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Heffernan JK, Valgepea K, de Souza Pinto Lemgruber R, Casini I, Plan M, Tappel R, Simpson SD, Köpke M, Nielsen LK, Marcellin E. Enhancing CO 2-Valorization Using Clostridium autoethanogenum for Sustainable Fuel and Chemicals Production. Front Bioeng Biotechnol 2020; 8:204. [PMID: 32292775 PMCID: PMC7135887 DOI: 10.3389/fbioe.2020.00204] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 03/02/2020] [Indexed: 01/02/2023] Open
Abstract
Acetogenic bacteria can convert waste gases into fuels and chemicals. Design of bioprocesses for waste carbon valorization requires quantification of steady-state carbon flows. Here, steady-state quantification of autotrophic chemostats containing Clostridium autoethanogenum grown on CO2 and H2 revealed that captured carbon (460 ± 80 mmol/gDCW/day) had a significant distribution to ethanol (54 ± 3 C-mol% with a 2.4 ± 0.3 g/L titer). We were impressed with this initial result, but also observed limitations to biomass concentration and growth rate. Metabolic modeling predicted culture performance and indicated significant metabolic adjustments when compared to fermentation with CO as the carbon source. Moreover, modeling highlighted flux to pyruvate, and subsequently reduced ferredoxin, as a target for improving CO2 and H2 fermentation. Supplementation with a small amount of CO enabled co-utilization with CO2, and enhanced CO2 fermentation performance significantly, while maintaining an industrially relevant product profile. Additionally, the highest specific flux through the Wood-Ljungdahl pathway was observed during co-utilization of CO2 and CO. Furthermore, the addition of CO led to superior CO2-valorizing characteristics (9.7 ± 0.4 g/L ethanol with a 66 ± 2 C-mol% distribution, and 540 ± 20 mmol CO2/gDCW/day). Similar industrial processes are commercial or currently being scaled up, indicating CO-supplemented CO2 and H2 fermentation has high potential for sustainable fuel and chemical production. This work also provides a reference dataset to advance our understanding of CO2 gas fermentation, which can contribute to mitigating climate change.
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Affiliation(s)
- James K. Heffernan
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Saint Lucia, QLD, Australia
| | - Kaspar Valgepea
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Saint Lucia, QLD, Australia
- ERA Chair in Gas Fermentation Technologies, Institute of Technology, University of Tartu, Tartu, Estonia
| | | | - Isabella Casini
- Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Manuel Plan
- Queensland Node of Metabolomics Australia, The University of Queensland, Saint Lucia, QLD, Australia
| | | | | | | | - Lars K. Nielsen
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Saint Lucia, QLD, Australia
- Queensland Node of Metabolomics Australia, The University of Queensland, Saint Lucia, QLD, Australia
| | - Esteban Marcellin
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Saint Lucia, QLD, Australia
- Queensland Node of Metabolomics Australia, The University of Queensland, Saint Lucia, QLD, Australia
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LaBelle EV, Marshall CW, May HD. Microbiome for the Electrosynthesis of Chemicals from Carbon Dioxide. Acc Chem Res 2020; 53:62-71. [PMID: 31809012 DOI: 10.1021/acs.accounts.9b00522] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The price for renewable electricity is rapidly decreasing, and the availability of such energy is expected to increase in the coming years. This is a welcomed outcome considering that mitigation of climate disruption due to the use of fossil carbon is reaching a critical stage. However, the economy will remain dependent on carbon-based chemicals and the problem of electricity storage persists. Therefore, the development of electrosynthetic processes that convert electricity and CO2 into chemicals and energy dense fuels, perhaps even food, would be desirable. Electrochemistry has been applied to the manufacture of many valuable products and at a large industrial scale, but it is difficult to produce multicarbon chemicals from CO2 by chemistry alone. Being that the biological world possesses expertise at the construction of C-C bonds, it is being examined in conjunction with electrochemistry to discover new ways of synthesizing chemicals from electricity and CO2. One approach is microbial electrosynthesis. This Account describes the development of a microbial electrosynthesis system by the authors. A biocathode consisting of a carbon-based electrode and a microbial community produced short chain fatty acids, primarily acetate. The device works by electrolysis of water, but microbes facilitate electron transfer from the cathode while reducing CO2 by the Wood-Ljungdahl pathway possessed by an Acetobacterium sp. While this acetogenic microorganism dominates the microbiome growing on the cathode surface, 13 total species of microbes overall were ecologically selected on the cathode and genomes for each have been assembled. The combined species may contribute to the stability of the microbiome, a common feature of naturally selected microbial communities. The microbial electrosynthesis system was demonstrated to operate continuously at a cathode for more than 2 years and could also be used with intermittent power, thus demonstrating the stability of the microbiome living at the cathode. In addition to the description of reactor design and startup procedures, the possible mechanisms of electron transfer are described in this Account. While mysteries remain to be solved, much evidence indicates that the microbiome may facilitate electron transfer by supplying catalyst(s) external to the bacterial cells and onto the cathode surface. This may be in the form of a hydrogen-producing catalyst that enhances hydrogen generation by an inert carbon-based electrode. Through the enrichment of the electrosynthetic microbiome along with several modifications in reactor design and operation, the productivity and efficiency were improved. In addition to the intrinsic value of the current products, coupling the process with a secondary stage might be used to produce more valuable products from the acetic acid stream such as lipids, biocrude oil, or higher value food supplements. Alternatively, additional work on the mechanism of electron transfer, reactor design/operation, and modification of the microbes through synthetic biology, particularly to enhance carbon efficiency into higher value chemicals, are the needed next steps to advance microbial electrosynthesis so that it may be used to transform renewable electrons and CO2 directly into products and help solve the problem of climate disruption.
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Affiliation(s)
- Edward V. LaBelle
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Christopher W. Marshall
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Harold D. May
- Department of Microbiology & Immunology, Hollings Marine Laboratory, Medical University of South Carolina, Charleston, South Carolina 29412, United States
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Yang H, Zhang C, Lai N, Huang B, Fei P, Ding D, Hu P, Gu Y, Wu H. Efficient isopropanol biosynthesis by engineered Escherichia coli using biologically produced acetate from syngas fermentation. BIORESOURCE TECHNOLOGY 2020; 296:122337. [PMID: 31727559 DOI: 10.1016/j.biortech.2019.122337] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 05/23/2023]
Abstract
The shortage of food based feedstocks is a challenge in industrial biomanufacturing. In this study, genetically modified Escherichia coli strains were used to produce isopropanol as the mainly product from acetate, a cost-effective nonfood-based substrate. The isopropanol biosynthesis pathway was constructed by combining genes from Clostridium acetobutylicum (thlA, adc), E. coli (atoDA) and Clostridium beijerinckii (adh). E. coli MG1655 harboring the isopropanol biosynthesis pathway successfully produced isopropanol and low amounts of acetone from pure acetate. The enhancement of the acetate assimilation pathway coupled with cofactor engineering strategy further improved the production of isopropanol to 18.5 mM with a yield of 0.26 mol/mol. With simple treatment, two kinds of biologically produced acetate were utilized to generate 16.7 and 24.5 mM isopropanol with yields of 0.25 and 0.56 mol/mol, respectively. Engineered E. coli with an optimized isopropanol biosynthesis pathway can efficiently utilize biologically produced acetate to synthesize isopropanol.
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Affiliation(s)
- Hao Yang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Can Zhang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ningyu Lai
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Bing Huang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Peng Fei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Dawei Ding
- Shanghai GTL Biotech Co., Ltd. 1688 North Guoquan Road, Shanghai 200438, China
| | - Peng Hu
- Shanghai GTL Biotech Co., Ltd. 1688 North Guoquan Road, Shanghai 200438, China
| | - Yang Gu
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hui Wu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China; Key Laboratory of Bio-based Material Engineering of China National Light Industry Council, 130 Meilong Road, Shanghai 200237, China; Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.
