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Hirokawa Y, Matsuo S, Hamada H, Matsuda F, Hanai T. Metabolic engineering of Synechococcus elongatus PCC 7942 for improvement of 1,3-propanediol and glycerol production based on in silico simulation of metabolic flux distribution. Microb Cell Fact 2017; 16:212. [PMID: 29178875 PMCID: PMC5702090 DOI: 10.1186/s12934-017-0824-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/13/2017] [Indexed: 12/22/2022] Open
Abstract
Background Production directly from carbon dioxide by engineered cyanobacteria is one of the promising technologies for sustainable future. Previously, we have successfully achieved 1,3-propanediol (1,3-PDO) production using Synechococcus elongatus PCC 7942 with a synthetic metabolic pathway. The strain into which the synthetic metabolic pathway was introduced produced 3.48 mM (0.265 g/L) 1,3-PDO and 14.3 mM (1.32 g/L) glycerol during 20 days of incubation. In this study, the productivities of 1,3-PDO were improved by gene disruption selected by screening with in silico simulation. Methods First, a stoichiometric metabolic model was applied to prediction of cellular metabolic flux distribution in a 1,3-PDO-producing strain of S. elongatus PCC 7942. A genome-scale model of S. elongatus PCC 7942 constructed by Knoop was modified by the addition of a synthetic metabolic pathway for 1,3-PDO production. Next, the metabolic flux distribution predicted by metabolic flux balance analysis (FBA) was used for in silico simulation of gene disruption. As a result of gene disruption simulation, NADPH dehydrogenase 1 (NDH-1) complexes were found by screening to be the most promising candidates for disruption to improve 1,3-PDO production. The effect of disruption of the gene encoding a subunit of the NDH-1 complex was evaluated in the 1,3-PDO-producing strain. Results and Conclusions During 20 days of incubation, the ndhF1-null 1,3-PDO-producing strain showed the highest titers: 4.44 mM (0.338 g/L) 1,3-PDO and 30.3 mM (2.79 g/L) glycerol. In this study, we successfully improved 1,3-PDO productivity on the basis of in silico simulation of gene disruption. Electronic supplementary material The online version of this article (10.1186/s12934-017-0824-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yasutaka Hirokawa
- Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Shingo Matsuo
- Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Hiroyuki Hamada
- Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Fumio Matsuda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Taizo Hanai
- Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
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Knoot CJ, Ungerer J, Wangikar PP, Pakrasi HB. Cyanobacteria: Promising biocatalysts for sustainable chemical production. J Biol Chem 2017; 293:5044-5052. [PMID: 28972147 DOI: 10.1074/jbc.r117.815886] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cyanobacteria are photosynthetic prokaryotes showing great promise as biocatalysts for the direct conversion of CO2 into fuels, chemicals, and other value-added products. Introduction of just a few heterologous genes can endow cyanobacteria with the ability to transform specific central metabolites into many end products. Recent engineering efforts have centered around harnessing the potential of these microbial biofactories for sustainable production of chemicals conventionally produced from fossil fuels. Here, we present an overview of the unique chemistry that cyanobacteria have been co-opted to perform. We highlight key lessons learned from these engineering efforts and discuss advantages and disadvantages of various approaches.
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Affiliation(s)
- Cory J Knoot
- From the Department of Biology, Washington University, St. Louis, Missouri 63130 and
| | - Justin Ungerer
- From the Department of Biology, Washington University, St. Louis, Missouri 63130 and
| | - Pramod P Wangikar
- the Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Himadri B Pakrasi
- From the Department of Biology, Washington University, St. Louis, Missouri 63130 and
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A molecular rheostat maintains ATP levels to drive a synthetic biochemistry system. Nat Chem Biol 2017; 13:938-942. [PMID: 28671683 DOI: 10.1038/nchembio.2418] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/11/2017] [Indexed: 11/08/2022]
Abstract
Synthetic biochemistry seeks to engineer complex metabolic pathways for chemical conversions outside the constraints of the cell. Establishment of effective and flexible cell-free systems requires the development of simple systems to replace the intricate regulatory mechanisms that exist in cells for maintaining high-energy cofactor balance. Here we describe a simple rheostat that regulates ATP levels by controlling the flow down either an ATP-generating or non-ATP-generating pathway according to the free-phosphate concentration. We implemented this concept for the production of isobutanol from glucose. The rheostat maintains adequate ATP concentrations even in the presence of ATPase contamination. The final system including the rheostat produced 24.1 ± 1.8 g/L of isobutanol from glucose in 91% theoretical yield with an initial productivity of 1.3 g/L/h. The molecular rheostat concept can be used in the design of continuously operating, self-sustaining synthetic biochemistry systems.
