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Tiwari D, Kumar N, Bongirwar R, Shukla P. Nutraceutical prospects of genetically engineered cyanobacteria- technological updates and significance. World J Microbiol Biotechnol 2024; 40:263. [PMID: 38980547 DOI: 10.1007/s11274-024-04064-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 06/23/2024] [Indexed: 07/10/2024]
Abstract
Genetically engineered cyanobacterial strains that have improved growth rate, biomass productivity, and metabolite productivity could be a better option for sustainable bio-metabolite production. The global demand for biobased metabolites with nutraceuticals and health benefits has increased due to their safety and plausible therapeutic and nutritional utility. Cyanobacteria are solar-powered green cellular factories that can be genetically tuned to produce metabolites with nutraceutical and pharmaceutical benefits. The present review discusses biotechnological endeavors for producing bioprospective compounds from genetically engineered cyanobacteria and discusses the challenges and troubleshooting faced during metabolite production. This review explores the cyanobacterial versatility, the use of engineered strains, and the techno-economic challenges associated with scaling up metabolite production from cyanobacteria. Challenges to produce cyanobacterial bioactive compounds with remarkable nutraceutical values have been discussed. Additionally, this review also summarises the challenges and future prospects of metabolite production from genetically engineered cyanobacteria as a sustainable approach.
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Affiliation(s)
- Deepali Tiwari
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
| | - Niwas Kumar
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
| | - Riya Bongirwar
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India.
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Karikomi M, Katayama N, Osanai T. Pyruvate kinase 2 from Synechocystis sp. PCC 6803 increased substrate affinity via glucose-6-phosphate and ribose-5-phosphate for phosphoenolpyruvate consumption. PLANT MOLECULAR BIOLOGY 2024; 114:60. [PMID: 38758412 PMCID: PMC11101554 DOI: 10.1007/s11103-023-01401-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 11/30/2023] [Indexed: 05/18/2024]
Abstract
Pyruvate kinase (Pyk, EC 2.7.1.40) is a glycolytic enzyme that generates pyruvate and adenosine triphosphate (ATP) from phosphoenolpyruvate (PEP) and adenosine diphosphate (ADP), respectively. Pyk couples pyruvate and tricarboxylic acid metabolisms. Synechocystis sp. PCC 6803 possesses two pyk genes (encoded pyk1, sll0587 and pyk2, sll1275). A previous study suggested that pyk2 and not pyk1 is essential for cell viability; however, its biochemical analysis is yet to be performed. Herein, we biochemically analyzed Synechocystis Pyk2 (hereafter, SyPyk2). The optimum pH and temperature of SyPyk2 were 7.0 and 55 °C, respectively, and the Km values for PEP and ADP under optimal conditions were 1.5 and 0.053 mM, respectively. SyPyk2 is activated in the presence of glucose-6-phosphate (G6P) and ribose-5-phosphate (R5P); however, it remains unaltered in the presence of adenosine monophosphate (AMP) or fructose-1,6-bisphosphate. These results indicate that SyPyk2 is classified as PykA type rather than PykF, stimulated by sugar monophosphates, such as G6P and R5P, but not by AMP. SyPyk2, considering substrate affinity and effectors, can play pivotal roles in sugar catabolism under nonphotosynthetic conditions.
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Affiliation(s)
- Masahiro Karikomi
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-Ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Noriaki Katayama
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-Ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-Ku, Kawasaki, Kanagawa, 214-8571, Japan.