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Emerson DF, Stephanopoulos G. Limitations in converting waste gases to fuels and chemicals. Curr Opin Biotechnol 2019; 59:39-45. [DOI: 10.1016/j.copbio.2019.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 01/29/2019] [Accepted: 02/04/2019] [Indexed: 12/22/2022]
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Sun X, Atiyeh HK, Huhnke RL, Tanner RS. Syngas fermentation process development for production of biofuels and chemicals: A review. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biteb.2019.100279] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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57
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Zeng AP. New bioproduction systems for chemicals and fuels: Needs and new development. Biotechnol Adv 2019; 37:508-518. [DOI: 10.1016/j.biotechadv.2019.01.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/04/2019] [Accepted: 01/05/2019] [Indexed: 11/17/2022]
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Huang B, Fang G, Wu H, Sun J, Li Z, Ye Q. Efficient Biosynthesis of Succinate from Paper Mill Wastewater by Engineered Escherichia coli. Appl Biochem Biotechnol 2019; 189:1195-1208. [PMID: 31222619 DOI: 10.1007/s12010-019-03066-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/07/2019] [Indexed: 02/06/2023]
Abstract
A large amount of wastewater containing various organic compounds is generated in the paper-making industry. Therefore, the re-utilization of wastewater from paper-making is of great importance. In this study, acetic acid and formic acid, the dominant inhibitors existing in the paper mill wastewater, were used to produce succinate by metabolically engineered Escherichia coli strains, HB04(pTrc99a-gltA) and HB04(pTrc99a-gltA, pBAD33-Trc-fdh). The distilled paper mill wastewater could be utilized and transformed directly to succinate efficiently. However, the utilization of acetate was inhibited dramatically using raw paper mill wastewater. After adsorption by activate carbon, the acetate consumption and succinate production were improved significantly. In the resting cells experiment with high cell density (50 OD600), acetate was consumed completely and the titer of succinate reached 65.44 mM in 6 h. These results showed that the metabolically engineered E. coli strains had great potential to utilize acetic acid in the paper mill wastewater for succinate biosynthesis.
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Affiliation(s)
- Bing Huang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Guochen Fang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Hui Wu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai, 200237, China.,Key Laboratory of Bio-based Material Engineering of China National Light Industry Council, 130 Meilong Road, Shanghai, 200237, China
| | - Jibin Sun
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjian Airport Economic Area, Tianjin, 300308, China
| | - Zhimin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China. .,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai, 200237, China.
| | - Qin Ye
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
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Yang S, Li S, Jia X. Production of medium chain length polyhydroxyalkanoate from acetate by engineered Pseudomonas putida KT2440. ACTA ACUST UNITED AC 2019; 46:793-800. [DOI: 10.1007/s10295-019-02159-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 03/05/2019] [Indexed: 11/27/2022]
Abstract
Abstract
Pseudomonas putida was metabolically engineered to produce medium chain length polyhydroxyalkanoate (mcl-PHA) from acetate, a promising carbon source to achieve cost-effective microbial processes. As acetate is known to be harmful to cell growth, P. putida KT2440 was screened from three Pseudomonas strains (P. putida KT2440, P. putida NBRC14164, and P. aeruginosa PH1) as the host with the highest tolerance to 10 g/L of acetate in the medium. Subsequently, P. putida KT2440 was engineered by amplifying the acetate assimilation pathway, including overexpression of the acs (encoding acetyl-CoA synthetase) route and construction of the ackA-pta (encoding acetate kinase-phosphotransacetylase) pathway. The acs overexpressing P. putida KT2440 showed a remarkable increase of mcl-PHA titer (+ 92%), mcl-PHA yield (+ 50%), and cellular mcl-PHA content (+ 43%) compared with the wild-type P. putida KT2440, which indicated that acetate could be a potential substrate for biochemical production of mcl-PHA by engineered P. putida.
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Affiliation(s)
- Songyuan Yang
- 0000 0004 1761 2484 grid.33763.32 Department of Biological Engineering, School of Chemical Engineering and Technology Tianjin University 300072 Tianjin People’s Republic of China
- 0000 0004 1761 2484 grid.33763.32 Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology Tianjin University 300350 Tianjin People’s Republic of China
| | - Suhang Li
- 0000 0004 1761 2484 grid.33763.32 Department of Biological Engineering, School of Chemical Engineering and Technology Tianjin University 300072 Tianjin People’s Republic of China
- 0000 0004 1761 2484 grid.33763.32 Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology Tianjin University 300350 Tianjin People’s Republic of China
| | - Xiaoqiang Jia
- 0000 0004 1761 2484 grid.33763.32 Department of Biological Engineering, School of Chemical Engineering and Technology Tianjin University 300072 Tianjin People’s Republic of China
- 0000 0004 1761 2484 grid.33763.32 Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology Tianjin University 300350 Tianjin People’s Republic of China
- 0000 0004 1761 2484 grid.33763.32 Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) 300072 Tianjin People’s Republic of China
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Stoll IK, Boukis N, Neumann A, Ochsenreither K, Zevaco TA, Sauer J. The Complex Way to Sustainability: Petroleum-Based Processes versus Biosynthetic Pathways in the Formation of C4 Chemicals from Syngas. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b01123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I. Katharina Stoll
- Karlsruhe Institute of Technology, Institute of Catalysis Research and Technology (IKFT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Nikolaos Boukis
- Karlsruhe Institute of Technology, Institute of Catalysis Research and Technology (IKFT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Anke Neumann
- Technical Biology (TeBi), Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, 76128, Karlsruhe, Germany
| | - Katrin Ochsenreither
- Technical Biology (TeBi), Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, 76128, Karlsruhe, Germany
| | - Thomas A. Zevaco
- Karlsruhe Institute of Technology, Institute of Catalysis Research and Technology (IKFT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Jörg Sauer
- Karlsruhe Institute of Technology, Institute of Catalysis Research and Technology (IKFT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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de Souza Pinto Lemgruber R, Valgepea K, Tappel R, Behrendorff JB, Palfreyman RW, Plan M, Hodson MP, Simpson SD, Nielsen LK, Köpke M, Marcellin E. Systems-level engineering and characterisation of Clostridium autoethanogenum through heterologous production of poly-3-hydroxybutyrate (PHB). Metab Eng 2019; 53:14-23. [DOI: 10.1016/j.ymben.2019.01.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 01/03/2019] [Accepted: 01/05/2019] [Indexed: 11/26/2022]
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Tountas AA, Peng X, Tavasoli AV, Duchesne PN, Dingle TL, Dong Y, Hurtado L, Mohan A, Sun W, Ulmer U, Wang L, Wood TE, Maravelias CT, Sain MM, Ozin GA. Towards Solar Methanol: Past, Present, and Future. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801903. [PMID: 31016111 PMCID: PMC6468977 DOI: 10.1002/advs.201801903] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/12/2018] [Indexed: 05/24/2023]
Abstract
This work aims to provide an overview of producing value-added products affordably and sustainably from greenhouse gases (GHGs). Methanol (MeOH) is one such product, and is one of the most widely used chemicals, employed as a feedstock for ≈30% of industrial chemicals. The starting materials are analogous to those feeding natural processes: water, CO2, and light. Innovative technologies from this effort have global significance, as they allow GHG recycling, while providing society with a renewable carbon feedstock. Light, in the form of solar energy, assists the production process in some capacity. Various solar strategies of continually increasing technology readiness levels are compared to the commercial MeOH process, which uses a syngas feed derived from natural gas. These strategies include several key technologies, including solar-thermochemical, photochemical, and photovoltaic-electrochemical. Other solar-assisted technologies that are not yet commercial-ready are also discussed. The commercial-ready technologies are compared using a technoeconomic analysis, and the scalability of solar reactors is also discussed in the context of light-incorporating catalyst architectures and designs. Finally, how MeOH compares against other prospective products is briefly discussed, as well as the viability of the most promising solar MeOH strategy in an international context.