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Hendry JI, Prasannan C, Ma F, Möllers KB, Jaiswal D, Digmurti M, Allen DK, Frigaard NU, Dasgupta S, Wangikar PP. Rerouting of carbon flux in a glycogen mutant of cyanobacteria assessed via isotopically non-stationary 13 C metabolic flux analysis. Biotechnol Bioeng 2017; 114:2298-2308. [PMID: 28600876 DOI: 10.1002/bit.26350] [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] [Received: 02/27/2017] [Revised: 06/09/2017] [Accepted: 06/09/2017] [Indexed: 01/14/2023]
Abstract
Cyanobacteria, which constitute a quantitatively dominant phylum, have attracted attention in biofuel applications due to favorable physiological characteristics, high photosynthetic efficiency and amenability to genetic manipulations. However, quantitative aspects of cyanobacterial metabolism have received limited attention. In the present study, we have performed isotopically non-stationary 13 C metabolic flux analysis (INST-13 C-MFA) to analyze rerouting of carbon in a glycogen synthase deficient mutant strain (glgA-I glgA-II) of the model cyanobacterium Synechococcus sp. PCC 7002. During balanced photoautotrophic growth, 10-20% of the fixed carbon is stored in the form of glycogen via a pathway that is conserved across the cyanobacterial phylum. Our results show that deletion of glycogen synthase gene orchestrates cascading effects on carbon distribution in various parts of the metabolic network. Carbon that was originally destined to be incorporated into glycogen gets partially diverted toward alternate storage molecules such as glucosylglycerol and sucrose. The rest is partitioned within the metabolic network, primarily via glycolysis and tricarboxylic acid cycle. A lowered flux toward carbohydrate synthesis and an altered distribution at the glucose-1-phosphate node indicate flexibility in the network. Further, reversibility of glycogen biosynthesis reactions points toward the presence of futile cycles. Similar redistribution of carbon was also predicted by Flux Balance Analysis. The results are significant to metabolic engineering efforts with cyanobacteria where fixed carbon needs to be re-routed to products of interest. Biotechnol. Bioeng. 2017;114: 2298-2308. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- John I Hendry
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Charulata Prasannan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,DBT-Pan IIT Center for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Fangfang Ma
- Donald Danforth Plant Science Center, US Department of Agriculture, St. Louis, Missouri, 63132
| | - K Benedikt Möllers
- Department of Biology, University of Copenhagen, Helsingør, 3000, Denmark
| | - Damini Jaiswal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Madhuri Digmurti
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Doug K Allen
- Donald Danforth Plant Science Center, US Department of Agriculture, St. Louis, Missouri, 63132.,Agricultural Research Service, US Department of Agriculture, St. Louis, Missouri, 63132
| | | | - Santanu Dasgupta
- Reliance Research and Development Centre, Reliance Corporate Park, Reliance Industries Ltd., Thane-Belapur Road, Ghansoli, Navi Mumbai, 400 701, India
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,DBT-Pan IIT Center for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Arai S, Hayashihara K, Kanamoto Y, Shimizu K, Hirokawa Y, Hanai T, Murakami A, Honda H. Alcohol‐tolerant mutants of cyanobacterium
Synechococcus elongatus
PCC 7942 obtained by single‐cell mutant screening system. Biotechnol Bioeng 2017; 114:1771-1778. [DOI: 10.1002/bit.26307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/02/2017] [Accepted: 04/04/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Sayuri Arai
- Department of BiotechnologyGraduate School of EngineeringNagoya UniversityFuro‐choChikusa‐kuNagoyaAichi464‐8603Japan
| | | | - Yuki Kanamoto
- Kobe University Research Center for Inland SeasAwajiHyogoJapan
| | - Kazunori Shimizu
- Department of BiotechnologyGraduate School of EngineeringNagoya UniversityFuro‐choChikusa‐kuNagoyaAichi464‐8603Japan
| | - Yasutaka Hirokawa
- Laboratory for BioinformaticsGraduate School of Systems Life SciencesKyushu UniversityHigashi‐kuFukuokaJapan
| | - Taizo Hanai
- Laboratory for BioinformaticsGraduate School of Systems Life SciencesKyushu UniversityHigashi‐kuFukuokaJapan
| | - Akio Murakami
- Kobe University Research Center for Inland SeasAwajiHyogoJapan
| | - Hiroyuki Honda
- Department of BiotechnologyGraduate School of EngineeringNagoya UniversityFuro‐choChikusa‐kuNagoyaAichi464‐8603Japan
