Andrew J Loder
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Declan Nishiyama
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
| | - Robert M Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27587.
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Ye Z, Li X, Cheng Y, Liu Z, Tan G, Zhu F, Fu S, Deng Z, Liu T. Evaluation of 3-hydroxypropionate biosynthesis in vitro by partial introduction of the 3-hydroxypropionate/4-hydroxybutyrate cycle from Metallosphaera sedula. J Ind Microbiol Biotechnol 2016; 43:1313-21. [PMID: 27300329 PMCID: PMC4983293 DOI: 10.1007/s10295-016-1793-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/31/2016] [Indexed: 01/03/2023]
Abstract
The chemical 3-hydroxypropionate (3HP) is an important starting reagent for the commercial synthesis of specialty chemicals. In this study, a part of the 3-hydroxypropionate/4-hydroxybutyrate cycle from Metallosphaera sedula was utilized for 3HP production. To study the basic biochemistry of this pathway, an in vitro-reconstituted system was established using acetyl-CoA as the substrate for the kinetic analysis of this system. The results indicated that 3HP formation was sensitive to acetyl-CoA carboxylase and malonyl-CoA reductase, but not malonate semialdehyde reductase. Also, the competition between 3HP formation and fatty acid production was analyzed both in vitro and in vivo. This study has highlighted how metabolic flux is controlled by different catalytic components. We believe that this reconstituted system would be valuable for understanding 3HP biosynthesis pathway and for future engineering studies to enhance 3HP production.
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Affiliation(s)
- Ziling Ye
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Xiaowei Li
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Yongbo Cheng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Zhijie Liu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Gaoyi Tan
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Fayin Zhu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China
| | - Shuai Fu
- J1 Biotech, Co., Ltd, Wuhan, 430075, People's Republic of China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China.,Hubei Engineering Laboratory for Synthetic Microbiology, Wuhan Institute of Biotechnology, Wuhan, 430075, People's Republic of China.,The State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Tiangang Liu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People's Republic of China. .,Hubei Engineering Laboratory for Synthetic Microbiology, Wuhan Institute of Biotechnology, Wuhan, 430075, People's Republic of China. .,Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan, 430068, People's Republic of China.
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15
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Schut GJ, Lipscomb GL, Nguyen DMN, Kelly RM, Adams MWW. Heterologous Production of an Energy-Conserving Carbon Monoxide Dehydrogenase Complex in the Hyperthermophile Pyrococcus furiosus. Front Microbiol 2016; 7:29. [PMID: 26858706 PMCID: PMC4731540 DOI: 10.3389/fmicb.2016.00029] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/11/2016] [Indexed: 11/13/2022] Open
Abstract
Carbon monoxide (CO) is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus, which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a CO dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na+/H+ antiporter module. This complex oxidizes CO, evolves CO2 and H2, and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein we used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus, which grows optimally at 100°C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H2 at 80°C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms.
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Affiliation(s)
- Gerrit J Schut
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens GA, USA
| | - Gina L Lipscomb
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens GA, USA
| | - Diep M N Nguyen
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens GA, USA
| | - Robert M Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh NC, USA
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens GA, USA
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17
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Alissandratos A, Easton CJ. Biocatalysis for the application of CO2 as a chemical feedstock. Beilstein J Org Chem 2015; 11:2370-87. [PMID: 26734087 PMCID: PMC4685893 DOI: 10.3762/bjoc.11.259] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/20/2015] [Indexed: 11/23/2022] Open
Abstract
Biocatalysts, capable of efficiently transforming CO2 into other more reduced forms of carbon, offer sustainable alternatives to current oxidative technologies that rely on diminishing natural fossil-fuel deposits. Enzymes that catalyse CO2 fixation steps in carbon assimilation pathways are promising catalysts for the sustainable transformation of this safe and renewable feedstock into central metabolites. These may be further converted into a wide range of fuels and commodity chemicals, through the multitude of known enzymatic reactions. The required reducing equivalents for the net carbon reductions may be drawn from solar energy, electricity or chemical oxidation, and delivered in vitro or through cellular mechanisms, while enzyme catalysis lowers the activation barriers of the CO2 transformations to make them more energy efficient. The development of technologies that treat CO2-transforming enzymes and other cellular components as modules that may be assembled into synthetic reaction circuits will facilitate the use of CO2 as a renewable chemical feedstock, greatly enabling a sustainable carbon bio-economy.