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Affiliation(s)
- Athanasios A. Tountas
- Department of Chemical Engineering and Applied ChemistryUniversity of Toronto200 College StreetTorontoONM5S 3E5Canada
| | - Xinyue Peng
- Department of Chemical and Biological EngineeringUniversity of Wisconsin–Madison1415 Engineering DriveMadisonWI53706USA
| | - Alexandra V. Tavasoli
- Department of Materials Science and EngineeringUniversity of Toronto184 College StTorontoONM5S 3E4Canada
| | - Paul N. Duchesne
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Thomas L. Dingle
- Department of Materials Science and EngineeringUniversity of Toronto184 College StTorontoONM5S 3E4Canada
| | - Yuchan Dong
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Lourdes Hurtado
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Abhinav Mohan
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Wei Sun
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Ulrich Ulmer
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Lu Wang
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Thomas E. Wood
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
| | - Christos T. Maravelias
- Department of Chemical and Biological EngineeringUniversity of Wisconsin–Madison1415 Engineering DriveMadisonWI53706USA
| | - Mohini M. Sain
- Department of Chemical Engineering and Applied ChemistryUniversity of Toronto200 College StreetTorontoONM5S 3E5Canada
- Department of Mechanical and Industrial EngineeringUniversity of Toronto5 King's College RoadTorontoONM5S 3G8Canada
| | - Geoffrey A. Ozin
- Department of ChemistryUniversity of Toronto80 St. George StreetTorontoOntarioM5S 3H6Canada
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Making the case for edible microorganisms as an integral part of a more sustainable and resilient food production system. Food Secur 2019. [DOI: 10.1007/s12571-019-00912-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Oh HJ, Kim KY, Lee KM, Lee SM, Gong G, Oh MK, Um Y. Enhanced butyric acid production using mixed biomass of brown algae and rice straw by Clostridium tyrobutyricum ATCC25755. BIORESOURCE TECHNOLOGY 2019; 273:446-453. [PMID: 30469134 DOI: 10.1016/j.biortech.2018.11.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
A brown alga Saccharina japonica and rice straw are attractive feedstock for microbial butyric acid production. However, inefficient fermentation of mannitol (a dominant component in S. japonica) and toxicity of inhibitors in lignocellulosic hydrolysate are limitations. This study demonstrated that mixed biomass with S. japonica and rice straw was effective in butyric acid production over those restrictions. Mannitol was consumed only when acetic acid was present. Notably, acetic acid was not produced but consumed along with mannitol. By mixing S. japonica and rice straw to take advantage of glucose and acetic acid in rice straw, Clostridium tyrobutyricum effectively consumed mannitol by utilizing acetic acid in hydrolysate and acetic acid derived from glucose with the enhanced butyric acid production. Furthermore, cell growth was restored owing to the decreased inhibitor concentration. The results demonstrate the potential of butyric acid production from mixed biomass of macroalgae/lignocellulose overcoming the drawbacks of single biomass.
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Affiliation(s)
- Hyun Ju Oh
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea; Department of Chemical and Biological Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul, Republic of Korea
| | - Ki-Yeon Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea; Clean Energy and Chemical Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Kyung Min Lee
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea
| | - Sun-Mi Lee
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea; Clean Energy and Chemical Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Gyeongtaek Gong
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea
| | - Min-Kyu Oh
- Department of Chemical and Biological Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul, Republic of Korea
| | - Youngsoon Um
- Clean Energy Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of Korea; Clean Energy and Chemical Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon, Republic of Korea.
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Metabolic engineering of Escherichia coli carrying the hybrid acetone-biosynthesis pathway for efficient acetone biosynthesis from acetate. Microb Cell Fact 2019; 18:6. [PMID: 30642338 PMCID: PMC6330746 DOI: 10.1186/s12934-019-1054-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/07/2019] [Indexed: 01/18/2023] Open
Abstract
Background The shortage of food based feedstocks has been one of the stumbling blocks in industrial biomanufacturing. The acetone bioproduction from the traditional acetone–butanol–ethanol fermentation is limited by the non-specificity of products and competitive utilization of food-based substrates. Using genetically modified Escherichia coli to produce acetone as sole product from the cost-effective non-food based substrates showed great potential to overcome these problems. Results A novel acetone biosynthetic pathway were constructed based on genes from Clostridium acetobutylicum (thlA encoding for thiolase, adc encoding for acetoacetate decarboxylase, ctfAB encoding for coenzyme A transferase) and Escherichia coli MG1655 (atoB encoding acetyl-CoA acetyltransferase, atoDA encoding for acetyl-CoA: acetoacetyl-CoA transferase subunit α and β). Among these constructs, one recombinant MG1655 derivative containing the hybrid pathway consisting of thlA, atoDA, and adc, produced the highest level of acetone from acetate. Reducing the gluconeogenesis pathway had little effect on acetone production, while blocking the TCA cycle by knocking out the icdA gene enhanced the yield of acetone significantly. As a result, acetone concentration increased up to 113.18 mM in 24 h by the resting cell culture coupling with gas-stripping methods. Conclusions An engineered E. coli strain with optimized hybrid acetone biosynthetic pathway can utilize acetate as substrate efficiently to synthesize acetone without other non-gas byproducts. It provides a potential method for industrial biomanufacturing of acetone by engineered E. coli strains from non-food based substrate. Electronic supplementary material The online version of this article (10.1186/s12934-019-1054-8) contains supplementary material, which is available to authorized users.
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Luo G, Jing Y, Lin Y, Zhang S, An D. A novel concept for syngas biomethanation by two-stage process: Focusing on the selective conversion of syngas to acetate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 645:1194-1200. [PMID: 30248844 DOI: 10.1016/j.scitotenv.2018.07.263] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 06/08/2023]
Abstract
Thermal gasification of nonrenewable and renewable sources produces syngas, containing CO, H2, CO2 and N2. Anaerobic conversion of syngas to CH4 is a promising way to replace natural gas. However, the high N2 content (>50%) in syngas would result in the low CH4 content in the biogas and CO in syngas also had serious inhibition on methanogens. The present study proposed a two-stage anaerobic process for syngas biomethanation, and syngas was first anaerobically converted to acetate by mixed culture, which could be further converted to methane easily without the negative effects of N2 and CO. The results showed that mesophilic condition was more suitable for the conversion of syngas to acetate compared to thermophilic and ambient conditions at pH 5.5 considering the higher acetate yield and syngas conversion rate. Although CO was efficiently converted at thermophilic condition, it was mostly converted to H2, which was then converted to acetate. CO was much easier to be converted compared to H2. Further study showed that pH 6.5 and 7.5 were optimal for selective conversion of syngas to acetate. The other products including butyrate and ethanol were also detected in relatively higher amounts at pH 4.5 and 9.5. Although pH 5.5 and 8.5 had relatively lower syngas conversion rates compared to pH 6.5 and 7.5, they might inhibit methanogens naturally without adding methane inhibitors. Finally, batch experiments showed that the acetate concentration had obvious inhibition on syngas conversion when the acetate concentration was higher than 2 g/L.
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Affiliation(s)
- Gang Luo
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433 Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Yuhang Jing
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433 Shanghai, China
| | - Yujin Lin
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433 Shanghai, China
| | - Shicheng Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433 Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Dong An
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433 Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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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.
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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
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Liebal UW, Blank LM, Ebert BE. CO 2 to succinic acid - Estimating the potential of biocatalytic routes. Metab Eng Commun 2018; 7:e00075. [PMID: 30197864 PMCID: PMC6127376 DOI: 10.1016/j.mec.2018.e00075] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/07/2018] [Accepted: 06/25/2018] [Indexed: 11/26/2022] Open
Abstract
Microbial carbon dioxide assimilation and conversion to chemical platform molecules has the potential to be developed as economic, sustainable processes. The carbon dioxide assimilation can proceed by a variety of natural pathways and recently even synthetic CO2 fixation routes have been designed. Early assessment of the performance of the different carbon fixation alternatives within biotechnological processes is desirable to evaluate their potential. Here we applied stoichiometric metabolic modeling based on physiological and process data to evaluate different process variants for the conversion of C1 carbon compounds to the industrial relevant platform chemical succinic acid. We computationally analyzed the performance of cyanobacteria, acetogens, methylotrophs, and synthetic CO2 fixation pathways in Saccharomyces cerevisiae in terms of production rates, product yields, and the optimization potential. This analysis provided insight into the economic feasibility and allowed to estimate the future industrial applicability by estimating overall production costs. With reported, or estimated data of engineered or wild type strains, none of the simulated microbial succinate production processes showed a performance allowing competitive production. The main limiting factors were identified as gas and photon transfer and metabolic activities whereas metabolic network structure was not restricting. In simulations with optimized parameters most process alternatives reached economically interesting values, hence, represent promising alternatives to sugar-based fermentations.