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Construction of a novel d-lactate producing pathway from dihydroxyacetone phosphate of the Calvin cycle in cyanobacterium, Synechococcus elongatus PCC 7942. J Biosci Bioeng 2017; 124:54-61. [PMID: 28325659 DOI: 10.1016/j.jbiosc.2017.02.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 02/23/2017] [Accepted: 02/23/2017] [Indexed: 01/10/2023]
Abstract
Using engineered cyanobacteria to produce various chemicals from carbon dioxide is a promising technology for a sustainable future. Lactate is a valuable commodity that can be used for the biodegradable plastic, polylactic acid. Typically, lactate production using engineered cyanobacteria was via the conversion of pyruvate in glycolysis by lactate dehydrogenase. In cyanobacteria, the metabolic flux in the Calvin cycle is higher than that in glycolysis under photoautotrophic conditions. The construction of a novel lactate producing pathway that uses metabolites from the Calvin cycle could potentially increase lactate productivity in cyanobacteria. In order to develop such a novel lactate production pathway, we engineered a cyanobacterium Synechococcus elongatus PCC 7942 strain that produced lactate directly from carbon dioxide using dihydroxyacetone phosphate (DHAP) via methylglyoxal. We confirmed that wild-type strain of S. elongatus PCC 7942 could produce lactate using exogenous methylglyoxal. A methylglyoxal synthase gene, mgsA, from Escherichia coli was introduced into Synechococcus elongates PCC 7942 for conversion of DHAP to methylglyoxal. This engineered strain produced lactate directly from carbon dioxide. Genes encoding intrinsic putative glyoxalase I, II (Synpcc7942_0638, 1403) and the lactate/H+ symporter from E. coli (lldP) were additionally introduced to enhance the production. For higher lactate production, it was important to maintain elevated extracellular pH due to the characteristics of lactate exporting system. In this study, the highest lactate titer of 13.7 mM (1.23 g/l) was achieved during a 24-day incubation with the engineered S. elongatus PCC 7942 strain possessing the novel lactate producing pathway.
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Improvement of 1,3-propanediol production using an engineered cyanobacterium, Synechococcus elongatus by optimization of the gene expression level of a synthetic metabolic pathway and production conditions. Metab Eng 2017; 39:192-199. [DOI: 10.1016/j.ymben.2016.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/08/2016] [Accepted: 12/05/2016] [Indexed: 11/17/2022]
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Abramson BW, Kachel B, Kramer DM, Ducat DC. Increased Photochemical Efficiency in Cyanobacteria via an Engineered Sucrose Sink. PLANT & CELL PHYSIOLOGY 2016; 57:2451-2460. [PMID: 27742883 DOI: 10.1093/pcp/pcw169] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/25/2016] [Indexed: 06/06/2023]
Abstract
In plants, a limited capacity to utilize or export the end-products of the Calvin-Benson cycle (CB) from photosynthetically active source cells to non-photosynthetic sink cells can result in reduced carbon capture and photosynthetic electron transport (PET), and lowered photochemical efficiency. The down-regulation of photosynthesis caused by reduced capacity to utilize photosynthate has been termed 'sink limitation'. Recently, several cyanobacterial and algal strains engineered to overproduce target metabolites have exhibited increased photochemistry, suggesting that possible source-sink regulatory mechanisms may be involved. We directly examined photochemical properties following induction of a heterologous sucrose 'sink' in the unicellular cyanobacterium Synechococcus elongatus PCC 7942. We show that total photochemistry increases proportionally to the experimentally controlled rate of sucrose export. Importantly, the quantum yield of PSII (ΦII) increases in response to sucrose export while the PET chain becomes more oxidized from less PSI acceptor-side limitation, suggesting increased CB activity and a decrease in sink limitation. Enhanced photosynthetic activity and linear electron flow are detectable within hours of induction of the heterologous sink and are independent of pigmentation alterations or the ionic/osmotic effects of the induction system. These observations provide direct evidence that secretion of heterologous carbon bioproducts can be used as an alternative approach to improve photosynthetic efficiency, presumably by by-passing sink limitation. Our results also suggest that engineered microalgal production strains are valuable alternative models for examining photosynthetic sink limitation because they enable greater control and monitoring of metabolite fluxes relative to plants.