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Ito S, Watanabe A, Osanai T. Regulation of L-aspartate oxidase contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803. PLANT PHYSIOLOGY 2024; 194:945-957. [PMID: 37936332 DOI: 10.1093/plphys/kiad580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/11/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023]
Abstract
Cyanobacteria have been promoted as a biomass resource that can contribute to carbon neutrality. Synechocystis sp. PCC 6803 is a model cyanobacterium that is widely used in various studies. NADP+ and NAD+ are electron receptors involved in energy metabolism. The NADP+/NAD+ ratio in Synechocystis sp. PCC 6803 is markedly higher than that in the heterotrophic bacterium Escherichia coli. In Synechocystis sp. PCC 6803, NADP+ primarily functions as an electron receptor during the light reaction of photosynthesis, and NADP+ biosynthesis is essential for photoautotrophic growth. Generally, the regulatory enzyme of NADP+ biosynthesis is NAD kinase, which catalyzes the phosphorylation of NAD+. However, a previous study suggested that the regulation of another enzyme contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803 under photoautotrophic conditions. L-Aspartate oxidase is the first enzyme in NAD(P)+ biosynthesis. In this study, we biochemically characterized Synechocystis sp. PCC 6803 L-aspartate oxidase and determined the phenotype of a Synechocystis sp. PCC 6803 mutant overexpressing L-aspartate oxidase. The catalytic efficiency of L-aspartate oxidase from Synechocystis sp. PCC 6803 was lower than that of L-aspartate oxidases and NAD kinases from other organisms. L-Aspartate oxidase activity was affected by different metabolites such as NADP+ and ATP. The L-aspartate oxidase-overexpressing strain grew faster than the wild-type strain under photoautotrophic conditions. The L-aspartate oxidase-overexpressing strain accumulated NADP+ under photoautotrophic conditions. These results indicate that the regulation of L-aspartate oxidase contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803 under photoautotrophic conditions. These findings provide insight into the regulatory mechanism of cyanobacterial NADP+ biosynthesis.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Atsuko Watanabe
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
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Akiyama M, Osanai T. Regulation of organic acid and hydrogen production by NADH/NAD + ratio in Synechocystis sp. PCC 6803. Front Microbiol 2024; 14:1332449. [PMID: 38249449 PMCID: PMC10797119 DOI: 10.3389/fmicb.2023.1332449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 12/12/2023] [Indexed: 01/23/2024] Open
Abstract
Cyanobacteria serve as useful hosts in the production of substances to support a low-carbon society. Specifically, the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803) can produce organic acids, such as acetate, lactate, and succinate, as well as hydrogen, under dark, anaerobic conditions. The efficient production of these compounds appears to be closely linked to the regulation of intracellular redox balance. Notably, alterations in intracellular redox balance have been believed to influence the production of organic acids and hydrogen. To achieve these alterations, genetic manipulations involved overexpressing malate dehydrogenase (MDH), knocking out d-lactate dehydrogenase (DDH), or knocking out acetate kinase (AK), which subsequently modified the quantities and ratios of organic acids and hydrogen under dark, anaerobic conditions. Furthermore, the mutants generated displayed changes in the oxidation of reducing powers and the nicotinamide adenine dinucleotide hydrogen (NADH)/NAD+ ratio when compared to the parental wild-type strain. These findings strongly suggest that intracellular redox balance, especially the NADH/NAD+ ratio, plays a pivotal role in the production of organic acids and hydrogen in Synechocystis 6803.
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Affiliation(s)
| | - Takashi Osanai
- School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
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Wang C, Pan G, Lu X, Qi W. Phosphorus solubilizing microorganisms: potential promoters of agricultural and environmental engineering. Front Bioeng Biotechnol 2023; 11:1181078. [PMID: 37251561 PMCID: PMC10213388 DOI: 10.3389/fbioe.2023.1181078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Phosphate solubilizing microorganisms (PSMs) are known as bacteria or fungi that make insoluble phosphorus in soil available to plants. To date, as beneficial microbes, studies on PSMs indicated they have potential applications in agriculture, environmental engineering, bioremediation, and biotechnology. Currently high cost and competition from local microbe are the most important factors hindering PSMs commercialization and application as for instance biofertilizer, soil conditioner or remediation agent, etc. There are several technical strategies can be engaged to approach the solutions of these issues, for instance mass production, advance soil preparation, genetic engineering, etc. On the other hand, further studies are needed to improve the efficiency and effectiveness of PSMs in solubilizing phosphates, promoting plant growth, soil remediation preferably. Hopefully, PSMs are going to be developed into ecofriendly tools for sustainable agriculture, environment protection and management in the future.