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Affiliation(s)
| | - Lars M. Blank
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany
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69
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Jiang Y, Jianxiong Zeng R. Expanding the product spectrum of value added chemicals in microbial electrosynthesis through integrated process design-A review. BIORESOURCE TECHNOLOGY 2018; 269:503-512. [PMID: 30174268 DOI: 10.1016/j.biortech.2018.08.101] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 08/23/2018] [Accepted: 08/24/2018] [Indexed: 06/08/2023]
Abstract
Microbial electrosynthesis (MES) is a novel microbial electrochemical technology proposed for chemicals production with the storage of sustainable energy. However, the practical application of MES is currently restricted by the limited low market value of products in one-step conversion process, mostly acetate. A theme that is pervasive throughout this review is the challenges associated with the expanded product spectrum. Several recent research efforts to improve acetate production, using novel reactor configuration, renewable power supply, and various 3-D cathode are summarized. The importance of genetic modification, two-step hybrid process, as well as input substrates other than CO2 are highlighted in this review as the future research paths for higher value chemicals production. At last, how to integrate MES with existing biochemicals processes is proposed. Definitely, more studies are encouraged to evaluate the overall performances and economic efficiency of these integrated process designs to make MES more competitive.
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Affiliation(s)
- Yong Jiang
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Raymond Jianxiong Zeng
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
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Abstract
Alarming changes in environmental conditions have prompted significant research into producing renewable commodities from sources other than fossil fuels. One such alternative is CO2, a determinate greenhouse gas with historically high atmospheric levels. If sequestered, CO2 could be used as a highly renewable feedstock for industrially relevant products and fuels. The vast majority of atmospheric CO2 fixation is accomplished by photosynthetic organisms, which have unfortunately proven difficult to utilize as chassis for industrial production. Nonphotosynthetic CO2 fixing microorganisms and pathways have recently attracted scientific and commercial interest. This Perspective will review promising alternate CO2 fixation strategies and their potential to supply microbially produced fuels and commodity chemicals, such as higher alcohols. Acetogenic fermentation and microbial electrosynthesis are the primary focuses of this review.
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Affiliation(s)
- Jake N Gonzales
- Plant Biology Graduate Group , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
| | - Morgan M Matson
- Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
| | - Shota Atsumi
- Plant Biology Graduate Group , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States.,Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
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Yaguchi A, Spagnuolo M, Blenner M. Engineering yeast for utilization of alternative feedstocks. Curr Opin Biotechnol 2018; 53:122-129. [DOI: 10.1016/j.copbio.2017.12.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/01/2017] [Accepted: 12/01/2017] [Indexed: 11/16/2022]
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Engineering NADH/NAD + ratio in Halomonas bluephagenesis for enhanced production of polyhydroxyalkanoates (PHA). Metab Eng 2018; 49:275-286. [PMID: 30219528 DOI: 10.1016/j.ymben.2018.09.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/12/2018] [Accepted: 09/12/2018] [Indexed: 11/20/2022]
Abstract
Halomonas bluephagenesis has been developed as a platform strain for the next generation industrial biotechnology (NGIB) with advantages of resistances to microbial contamination and high cell density growth (HCD), especially for production of polyhydroxyalkanoates (PHA) including poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). However, little is known about the mechanism behind PHA accumulation under oxygen limitation. This study for the first time found that H. bluephagenesis utilizes NADH instead of NADPH as a cofactor for PHB production, thus revealing the rare situation of enhanced PHA accumulation under oxygen limitation. To increase NADH/NAD+ ratio for enhanced PHA accumulation under oxygen limitation, an electron transport pathway containing electron transfer flavoprotein subunits α and β encoded by etf operon was blocked to increase NADH supply, leading to 90% PHB accumulation in the cell dry weight (CDW) of H. bluephagenesis compared with 84% by the wild type. Acetic acid, a cost-effective carbon source, was used together with glucose to balance the redox state and reduce inhibition on pyruvate metabolism, resulting in 22% more CDW and 94% PHB accumulation. The cellular redox state changes induced by the addition of acetic acid increased 3HV ratio in its copolymer PHBV from 4% to 8%, 4HB in its copolymer P34HB from 8% to 12%, respectively, by engineered H. bluephagenesis. The strategy of systematically modulation on the redox potential of H. bluephagenesis led to enhanced PHA accumulation and controllable monomer ratios in PHA copolymers under oxygen limitation, reducing energy consumption and scale-up complexity.
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73
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Wang G, Jia W, Chen N, Zhang K, Wang L, Lv P, He R, Wang M, Zhang D. A GFP-fusion coupling FACS platform for advancing the metabolic engineering of filamentous fungi. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:232. [PMID: 30159032 PMCID: PMC6109270 DOI: 10.1186/s13068-018-1223-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 08/06/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND The filamentous fungus Trichoderma reesei, the most widely used cellulase producer, also has promising applications in lignocellulose-based biorefinery: consolidated bioprocessing for the production of high value-added products. However, such applications are thwarted by the time-consuming metabolic engineering processes (design-build-test-learn cycle) for T. reesei, resulted from (i) the spore separation-mediated purification as the multinucleate hyphae, (ii) transformant screening for high expression levels since unavailable of episomal expression system, and (iii) cases of inexpressible heterologous proteins. RESULTS In this study, a GFP-fusion coupled fluorescence-activated cell sorting (FACS) platform was established to speed up the build and test process of the DBTL cycle, by enabling rapid selection for expressible heterologous genes and bypassing both laborious spore separation and transformant screening. Here, the feasibility of flow cytometry in analyzing and sorting T. reesei cells harboring GFP-fused expressible protein was proven, as well as the application of the platform for constitutive promoter strength evaluation. As a proof-of-concept, the platform was employed to construct the first T. reesei strain producing fatty alcohol, resulting in up to 2 mg hexadecanol being produced per gram biomass. Pathway construction was enabled through rapid selection of functional fatty acyl-CoA reductase encoding gene Tafar1 from three candidate genes and strains with high expression level from spore pools. As a result of using this method, the total costed time for the build and test cycle using T. reesei, subsequently, reduced by approx. 75% from 2 months to 2 weeks. CONCLUSION This study established the GFP-fusion coupling FACS platform and the first filamentous fungal fatty alcohol-producing cell factory, and demonstrated versatile applications of the platform in the metabolic engineering of filamentous fungi, which can be harnessed to potentially advance the application of filamentous fungi in lignocellulose-based biorefinery.
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Affiliation(s)
- Guokun Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Wendi Jia
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Na Chen
- Tangshan Academy of Agricultural Sciences, Tangshan, 063001 People’s Republic of China
| | - Ke Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Lixian Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Pin Lv
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Ronglin He
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Min Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
| | - Dongyuan Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People’s Republic of China
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Nazem-Bokaee H, Maranas CD. A Prospective Study on the Fermentation Landscape of Gaseous Substrates to Biorenewables Using Methanosarcina acetivorans Metabolic Model. Front Microbiol 2018; 9:1855. [PMID: 30197630 PMCID: PMC6117407 DOI: 10.3389/fmicb.2018.01855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/24/2018] [Indexed: 12/18/2022] Open
Abstract
The abundance of methane in shale gas and of other gases such as carbon monoxide, hydrogen, and carbon dioxide as chemical process byproducts has motivated the use of gas fermentation for bioproduction. Recent advances in metabolic engineering and synthetic biology allow for engineering of microbes metabolizing a variety of chemicals including gaseous feeds into a number of biorenewables and transportation liquid fuels. New computational tools enable the systematic exploration of all feasible conversion alternatives. Here we computationally assessed all thermodynamically feasible ways of co-utilizing CH4, CO, and CO2 using ferric as terminal electron acceptor for the production of all key precursor metabolites. We identified the thermodynamically feasible co-utilization ratio ranges of CH4, CO, and CO2 toward production of the target metabolite(s) as a function of ferric uptake. A revised version of the iMAC868 genome-scale metabolic model of Methanosarcina acetivorans was chosen to assess co-utilization of CH4, CO, and CO2 and their conversion into selected target products using the optStoic pathway design tool. This revised version contains the latest information on electron flow mechanisms by the methanogen while supplied with methane as the sole carbon source. The interplay between different gas co-utilization ratios and the energetics of reverse methanogenesis were also analyzed using the same metabolic model.