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Affiliation(s)
- Bradley W Abramson
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Cell and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Benjamin Kachel
- Department of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - David M Kramer
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Daniel C Ducat
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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59
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Cyanobacterial metabolic engineering for biofuel and chemical production. Curr Opin Chem Biol 2016; 35:43-50. [DOI: 10.1016/j.cbpa.2016.08.023] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 11/21/2022]
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Loder AJ, Zeldes BM, Conway JM, Counts JA, Straub CT, Khatibi PA, Lee LL, Vitko NP, Keller MW, Rhaesa AM, Rubinstein GM, Scott IM, Lipscomb GL, Adams MW, Kelly RM. Extreme Thermophiles as Metabolic Engineering Platforms: Strategies and Current Perspective. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Andrew J. Loder
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Benjamin M. Zeldes
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Jonathan M. Conway
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - James A. Counts
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Christopher T. Straub
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Piyum A. Khatibi
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Laura L. Lee
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Nicholas P. Vitko
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
| | - Matthew W. Keller
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Amanda M. Rhaesa
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Gabe M. Rubinstein
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Israel M. Scott
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Gina L. Lipscomb
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Michael W.W. Adams
- University of Georgia; Department of Biochemistry and Molecular Biology; Life Sciences Bldg., University of Georgia, Athens GA 30602-7229, USA
| | - Robert M. Kelly
- North Carolina State University; Department of Chemical and Biomolecular Engineering; EB-1, 911 Partners Way Raleigh NC 27695-7905 USA
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Namakoshi K, Nakajima T, Yoshikawa K, Toya Y, Shimizu H. Combinatorial deletions of glgC and phaCE enhance ethanol production in Synechocystis sp. PCC 6803. J Biotechnol 2016; 239:13-19. [PMID: 27693092 DOI: 10.1016/j.jbiotec.2016.09.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/23/2016] [Accepted: 09/26/2016] [Indexed: 11/28/2022]
Abstract
Synechocystis sp. PCC 6803 is an attractive host for bio-ethanol production. In the present study, a nitrogen starvation approach was applied on an ethanol producing strain for inhibiting the growth, since ethanol production competes with the cell growth. The effect of gene deletions in the glycogen and polyhydroxybutyrate (PHB) synthesis pathways was investigated. Measurements of intracellular glycogen and PHB revealed that the glycogen was accumulated under the nitrogen starvation condition and the gene deletion of glycogen synthesis pathway caused the accumulation of PHB. The ethanol producing strain harboring deletions for both the glycogen and the PHB synthesis pathways (ΔglgCΔphaCE/EtOH) produced ethanol at the specific rate of 240mgg (dry cell weight)-1 day-1 under the nitrogen starvation condition. In a high cell density culture (OD730=50) using this ΔglgCΔphaCE/EtOH strain, the ethanol production rates were 1.08 and 2.01gL-1 day-1 under light conditions of 40 and 80μmolm-2s-1, respectively.