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Affiliation(s)
- Chengdong Wang
- Key Laboratory of Tobacco Biology and Processing, Ministry of Agriculture, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Guojun Pan
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Xin Lu
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, China
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Weicong Qi
- Excellence and Innovation Center, Jiangsu Academy of Agricultural Sciences, Nanjing, China
- Key Laboratory of Saline-Alkali Soil Improvement and Utilization (Coastal Saline-Alkali Lands), Ministry of Agriculture and Rural Affairs, Nanjing, China
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Yamane M, Osanai T. Nondiazotrophic cyanobacteria metabolic engineering for succinate and lactate production. ALGAL RES 2023. [DOI: 10.1016/j.algal.2023.103088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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Rodrigues JS, Bourgade B, Galle KR, Lindberg P. Mapping competitive pathways to terpenoid biosynthesis in Synechocystis sp. PCC 6803 using an antisense RNA synthetic tool. Microb Cell Fact 2023; 22:35. [PMID: 36823631 PMCID: PMC9951418 DOI: 10.1186/s12934-023-02040-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/10/2023] [Indexed: 02/25/2023] Open
Abstract
BACKGROUND Synechocystis sp. PCC 6803 utilizes pyruvate and glyceraldehyde 3-phosphate via the methylerythritol 4-phosphate (MEP) pathway for the biosynthesis of terpenoids. Considering the deep connection of the MEP pathway to the central carbon metabolism, and the low carbon partitioning towards terpenoid biosynthesis, significant changes in the metabolic network are required to increase cyanobacterial production of terpenoids. RESULTS We used the Hfq-MicC antisense RNA regulatory tool, under control of the nickel-inducible PnrsB promoter, to target 12 different genes involved in terpenoid biosynthesis, central carbon metabolism, amino acid biosynthesis and ATP production, and evaluated the changes in the performance of an isoprene-producing cyanobacterial strain. Six candidate targets showed a positive effect on isoprene production: three genes involved in terpenoid biosynthesis (crtE, chlP and thiG), two involved in amino acid biosynthesis (ilvG and ccmA) and one involved in sugar catabolism (gpi). The same strategy was applied to interfere with different parts of the terpenoid biosynthetic pathway in a bisabolene-producing strain. Increased bisabolene production was observed not only when interfering with chlorophyll a biosynthesis, but also with carotenogenesis. CONCLUSIONS We demonstrated that the Hfq-MicC synthetic tool can be used to evaluate the effects of gene knockdown on heterologous terpenoid production, despite the need for further optimization of the technique. Possible targets for future engineering of Synechocystis aiming at improved terpenoid microbial production were identified.
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Affiliation(s)
- João S. Rodrigues
- grid.8993.b0000 0004 1936 9457Department of Chemistry – Ångström, Uppsala University, Uppsala, Sweden
| | - Barbara Bourgade
- grid.8993.b0000 0004 1936 9457Department of Chemistry – Ångström, Uppsala University, Uppsala, Sweden
| | - Karen R. Galle
- grid.8993.b0000 0004 1936 9457Department of Chemistry – Ångström, Uppsala University, Uppsala, Sweden ,grid.5808.50000 0001 1503 7226Faculty of Sciences, University of Porto, Porto, Portugal
| | - Pia Lindberg
- Department of Chemistry - Ångström, Uppsala University, Uppsala, Sweden.