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Affiliation(s)
- Hadi Nazem-Bokaee
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
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Lehtinen T, Virtanen H, Santala S, Santala V. Production of alkanes from CO 2 by engineered bacteria. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:228. [PMID: 30151056 PMCID: PMC6102805 DOI: 10.1186/s13068-018-1229-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Microbial biosynthesis of alkanes is considered a promising method for the sustainable production of drop-in fuels and chemicals. Carbon dioxide would be an ideal carbon source for these production systems, but efficient production of long carbon chains from CO2 is difficult to achieve in a single organism. A potential solution is to employ acetogenic bacteria for the reduction of CO2 to acetate, and engineer a second organism to convert the acetate into long-chain hydrocarbons. RESULTS In this study, we demonstrate alkane production from CO2 by a system combining the acetogen Acetobacterium woodii and a non-native alkane producer Acinetobacter baylyi ADP1 engineered for alkane production. Nine synthetic two-step alkane biosynthesis pathways consisting of different aldehyde- and alkane-producing enzymes were combinatorically constructed and expressed in A. baylyi. The aldehyde-producing enzymes studied were AAR from Synechococcus elongatus, Acr1 from A. baylyi, and a putative dehydrogenase from Nevskia ramosa. The alkane-producing enzymes were ADOs from S. elongatus and Nostoc punctiforme, and CER1 from Arabidopsis thaliana. The performance of the pathways was evaluated with a twin-layer biosensor, which allowed the monitoring of both the intermediate (fatty aldehyde), and end product (alkane) formation. The highest alkane production, as indicated by the biosensor, was achieved with a pathway consisting of AAR and ADO from S. elongatus. The performance of this pathway was further improved by balancing the relative expression levels of the enzymes to limit the accumulation of the intermediate fatty aldehyde. Finally, the acetogen A. woodii was used to produce acetate from CO2 and H2, and the acetate was used for alkane production by the engineered A. baylyi, thereby leading to the net production of long-chain alkanes from CO2. CONCLUSIONS A modular system for the production of drop-in liquid fuels from CO2 was demonstrated. Among the studied synthetic pathways, the combination of ADO and AAR from S. elongatus was found to be the most efficient in heterologous alkane production in A. baylyi. Furthermore, limiting the accumulation of the fatty aldehyde intermediate was found to be beneficial for the alkane production. Nevertheless, the alkane productivity of the system remained low, representing a major challenge for future research.
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Affiliation(s)
- Tapio Lehtinen
- Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Henri Virtanen
- Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Suvi Santala
- Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Ville Santala
- Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, 33720 Tampere, Finland
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76
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Chen J, Li W, Zhang ZZ, Tan TW, Li ZJ. Metabolic engineering of Escherichia coli for the synthesis of polyhydroxyalkanoates using acetate as a main carbon source. Microb Cell Fact 2018; 17:102. [PMID: 29970091 PMCID: PMC6029019 DOI: 10.1186/s12934-018-0949-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 06/26/2018] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND High production cost of bioplastics polyhydroxyalkanoates (PHA) is a major obstacle to replace traditional petro-based plastics. To address the challenges, strategies towards upstream metabolic engineering and downstream fermentation optimizations have been continuously pursued. Given that the feedstocks especially carbon sources account up to a large portion of the production cost, it is of great importance to explore low cost substrates to manufacture PHA economically. RESULTS Escherichia coli was metabolically engineered to synthesize poly-3-hydroxybutyrate (P3HB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) using acetate as a main carbon source. Overexpression of phosphotransacetylase/acetate kinase pathway was shown to be an effective strategy for improving acetate assimilation and biopolymer production. The recombinant strain overexpressing phosphotransacetylase/acetate kinase and P3HB synthesis operon produced 1.27 g/L P3HB when grown on minimal medium supplemented with 10 g/L yeast extract and 5 g/L acetate in shake flask cultures. Further introduction succinate semialdehyde dehydrogenase, 4-hydroxybutyrate dehydrogenase, and CoA transferase lead to the accumulation of P3HB4HB, reaching a titer of 1.71 g/L with a 4-hydroxybutyrate monomer content of 5.79 mol%. When 1 g/L of α-ketoglutarate or citrate was added to the medium, P3HB4HB titer increased to 1.99 and 2.15 g/L, respectively. To achieve PHBV synthesis, acetate and propionate were simultaneously supplied and propionyl-CoA transferase was overexpressed to provide 3-hydroxyvalerate precursor. The resulting strain produced 0.33 g/L PHBV with a 3-hydroxyvalerate monomer content of 6.58 mol%. Further overexpression of propionate permease improved PHBV titer and 3-hydroxyvalerate monomer content to 1.09 g/L and 10.37 mol%, respectively. CONCLUSIONS The application of acetate as carbon source for microbial fermentation could reduce the consumption of food and agro-based renewable bioresources for biorefineries. Our proposed metabolic engineering strategies illustrate the feasibility for producing polyhydroxyalkanoates using acetate as a main carbon source. Overall, as an abundant and renewable resource, acetate would be developed into a cost-effective feedstock to achieve low cost production of chemicals, materials, and biofuels.
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Affiliation(s)
- Jing Chen
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Mailbox 53, No. 15 Beisanhuan Donglu, Chaoyang District, Beijing, 100029 China
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Wei Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Mailbox 53, No. 15 Beisanhuan Donglu, Chaoyang District, Beijing, 100029 China
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Zhao-Zhou Zhang
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Tian-Wei Tan
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Zheng-Jun Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Mailbox 53, No. 15 Beisanhuan Donglu, Chaoyang District, Beijing, 100029 China
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
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Spagnuolo M, Shabbir Hussain M, Gambill L, Blenner M. Alternative Substrate Metabolism in Yarrowia lipolytica. Front Microbiol 2018; 9:1077. [PMID: 29887845 PMCID: PMC5980982 DOI: 10.3389/fmicb.2018.01077] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 05/07/2018] [Indexed: 11/13/2022] Open
Abstract
Recent advances in genetic engineering capabilities have enabled the development of oleochemical producing strains of Yarrowia lipolytica. Much of the metabolic engineering effort has focused on pathway engineering of the product using glucose as the feedstock; however, alternative substrates, including various other hexose and pentose sugars, glycerol, lipids, acetate, and less-refined carbon feedstocks, have not received the same attention. In this review, we discuss recent work leading to better utilization of alternative substrates. This review aims to provide a comprehensive understanding of the current state of knowledge for alternative substrate utilization, suggest potential pathways identified through homology in the absence of prior characterization, discuss recent work that either identifies, endogenous or cryptic metabolism, and describe metabolic engineering to improve alternative substrate utilization. Finally, we describe the critical questions and challenges that remain for engineering Y. lipolytica for better alternative substrate utilization.