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Affiliation(s)
| | - Christopher J Easton
- Research School of Chemistry, Australian National University, Canberra ACT 2601, Australia
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18
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Zeldes BM, Keller MW, Loder AJ, Straub CT, Adams MWW, Kelly RM. Extremely thermophilic microorganisms as metabolic engineering platforms for production of fuels and industrial chemicals. Front Microbiol 2015; 6:1209. [PMID: 26594201 PMCID: PMC4633485 DOI: 10.3389/fmicb.2015.01209] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/19/2015] [Indexed: 01/06/2023] Open
Abstract
Enzymes from extremely thermophilic microorganisms have been of technological interest for some time because of their ability to catalyze reactions of industrial significance at elevated temperatures. Thermophilic enzymes are now routinely produced in recombinant mesophilic hosts for use as discrete biocatalysts. Genome and metagenome sequence data for extreme thermophiles provide useful information for putative biocatalysts for a wide range of biotransformations, albeit involving at most a few enzymatic steps. However, in the past several years, unprecedented progress has been made in establishing molecular genetics tools for extreme thermophiles to the point that the use of these microorganisms as metabolic engineering platforms has become possible. While in its early days, complex metabolic pathways have been altered or engineered into recombinant extreme thermophiles, such that the production of fuels and chemicals at elevated temperatures has become possible. Not only does this expand the thermal range for industrial biotechnology, it also potentially provides biodiverse options for specific biotransformations unique to these microorganisms. The list of extreme thermophiles growing optimally between 70 and 100°C with genetic toolkits currently available includes archaea and bacteria, aerobes and anaerobes, coming from genera such as Caldicellulosiruptor, Sulfolobus, Thermotoga, Thermococcus, and Pyrococcus. These organisms exhibit unusual and potentially useful native metabolic capabilities, including cellulose degradation, metal solubilization, and RuBisCO-free carbon fixation. Those looking to design a thermal bioprocess now have a host of potential candidates to choose from, each with its own advantages and challenges that will influence its appropriateness for specific applications. Here, the issues and opportunities for extremely thermophilic metabolic engineering platforms are considered with an eye toward potential technological advantages for high temperature industrial biotechnology.
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Affiliation(s)
- Benjamin M Zeldes
- Department of Chemical and Biomolecular Engineering, North Carolina State University Raleigh, NC, USA
| | - Matthew W Keller
- Department of Biochemistry and Molecular Biology, University of Georgia Athens, GA, USA
| | - Andrew J Loder
- Department of Chemical and Biomolecular Engineering, North Carolina State University Raleigh, NC, USA
| | - Christopher T Straub
- Department of Chemical and Biomolecular Engineering, North Carolina State University Raleigh, NC, USA
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia Athens, GA, USA
| | - Robert M Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University Raleigh, NC, USA
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Metabolic engineering of cyanobacteria for photosynthetic 3-hydroxypropionic acid production from CO2 using Synechococcus elongatus PCC 7942. Metab Eng 2015; 31:163-70. [DOI: 10.1016/j.ymben.2015.08.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 04/16/2015] [Accepted: 08/05/2015] [Indexed: 02/04/2023]
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Alcohol Selectivity in a Synthetic Thermophilic n-Butanol Pathway Is Driven by Biocatalytic and Thermostability Characteristics of Constituent Enzymes. Appl Environ Microbiol 2015; 81:7187-200. [PMID: 26253677 DOI: 10.1128/aem.02028-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 07/29/2015] [Indexed: 02/06/2023] Open
Abstract