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Affiliation(s)
- Katsunori Namakoshi
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tubasa Nakajima
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Katsunori Yoshikawa
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Case AE, Atsumi S. Cyanobacterial chemical production. J Biotechnol 2016; 231:106-114. [DOI: 10.1016/j.jbiotec.2016.05.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 05/19/2016] [Indexed: 01/03/2023]
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Cyanobacterial chassis engineering for enhancing production of biofuels and chemicals. Appl Microbiol Biotechnol 2016; 100:3401-13. [DOI: 10.1007/s00253-016-7374-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 01/29/2016] [Accepted: 02/01/2016] [Indexed: 10/22/2022]
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He L, Wu SG, Wan N, Reding AC, Tang YJ. Simulating cyanobacterial phenotypes by integrating flux balance analysis, kinetics, and a light distribution function. Microb Cell Fact 2015; 14:206. [PMID: 26705097 PMCID: PMC5574461 DOI: 10.1186/s12934-015-0396-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genome-scale models (GSMs) are widely used to predict cyanobacterial phenotypes in photobioreactors (PBRs). However, stoichiometric GSMs mainly focus on fluxome that result in maximal yields. Cyanobacterial metabolism is controlled by both intracellular enzymes and photobioreactor conditions. To connect both intracellular and extracellular information and achieve a better understanding of PBRs productivities, this study integrates a genome-scale metabolic model of Synechocystis 6803 with growth kinetics, cell movements, and a light distribution function. The hybrid platform not only maps flux dynamics in cells of sub-populations but also predicts overall production titer and rate in PBRs. RESULTS Analysis of the integrated GSM demonstrates several results. First, cyanobacteria are capable of reaching high biomass concentration (>20 g/L in 21 days) in PBRs without light and CO2 mass transfer limitations. Second, fluxome in a single cyanobacterium may show stochastic changes due to random cell movements in PBRs. Third, insufficient light due to cell self-shading can activate the oxidative pentose phosphate pathway in subpopulation cells. Fourth, the model indicates that the removal of glycogen synthesis pathway may not improve cyanobacterial bio-production in large-size PBRs, because glycogen can support cell growth in the dark zones. Based on experimental data, the integrated GSM estimates that Synechocystis 6803 in shake flask conditions has a photosynthesis efficiency of ~2.7 %. CONCLUSIONS The multiple-scale integrated GSM, which examines both intracellular and extracellular domains, can be used to predict production yield/rate/titer in large-size PBRs. More importantly, genetic engineering strategies predicted by a traditional GSM may work well only in optimal growth conditions. In contrast, the integrated GSM may reveal mutant physiologies in diverse bioreactor conditions, leading to the design of robust strains with high chances of success in industrial settings.
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Affiliation(s)
- Lian He
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
| | - Stephen G Wu
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
| | - Ni Wan
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, 63130, USA.
| | - Adrienne C Reding
- Department of Biochemistry and Molecular Biology, College of Wooster, Wooster, OH, 44691, USA.
| | - Yinjie J Tang
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
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Metabolic engineering of cyanobacteria for photosynthetic 3-hydroxypropionic acid production from CO2 using Synechococcus elongatus PCC 7942. Metab Eng 2015; 31:163-70. [DOI: 10.1016/j.ymben.2015.08.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 04/16/2015] [Accepted: 08/05/2015] [Indexed: 02/04/2023]
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67
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Cyanobacterial photo-driven mixotrophic metabolism and its advantages for biosynthesis. Front Chem Sci Eng 2015. [DOI: 10.1007/s11705-015-1521-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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68
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Dynamics of Photosynthesis in a Glycogen-Deficient glgC Mutant of Synechococcus sp. Strain PCC 7002. Appl Environ Microbiol 2015; 81:6210-22. [PMID: 26150450 DOI: 10.1128/aem.01751-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 06/25/2015] [Indexed: 11/20/2022] Open
Abstract
Cyanobacterial glycogen-deficient mutants display impaired degradation of light-harvesting phycobilisomes under nitrogen-limiting growth conditions and secrete a suite of organic acids as a putative reductant-spilling mechanism. This genetic background, therefore, represents an important platform to better understand the complex relationships between light harvesting, photosynthetic electron transport, carbon fixation, and carbon/nitrogen metabolisms. In this study, we conducted a comprehensive analysis of the dynamics of photosynthesis as a function of reductant sink manipulation in a glycogen-deficient glgC mutant of Synechococcus sp. strain PCC 7002. The glgC mutant showed increased susceptibility to photoinhibition during the initial phase of nitrogen deprivation. However, after extended periods of nitrogen deprivation, glgC mutant cells maintained higher levels of photosynthetic activity than the wild type, supporting continuous organic acid secretion in the absence of biomass accumulation. In contrast to the wild type, the glgC mutant maintained efficient energy transfer from phycobilisomes to photosystem II (PSII) reaction centers, had an elevated PSII/PSI ratio as a result of reduced PSII degradation, and retained a nitrogen-replete-type ultrastructure, including an extensive thylakoid membrane network, after prolonged nitrogen deprivation. Together, these results suggest that multiple global signals for nitrogen deprivation are not activated in the glgC mutant, allowing the maintenance of active photosynthetic complexes under conditions where photosynthesis would normally be abolished.