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Affiliation(s)
- Michael Spagnuolo
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States
| | - Murtaza Shabbir Hussain
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States
| | - Lauren Gambill
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States
- Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, United States
| | - Mark Blenner
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States
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Lim HG, Lee JH, Noh MH, Jung GY. Rediscovering Acetate Metabolism: Its Potential Sources and Utilization for Biobased Transformation into Value-Added Chemicals. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:3998-4006. [PMID: 29637770 DOI: 10.1021/acs.jafc.8b00458] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
One of the great advantages of microbial fermentation is the capacity to convert various carbon compounds into value-added chemicals. In this regard, there have been many efforts to engineer microorganisms to facilitate utilization of abundant carbon sources. Recently, the potential of acetate as a feedstock has been discovered; efforts have been made to produce various biochemicals from acetate based on understanding of its metabolism. In this review, we discuss the potential sources of acetate and summarized the recent progress to improve acetate utilization with microorganisms. Furthermore, we also describe representative studies that engineered microorganisms for the production of biochemicals from acetate.
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79
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Zhang JL, Peng YZ, Liu D, Liu H, Cao YX, Li BZ, Li C, Yuan YJ. Gene repression via multiplex gRNA strategy in Y. lipolytica. Microb Cell Fact 2018; 17:62. [PMID: 29678175 PMCID: PMC5910576 DOI: 10.1186/s12934-018-0909-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/13/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The oleaginous yeast Yarrowia lipolytica is a promising microbial cell factory due to their biochemical characteristics and native capacity to accumulate lipid-based chemicals. To create heterogenous biosynthesis pathway and manipulate metabolic flux in Y. lipolytica, numerous studies have been done for developing synthetic biology tools for gene regulation. CRISPR interference (CRISPRi), as an emerging technology, has been applied for specifically repressing genes of interest. RESULTS In this study, we established CRISPRi systems in Y. lipolytica based on four different repressors, that was DNase-deactivated Cpf1 (dCpf1) from Francisella novicida, deactivated Cas9 (dCas9) from Streptococcus pyogenes, and two fusion proteins (dCpf1-KRAB and dCas9-KRAB). Ten gRNAs that bound to different regions of gfp gene were designed and the results indicated that there was no clear correlation between the repression efficiency and targeting sites no matter which repressor protein was used. In order to rapidly yield strong gene repression, a multiplex gRNAs strategy based on one-step Golden-brick assembly technology was developed. High repression efficiency 85% (dCpf1) and 92% (dCas9) were achieved in a short time by making three different gRNAs towards gfp gene simultaneously, which avoided the need of screening effective gRNA loci in advance. Moreover, two genes interference including gfp and vioE and three genes repression including vioA, vioB and vioE in protodeoxy-violaceinic acid pathway were also realized. CONCLUSION Taken together, successful CRISPRi-mediated regulation of gene expression via four different repressors dCpf1, dCas9, dCpf1-KRAB and dCas9-KRAB in Y. lipolytica is achieved. And we demonstrate a multiplexed gRNA targeting strategy can efficiently achieve transcriptional simultaneous repression of several targeted genes and different sites of one gene using the one-step Golden-brick assembly. This timesaving method promised to be a potent transformative tool valuable for metabolic engineering, synthetic biology, and functional genomic studies of Y. lipolytica.
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Affiliation(s)
- Jin-lai Zhang
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Yang-Zi Peng
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Duo Liu
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Hong Liu
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Ying-Xiu Cao
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Bing-Zhi Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Chun Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Ying-Jin Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072 People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
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80
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Chen X, Cao Y, Li F, Tian Y, Song H. Enzyme-Assisted Microbial Electrosynthesis of Poly(3-hydroxybutyrate) via CO2 Bioreduction by Engineered Ralstonia eutropha. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00226] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Xiaoli Chen
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
| | - Yingxiu Cao
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
| | - Feng Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
| | - Yao Tian
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
| | - Hao Song
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People’s Republic of China
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81
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A two-stage biological gas to liquid transfer process to convert carbon dioxide into bioplastic. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.biteb.2018.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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82
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Oswald F, Stoll IK, Zwick M, Herbig S, Sauer J, Boukis N, Neumann A. Formic Acid Formation by Clostridium ljungdahlii at Elevated Pressures of Carbon Dioxide and Hydrogen. Front Bioeng Biotechnol 2018; 6:6. [PMID: 29484294 PMCID: PMC5816570 DOI: 10.3389/fbioe.2018.00006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/15/2018] [Indexed: 01/24/2023] Open
Abstract
Low productivities of bioprocesses using gaseous carbon and energy sources are usually caused by the low solubility of those gases (e.g., H2 and CO). It has been suggested that increasing the partial pressure of those gases will result in higher dissolved concentrations and should, therefore, be helpful to overcome this obstacle. Investigations of the late 1980s with mixtures of hydrogen and carbon monoxide showed inhibitory effects of carbon monoxide partial pressures above 0.8 bar. Avoiding any effects of carbon monoxide, we investigate growth and product formation of Clostridium ljungdahlii at absolute process pressures of 1, 4, and 7 bar in batch stirred tank reactor cultivations with carbon dioxide and hydrogen as sole gaseous carbon and energy source. With increasing process pressure, the product spectrum shifts from mainly acetic acid and ethanol to almost only formic acid at a total system pressure of 7 bar. On the other hand, no significant changes in overall product yield can be observed. By keeping the amount of substance flow rate constant instead of the volumetric gas feed rate when increasing the process pressure, we increased the overall product yield of 7.5 times of what has been previously reported in the literature. After 90 h of cultivation at a total pressure of 7 bar a total of 4 g L−1 of products is produced consisting of 82.7 % formic acid, 15.6 % acetic acid, and 1.7 % ethanol.
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Affiliation(s)
- Florian Oswald
- Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - I Katharina Stoll
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Michaela Zwick
- Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Sophia Herbig
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Jörg Sauer
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Nikolaos Boukis
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Anke Neumann
- Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
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83
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Huang B, Yang H, Fang G, Zhang X, Wu H, Li Z, Ye Q. Central pathway engineering for enhanced succinate biosynthesis from acetate in Escherichia coli. Biotechnol Bioeng 2018; 115:943-954. [PMID: 29278414 DOI: 10.1002/bit.26528] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 01/20/2023]
Abstract
Acetate, a non-food based substrate obtained from multiple biological and chemical ways, is now being paid great attention in bio-manufacturing and have a strong potential to compete with sugar-based carbon source. In this study, acetate can be efficiently converted to succinate by engineered Escherichia coli strains via the combination of several metabolic engineering strategies, including reducing OAA decarboxylation, engineering TCA cycle, enhancement of acetate assimilation pathway and increasing aerobic ATP supply through cofactor engineering. The engineered strain HB03(pTrc99a-gltA, pBAD33-Trc-fdh) accumulated 30.9 mM of succinate in 72 hr and the yield reached the maximum theoretical yield (∼0.50 mol/mol). In the resting-cell experiments, the yield of succinate in HB03(pTrc99a-gltA) and HB03(pTrc99a-gltA, pBAD33-Trc-fdh) dropped dramatically, although the productivity of succinate increased due to the high cell density. Further deletion of icdA, formed HB04(pTrc99a-gltA) and HB04(pTrc99a-gltA, pBAD33-Trc-fdh), increased the yield of succinate in the resting-cell experiments. The highest concentration of succinate achieved 194 mM and the yield reached 0.44 mol/mol in 16 hr by HB04(pTrc99a-gltA, pBAD33-Trc-fdh). The results showed the metabolically engineered E. coli strains have great potential to produce succinate from acetate.
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Affiliation(s)
- Bing Huang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Hao Yang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Guochen Fang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Xing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Hui Wu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China.,Key Laboratory of Bio-Based Material Engineering of China National Light Industry Council, Shanghai, China
| | - Zhimin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China
| | - Qin Ye
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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84
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85
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Noh MH, Lim HG, Woo SH, Song J, Jung GY. Production of itaconic acid from acetate by engineering acid-tolerant Escherichia coli
W. Biotechnol Bioeng 2017; 115:729-738. [DOI: 10.1002/bit.26508] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/10/2017] [Accepted: 11/30/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Myung Hyun Noh
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Sung Hwa Woo
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Jinyi Song
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
- School of Interdisciplinary Bioscience and Bioengineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
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86
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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: 54] [Impact Index Per Article: 7.7] [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.