n-Butanol is generated as a natural product of metabolism by several microorganisms, but almost all grow at mesophilic temperatures. A synthetic pathway for n-butanol production from acetyl coenzyme A (acetyl-CoA) that functioned at 70°C was assembled in vitro from enzymes recruited from thermophilic bacteria to inform efforts for engineering butanol production into thermophilic hosts. Recombinant versions of eight thermophilic enzymes (β-ketothiolase [Thl], 3-hydroxybutyryl-CoA dehydrogenase [Hbd], and 3-hydroxybutyryl-CoA dehydratase [Crt] from Caldanaerobacter subterraneus subsp. tengcongensis; trans-2-enoyl-CoA reductase [Ter] from Spirochaeta thermophila; bifunctional acetaldehyde dehydrogenase/alcohol dehydrogenase [AdhE] from Clostridium thermocellum; and AdhE, aldehyde dehydrogenase [Bad], and butanol dehydrogenase [Bdh] from Thermoanaerobacter sp. strain X514) were utilized to examine three possible pathways for n-butanol. These pathways differed in the two steps required to convert butyryl-CoA to n-butanol: Thl-Hbd-Crt-Ter-AdhE (C. thermocellum), Thl-Hbd-Crt-Ter-AdhE (Thermoanaerobacter X514), and Thl-Hbd-Crt-Ter-Bad-Bdh. n-Butanol was produced at 70°C, but with different amounts of ethanol as a coproduct, because of the broad substrate specificities of AdhE, Bad, and Bdh. A reaction kinetics model, validated via comparison to in vitro experiments, was used to determine relative enzyme ratios needed to maximize n-butanol production. By using large relative amounts of Thl and Hbd and small amounts of Bad and Bdh, >70% conversion to n-butanol was observed in vitro, but with a 60% decrease in the predicted pathway flux. With more-selective hypothetical versions of Bad and Bdh, >70% conversion to n-butanol is predicted, with a 19% increase in pathway flux. Thus, more-selective thermophilic versions of Bad, Bdh, and AdhE are needed to fully exploit biocatalytic n-butanol production at elevated temperatures.
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A hybrid synthetic pathway for butanol production by a hyperthermophilic microbe. Metab Eng 2014; 27:101-106. [PMID: 25461832 DOI: 10.1016/j.ymben.2014.11.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 10/04/2014] [Accepted: 11/12/2014] [Indexed: 01/19/2023]
Abstract
Biologically produced alcohols are of great current interest for renewable solvents and liquid transportation fuels. While bioethanol is now produced on a massive scale, butanol has superior fuel characteristics and an additional value as a solvent and chemical feedstock. Butanol production has been demonstrated at ambient temperatures in metabolically-engineered mesophilic organisms, but the ability to engineer a microbe for in vivo high-temperature production of commodity chemicals has several distinct advantages. These include reduced contamination risk, facilitated removal of volatile products, and a wide temperature range to modulate and balance both the engineered pathway and the host׳s metabolism. We describe a synthetic metabolic pathway assembled from genes obtained from three different sources for conversion of acetyl-CoA to 1-butanol, and 1-butanol generation from glucose was demonstrated near 70°C in a microorganism that grows optimally near 100°C. The module could also be used in thermophiles capable of degrading plant biomass.
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Single gene insertion drives bioalcohol production by a thermophilic archaeon. Proc Natl Acad Sci U S A 2014; 111:17618-23. [PMID: 25368184 DOI: 10.1073/pnas.1413789111] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bioethanol production is achieved by only two metabolic pathways and only at moderate temperatures. Herein a fundamentally different synthetic pathway for bioalcohol production at 70 °C was constructed by insertion of the gene for bacterial alcohol dehydrogenase (AdhA) into the archaeon Pyrococcus furiosus. The engineered strain converted glucose to ethanol via acetate and acetaldehyde, catalyzed by the host-encoded aldehyde ferredoxin oxidoreductase (AOR) and heterologously expressed AdhA, in an energy-conserving, redox-balanced pathway. Furthermore, the AOR/AdhA pathway also converted exogenously added aliphatic and aromatic carboxylic acids to the corresponding alcohol using glucose, pyruvate, and/or hydrogen as the source of reductant. By heterologous coexpression of a membrane-bound carbon monoxide dehydrogenase, CO was used as a reductant for converting carboxylic acids to alcohols. Redirecting the fermentative metabolism of P. furiosus through strategic insertion of foreign genes creates unprecedented opportunities for thermophilic bioalcohol production. Moreover, the AOR/AdhA pathway is a potentially game-changing strategy for syngas fermentation, especially in combination with carbon chain elongation pathways.
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