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Savakis P, Hellingwerf KJ. Engineering cyanobacteria for direct biofuel production from CO2. Curr Opin Biotechnol 2015; 33:8-14. [DOI: 10.1016/j.copbio.2014.09.007] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 02/02/2023]
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70
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Angermayr SA, Gorchs Rovira A, Hellingwerf KJ. Metabolic engineering of cyanobacteria for the synthesis of commodity products. Trends Biotechnol 2015; 33:352-61. [DOI: 10.1016/j.tibtech.2015.03.009] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/24/2015] [Accepted: 03/25/2015] [Indexed: 11/24/2022]
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Dexter J, Armshaw P, Sheahan C, Pembroke JT. The state of autotrophic ethanol production in Cyanobacteria. J Appl Microbiol 2015; 119:11-24. [PMID: 25865951 DOI: 10.1111/jam.12821] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 02/23/2015] [Accepted: 04/07/2015] [Indexed: 12/20/2022]
Abstract
Ethanol production directly from CO2 , utilizing genetically engineered photosynthetic cyanobacteria as a biocatalyst, offers significant potential as a renewable and sustainable source of biofuel. Despite the current absence of a commercially successful production system, significant resources have been deployed to realize this goal. Utilizing the pyruvate decarboxylase from Zymomonas species, metabolically derived pyruvate can be converted to ethanol. This review of both peer-reviewed and patent literature focuses on the genetic modifications utilized for metabolic engineering and the resultant effect on ethanol yield. Gene dosage, induced expression and cassette optimizat-ion have been analyzed to optimize production, with production rates of 0·1-0·5 g L(-1) day(-1) being achieved. The current 'toolbox' of molecular manipulations and future directions focusing on applicability, addressing the primary challenges facing commercialization of cyanobacterial technologies are discussed.
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Affiliation(s)
- J Dexter
- Molecular and Structural Biochemistry Laboratory, Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland.,Department of Design and Manufacturing Engineering, University of Limerick, Limerick, Ireland.,Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | - P Armshaw
- Molecular and Structural Biochemistry Laboratory, Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland.,Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | - C Sheahan
- Department of Design and Manufacturing Engineering, University of Limerick, Limerick, Ireland
| | - J T Pembroke
- Molecular and Structural Biochemistry Laboratory, Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland.,Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
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72
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Xue Y, He Q. Cyanobacteria as cell factories to produce plant secondary metabolites. Front Bioeng Biotechnol 2015; 3:57. [PMID: 25973419 PMCID: PMC4412135 DOI: 10.3389/fbioe.2015.00057] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 04/14/2015] [Indexed: 01/23/2023] Open
Abstract
Cyanobacteria represent a promising platform for the production of plant secondary metabolites. Their capacity to express plant P450 proteins, which have essential functions in the biosynthesis of many plant secondary metabolites, makes cyanobacteria ideal for this purpose, and their photosynthetic capability allows cyanobacteria to grow with simple nutrient inputs. This review summarizes the advantages of using cyanobacteria to transgenically produce plant secondary metabolites. Some techniques to improve heterologous gene expression in cyanobacteria are discussed.