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87
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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]
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88
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Lehtinen T, Efimova E, Tremblay PL, Santala S, Zhang T, Santala V. Production of long chain alkyl esters from carbon dioxide and electricity by a two-stage bacterial process. BIORESOURCE TECHNOLOGY 2017; 243:30-36. [PMID: 28651136 DOI: 10.1016/j.biortech.2017.06.073] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/12/2017] [Accepted: 06/13/2017] [Indexed: 05/19/2023]
Abstract
Microbial electrosynthesis (MES) is a promising technology for the reduction of carbon dioxide into value-added multicarbon molecules. In order to broaden the product profile of MES processes, we developed a two-stage process for microbial conversion of carbon dioxide and electricity into long chain alkyl esters. In the first stage, the carbon dioxide is reduced to organic compounds, mainly acetate, in a MES process by Sporomusa ovata. In the second stage, the liquid end-products of the MES process are converted to the final product by a second microorganism, Acinetobacter baylyi in an aerobic bioprocess. In this proof-of-principle study, we demonstrate for the first time the bacterial production of long alkyl esters (wax esters) from carbon dioxide and electricity as the sole sources of carbon and energy. The process holds potential for the efficient production of carbon-neutral chemicals or biofuels.
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Affiliation(s)
- Tapio Lehtinen
- Tampere University of Technology, Department of Chemistry and Bioengineering, Korkeakoulunkatu 8, 33720 Tampere, Finland.
| | - Elena Efimova
- Tampere University of Technology, Department of Chemistry and Bioengineering, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Pier-Luc Tremblay
- Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs.Lyngby, Denmark; School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China
| | - Suvi Santala
- Tampere University of Technology, Department of Chemistry and Bioengineering, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Tian Zhang
- Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs.Lyngby, Denmark; School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China
| | - Ville Santala
- Tampere University of Technology, Department of Chemistry and Bioengineering, Korkeakoulunkatu 8, 33720 Tampere, Finland
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89
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Shabbir Hussain M, Wheeldon I, Blenner MA. A Strong Hybrid Fatty Acid Inducible Transcriptional Sensor Built From Yarrowia lipolytica Upstream Activating and Regulatory Sequences. Biotechnol J 2017; 12. [PMID: 28731568 DOI: 10.1002/biot.201700248] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/21/2017] [Indexed: 01/24/2023]
Abstract
The engineering of Yarrowia lipolytica to accumulate lipids with high titers and productivities has been enabled with a handful of constitutive promoters for pathway engineering. However, the development of promoters that are both strong and lipid responsive could greatly benefit the bioproduction efficiency of lipid-derived oleochemicals in oleaginous yeast. In this study, a fatty acid regulated hybrid promoter for use in Y. lipolytica is engineered. A 200 bp upstream regulatory sequence in the peroxisomal acyl CoA oxidase 2 (POX2) promoter is identified. Further analysis of the promoter sequence reveal a regulatory sequence, that when used in tandem repeats, lead to a 48-fold induction of gene expression relative to glucose and fourfold higher than the native POX2 promoter. To date, this is the strongest inducible promoter reported in Y. lipolytica. Taken together, the results show that it is possible to engineer strong promoters that retain strong inducibility. These types of promoters will be useful in controlling metabolism and as fatty acid sensors.
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Affiliation(s)
| | - Ian Wheeldon
- Chemical & Environmental Engineering, University of California Riverside, Riverside, CA, USA
| | - Mark A Blenner
- Chemical & Biomolecular Engineering, Clemson University, Clemson, SC, USA
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90
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Comer AD, Long MR, Reed JL, Pfleger BF. Flux Balance Analysis Indicates that Methane Is the Lowest Cost Feedstock for Microbial Cell Factories. Metab Eng Commun 2017; 5:26-33. [PMID: 28989864 PMCID: PMC5628509 DOI: 10.1016/j.meteno.2017.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The low cost of natural gas has driven significant interest in using C1 carbon sources (e.g. methane, methanol, CO, syngas) as feedstocks for producing liquid transportation fuels and commodity chemicals. Given the large contribution of sugar and lignocellulosic feedstocks to biorefinery operating costs, natural gas and other C1 sources may provide an economic advantage. To assess the relative costs of these feedstocks, we performed flux balance analysis on genome-scale metabolic models to calculate the maximum theoretical yields of chemical products from methane, methanol, acetate, and glucose. Yield calculations were performed for every metabolite (as a proxy for desired products) in the genome-scale metabolic models of three organisms: Escherichia coli (bacterium), Saccharomyces cerevisiae (yeast), and Synechococcus sp. PCC 7002 (cyanobacterium). The calculated theoretical yields and current feedstock prices provided inputs to create comparative feedstock cost surfaces. Our analysis shows that, at current market prices, methane feedstock costs are consistently lower than glucose when used as a carbon and energy source for microbial chemical production. Conversely, methanol is costlier than glucose under almost all price scenarios. Acetate feedstock costs could be less than glucose given efficient acetate production from low-cost syngas using nascent biological gas to liquids (BIO-GTL) technologies. Our analysis suggests that research should focus on overcoming the technical challenges of methane assimilation and/or yield of acetate via BIO-GTL to take advantage of low-cost natural gas rather than using methanol as a feedstock. Review of C1 assimilation strategies is presented. Flux balance analysis used to create relative feedstock cost surfaces. Methane found to be the lowest cost feedstock for conversion of C1 compounds.
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Affiliation(s)
- Austin D Comer
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706
| | - Matthew R Long
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706
| | - Jennifer L Reed
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706.,Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706
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91
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Application of metabolic controls for the maximization of lipid production in semicontinuous fermentation. Proc Natl Acad Sci U S A 2017. [PMID: 28630295 DOI: 10.1073/pnas.1703321114] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acetic acid can be generated through syngas fermentation, lignocellulosic biomass degradation, and organic waste anaerobic digestion. Microbial conversion of acetate into triacylglycerols for biofuel production has many advantages, including low-cost or even negative-cost feedstock and environmental benefits. The main issue stems from the dilute nature of acetate produced in such systems, which is costly to be processed on an industrial scale. To tackle this problem, we established an efficient bioprocess for converting dilute acetate into lipids, using the oleaginous yeast Yarrowia lipolytica in a semicontinuous system. The implemented design used low-strength acetic acid in both salt and acid forms as carbon substrate and a cross-filtration module for cell recycling. Feed controls for acetic acid and nitrogen based on metabolic models and online measurement of the respiratory quotient were used. The optimized process was able to sustain high-density cell culture using acetic acid of only 3% and achieved a lipid titer, yield, and productivity of 115 g/L, 0.16 g/g, and 0.8 g⋅L-1⋅h-1, respectively. No carbon substrate was detected in the effluent stream, indicating complete utilization of acetate. These results represent a more than twofold increase in lipid production metrics compared with the current best-performing results using concentrated acetic acid as carbon feed.
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92
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Syngas Fermentation: A Microbial Conversion Process of Gaseous Substrates to Various Products. FERMENTATION-BASEL 2017. [DOI: 10.3390/fermentation3020028] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biomass and other carbonaceous materials can be gasified to produce syngas with high concentrations of CO and H2. Feedstock materials include wood, dedicated energy crops, grain wastes, manufacturing or municipal wastes, natural gas, petroleum and chemical wastes, lignin, coal and tires. Syngas fermentation converts CO and H2 to alcohols and organic acids and uses concepts applicable in fermentation of gas phase substrates. The growth of chemoautotrophic microbes produces a wide range of chemicals from the enzyme platform of native organisms. In this review paper, the Wood–Ljungdahl biochemical pathway used by chemoautotrophs is described including balanced reactions, reaction sites physically located within the cell and cell mechanisms for energy conservation that govern production. Important concepts discussed include gas solubility, mass transfer, thermodynamics of enzyme-catalyzed reactions, electrochemistry and cellular electron carriers and fermentation kinetics. Potential applications of these concepts include acid and alcohol production, hydrogen generation and conversion of methane to liquids or hydrogen.
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93
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LaBelle EV, May HD. Energy Efficiency and Productivity Enhancement of Microbial Electrosynthesis of Acetate. Front Microbiol 2017; 8:756. [PMID: 28515713 PMCID: PMC5413574 DOI: 10.3389/fmicb.2017.00756] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/12/2017] [Indexed: 12/02/2022] Open
Abstract
It was hypothesized that a lack of acetogenic biomass (biocatalyst) at the cathode of a microbial electrosynthesis system, due to electron and nutrient limitations, has prevented further improvement in acetate productivity and efficiency. In order to increase the biomass at the cathode and thereby performance, a bioelectrochemical system with this acetogenic community was operated under galvanostatic control and continuous media flow through a reticulated vitreous carbon (RVC) foam cathode. The combination of galvanostatic control and the high surface area cathode reduced the electron limitation and the continuous flow overcame the nutrient limitation while avoiding the accumulation of products and potential inhibitors. These conditions were set with the intention of operating the biocathode through the production of H2. Biofilm growth occurred on and within the unmodified RVC foam regardless of vigorous H2 generation on the cathode surface. A maximum volumetric rate or space time yield for acetate production of 0.78 g/Lcatholyte/h was achieved with 8 A/Lcatholyte (83.3 A/m2projected surface area of cathode) supplied to the continuous flow/culture bioelectrochemical reactors. The total Coulombic efficiency in H2 and acetate ranged from approximately 80-100%, with a maximum of 35% in acetate. The overall energy efficiency ranged from approximately 35-42% with a maximum to acetate of 12%.
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Affiliation(s)
| | - Harold D. May
- Hollings Marine Laboratory, Marine Biomedicine and Environmental Science Center, Department of Microbiology and Immunology, Medical University of South Carolina, CharlestonSC, USA
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94
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Emerson DF, Al Ghatta A, Woolston BM, Fay A, Kumar A, Stephanopoulos G. Theoretical analysis of natural gas recovery from marginal wells with a deep well reactor. AIChE J 2017. [DOI: 10.1002/aic.15738] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- David Frederic Emerson
- Dept. of Chemical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
| | - Amir Al Ghatta
- Dept. of Chemical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
| | - Benjamin M. Woolston
- Dept. of Chemical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
| | - Adrian Fay
- Dept. of Chemical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
| | - Amit Kumar
- Dept. of Chemical Engineering and Dept. of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
| | - Gregory Stephanopoulos
- Dept. of Chemical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridge MA02139
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95
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96
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Optimal synthesis of integrated process for co-production of biodiesel and hydrotreated vegetable oil (HVO) diesel from hybrid oil feedstocks. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/b978-0-444-63965-3.50114-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
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97
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98
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Richter H, Molitor B, Diender M, Sousa DZ, Angenent LT. A Narrow pH Range Supports Butanol, Hexanol, and Octanol Production from Syngas in a Continuous Co-culture of Clostridium ljungdahlii and Clostridium kluyveri with In-Line Product Extraction. Front Microbiol 2016; 7:1773. [PMID: 27877166 PMCID: PMC5099930 DOI: 10.3389/fmicb.2016.01773] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/21/2016] [Indexed: 12/19/2022] Open
Abstract
Carboxydotrophic bacteria (CTB) have received attention due to their ability to synthesize commodity chemicals from producer gas and synthesis gas (syngas). CTB have an important advantage of a high product selectivity compared to chemical catalysts. However, the product spectrum of wild-type CTB is narrow. Our objective was to investigate whether a strategy of combining two wild-type bacterial strains into a single, continuously fed bioprocessing step would be promising to broaden the product spectrum. Here, we have operated a syngas-fermentation process with Clostridium ljungdahlii and Clostridium kluyveri with in-line product extraction through gas stripping and product condensing within the syngas recirculation line. The main products from C. ljungdahlii fermentation at a pH of 6.0 were ethanol and acetate at net volumetric production rates of 65.5 and 431 mmol C·L−1·d−1, respectively. An estimated 2/3 of total ethanol produced was utilized by C. kluyveri to chain elongate with the reverse β-oxidation pathway, resulting in n-butyrate and n-caproate at net rates of 129 and 70 mmol C·L−1·d−1, respectively. C. ljungdahlii likely reduced the produced carboxylates to their corresponding alcohols with the reductive power from syngas. This resulted in the longer-chain alcohols n-butanol, n-hexanol, and n-octanol at net volumetric production rates of 39.2, 31.7, and 0.045 mmol C·L−1·d−1, respectively. The continuous production of the longer-chain alcohols occurred only within a narrow pH spectrum of 5.7–6.4 due to the pH discrepancy between the two strains. Regardless whether other wild-type strains could overcome this pH discrepancy, the specificity (mol carbon in product per mol carbon in all other liquid products) for each longer-chain alcohol may never be high in a single bioprocessing step. This, because two bioprocesses compete for intermediates (i.e., carboxylates): (1) chain elongation; and (2) biological reduction. This innate competition resulted in a mixture of n-butanol and n-hexanol with traces of n-octanol.
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Affiliation(s)
- Hanno Richter
- Department for Biological and Environmental Engineering, Cornell University Ithaca, NY, USA
| | - Bastian Molitor
- Department for Biological and Environmental Engineering, Cornell University Ithaca, NY, USA
| | - Martijn Diender
- Laboratory of Microbiology, Wageningen University Wageningen, Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University Wageningen, Netherlands
| | - Largus T Angenent
- Department for Biological and Environmental Engineering, Cornell UniversityIthaca, NY, USA; Atkinson Center for a Sustainable Future, Cornell UniversityIthaca, NY, USA
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99
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Gonzalez JE, Antoniewicz MR. Tracing metabolism from lignocellulosic biomass and gaseous substrates to products with stable-isotopes. Curr Opin Biotechnol 2016; 43:86-95. [PMID: 27780112 DOI: 10.1016/j.copbio.2016.10.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 12/12/2022]
Abstract
Engineered microbes offer a practical and sustainable alternative to traditional industrial approaches. To increase the economic feasibility of biological processes, microbial isolates are engineered to take up inexpensive feedstocks (including lignocellulosic biomass, syngas, methane, and carbon dioxide), and convert them into substrates of central metabolism and further into value-added products. To trace the metabolism of these feedstocks into products, isotopic tracers are applied together with isotopomer analysis techniques such as 13C-metabolic flux analysis to provide a detailed picture of pathway utilization. Flux data is then integrated with kinetic models and constraint-based approaches to identify metabolic bottlenecks, propose novel metabolic engineering strategies, and improve process performance.
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Affiliation(s)
- Jacqueline E Gonzalez
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA.
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100
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Desai SH, Koryakina I, Case AE, Toney MD, Atsumi S. Biological conversion of gaseous alkenes to liquid chemicals. Metab Eng 2016; 38:98-104. [PMID: 27424209 DOI: 10.1016/j.ymben.2016.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/11/2016] [Indexed: 10/21/2022]
Abstract
Industrial gas-to-liquid (GTL) technologies are well developed. They generally employ syngas, require complex infrastructure, and need high capital investment to be economically viable. Alternatively, biological conversion has the potential to be more efficient, and easily deployed to remote areas on relatively small scales for the utilization of otherwise stranded resources. The present study demonstrates a novel biological GTL process in which engineered Escherichia coli converts C2-C4 gaseous alkenes into liquid diols. Diols are versatile industrially important chemicals, used routinely as antifreeze agents, polymer precursors amongst many other applications. Heterologous co-expression of a monooxygenase and an epoxide hydrolase in E. coli allows whole cell conversion of C2-C4 alkenes for the formation of ethylene glycol, 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol at ambient temperature and pressure in one pot. Increasing intracellular NADH supply via addition of formate and a formate dehydrogenase increases ethylene glycol production titers, resulting in an improved productivity of 9mg/L/h and a final titer of 250mg/L. This represents a novel biological method for GTL conversion of alkenes to industrially valuable diols.
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Affiliation(s)
- Shuchi H Desai
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Irina Koryakina
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Anna E Case
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Michael D Toney
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
| | - Shota Atsumi
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
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