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Affiliation(s)
- Yong Xue
- Department of Applied Science, University of Arkansas at Little Rock , Little Rock, AR , USA
| | - Qingfang He
- Department of Applied Science, University of Arkansas at Little Rock , Little Rock, AR , USA
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73
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Carrieri D, Broadbent C, Carruth D, Paddock T, Ungerer J, Maness PC, Ghirardi M, Yu J. Enhancing photo-catalytic production of organic acids in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC, a strain incapable of glycogen storage. Microb Biotechnol 2015; 8:275-80. [PMID: 25616027 PMCID: PMC4353341 DOI: 10.1111/1751-7915.12243] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 09/26/2014] [Accepted: 10/25/2014] [Indexed: 11/28/2022] Open
Abstract
A key objective in microbial biofuels strain development is to maximize carbon flux to target products while minimizing cell biomass accumulation, such that ideally the algae and bacteria would operate in a photo-catalytic state. A brief period of such a physiological state has recently been demonstrated in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC strain incapable of glycogen storage. When deprived of nitrogen, the ΔglgC excretes the organic acids alpha-ketoglutarate and pyruvate for a number of days without increasing cell biomass. This study examines the relationship between the growth state and the photo-catalytic state, and characterizes the metabolic adaptability of the photo-catalytic state to increasing light intensity. It is found that the culture can transition naturally from the growth state into the photo-catalytic state when provided with limited nitrogen supply during the growth phase. Photosynthetic capacity and pigments are lost over time in the photo-catalytic state. Reversal to growth state is observed with re-addition of nitrogen nutrient, accompanied by restoration of photosynthetic capacity and pigment levels in the cells. While the overall productivity increased under high light conditions, the ratio of alpha-ketoglutarate/pyruvate is altered, suggesting that carbon partition between the two products is adaptable to environmental conditions.
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Affiliation(s)
- Damian Carrieri
- Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA
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74
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Montgomery BL. The Regulation of Light Sensing and Light-Harvesting Impacts the Use of Cyanobacteria as Biotechnology Platforms. Front Bioeng Biotechnol 2014; 2:22. [PMID: 25023122 PMCID: PMC4090899 DOI: 10.3389/fbioe.2014.00022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/13/2014] [Indexed: 12/22/2022] Open
Abstract
Light is harvested in cyanobacteria by chlorophyll-containing photosystems embedded in the thylakoid membranes and phycobilisomes (PBSs), photosystem-associated light-harvesting antennae. Light absorbed by the PBSs and photosystems can be converted to chemical energy through photosynthesis. Photosynthetically fixed carbon pools, which are constrained by photosynthetic light capture versus the dissipation of excess light absorbed, determine the available organismal energy budget. The molecular bases of the environmental regulation of photosynthesis, photoprotection, and photomorphogenesis are still being elucidated in cyanobacteria. Thus, the potential impacts of these phenomena on the efficacy of developing cyanobacteria as robust biotechnological platforms require additional attention. Current advances and persisting needs for developing cyanobacterial production platforms that are related to light sensing and harvesting include the development of tools to balance the utilization of absorbed photons for conversion to chemical energy and biomass versus light dissipation in photoprotective mechanisms. Such tools can be used to direct energy to more effectively support the production of desired bioproducts from sunlight.
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Affiliation(s)
- Beronda L. Montgomery
- Plant Research Laboratory, Department of Energy, Michigan State University, East Lansing, MI, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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75
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Davies FK, Work VH, Beliaev AS, Posewitz MC. Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002. Front Bioeng Biotechnol 2014; 2:21. [PMID: 25152894 PMCID: PMC4126464 DOI: 10.3389/fbioe.2014.00021] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/04/2014] [Indexed: 02/05/2023] Open
Abstract
The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L−1 limonene and 0.6 mg L−1 α-bisabolene through heterologous expression of the Mentha spicatal-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.
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Affiliation(s)
- Fiona K Davies
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, CO , USA
| | - Victoria H Work
- Civil and Environmental Engineering Division, Colorado School of Mines , Golden, CO , USA
| | - Alexander S Beliaev
- Biological Sciences Division, Pacific Northwest National Laboratory , Richland, WA , USA
| | - Matthew C Posewitz
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, CO , USA
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