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Malic Enzyme, not Malate Dehydrogenase, Mainly Oxidizes Malate That Originates from the Tricarboxylic Acid Cycle in Cyanobacteria. mBio 2022; 13:e0218722. [PMID: 36314837 PMCID: PMC9765476 DOI: 10.1128/mbio.02187-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023] Open
Abstract
Oxygenic photoautotrophic bacteria, cyanobacteria, have the tricarboxylic acid (TCA) cycle, and metabolite production using the cyanobacterial TCA cycle has been spotlighted recently. The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 (Synechocystis 6803) has been used in various studies on the cyanobacterial TCA cycle. Malate oxidation in the TCA cycle is generally catalyzed by malate dehydrogenase (MDH). However, Synechocystis 6803 MDH (SyMDH) is less active than MDHs from other organisms. Additionally, SyMDH uses only NAD+ as a coenzyme, unlike other TCA cycle enzymes from Synechocystis 6803 that use NADP+. These results suggest that MDH rarely catalyzes malate oxidation in the cyanobacterial TCA cycle. Another enzyme catalyzing malate oxidation is malic enzyme (ME). We clarified which enzyme oxidizes malate that originates from the cyanobacterial TCA cycle using analyses focusing on ME and MDH. In contrast to SyMDH, Synechocystis 6803 ME (SyME) showed high activity when NADP+ was used as a coenzyme. Unlike the Synechocystis 6803 mutant lacking SyMDH, the mutant lacking SyME accumulated malate in the cells. ME was more highly preserved in the cyanobacterial genomes than MDH. These results indicate that ME mainly oxidizes malate that originates from the cyanobacterial TCA cycle (named the ME-dependent TCA cycle). The ME-dependent TCA cycle generates NADPH, not NADH. This is consistent with previous reports that NADPH is an electron carrier in the cyanobacterial respiratory chain. Our finding suggests the diversity of enzymes involved in the TCA cycle in the organisms, and analyses such as those performed in this study are necessary to determine the enzymes. IMPORTANCE Oxygenic photoautotrophic bacteria, namely, cyanobacteria, have the tricarboxylic acid (TCA) cycle. Recently, metabolite production using the cyanobacterial TCA cycle has been well studied. To enhance the production volume of metabolites, understanding the biochemical properties of the cyanobacterial TCA cycle is required. Generally, malate dehydrogenase oxidizes malate in the TCA cycle. However, cyanobacterial malate dehydrogenase shows low activity and does not use NADP+ as a coenzyme, unlike other cyanobacterial TCA cycle enzymes. Our analyses revealed that another malate oxidation enzyme, the malic enzyme, mainly oxidizes malate that originates from the cyanobacterial TCA cycle. These findings provide better insights into metabolite production using the cyanobacterial TCA cycle. Furthermore, our findings suggest that the enzymes related to the TCA cycle vary from organism to organism and emphasize the importance of analyses to identify the enzymes such as those performed in this study.
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Hidese R, Matsuda M, Kajikawa M, Osanai T, Kondo A, Hasunuma T. Metabolic and Microbial Community Engineering for Four-Carbon Dicarboxylic Acid Production from CO 2-Derived Glycogen in the Cyanobacterium Synechocystis sp. PCC6803. ACS Synth Biol 2022; 11:4054-4064. [PMID: 36445137 DOI: 10.1021/acssynbio.2c00379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The four-carbon (C4) dicarboxylic acids, fumarate, malate, and succinate, are the most valuable targets that must be exploited for CO2-based chemical production in the move to a sustainable low-carbon future. Cyanobacteria excrete high amounts of C4 dicarboxylic acids through glycogen fermentation in a dark anoxic environment. The enhancement of metabolic flux in the reductive TCA branch in the Cyanobacterium Synechocystis sp. PCC6803 is a key issue in the C4 dicarboxylic acid production. To improve metabolic flux through the anaplerotic pathway, we have created the recombinant strain PCCK, which expresses foreign ATP-forming phosphoenolpyruvate carboxykinase (PEPck) concurrent with intrinsic phosphoenolpyruvate carboxylase (Ppc) overexpression. Expression of PEPck concurrent with Ppc led to an increase in C4 dicarboxylic acids by autofermentation. Metabolome analysis revealed that PEPck contributed to an increase in carbon flux from hexose and pentose phosphates into the TCA reductive branch. To enhance the metabolic flux in the reductive TCA branch, we examined the effect of corn-steep liquor (CSL) as a nutritional supplement on C4 dicarboxylic acid production. Surprisingly, the addition of sterilized CSL enhanced the malate production in the PCCK strain. Thereafter, the malate and fumarate excreted by the PCCK strain are converted into succinate by the CSL-settling microorganisms. Finally, high-density cultivation of cells lacking the acetate kinase gene showed the highest production of malate and fumarate (3.2 and 2.4 g/L with sterilized CSL) and succinate (5.7 g/L with non-sterile CSL) after 72 h cultivation. The present microbial community engineering is useful for succinate production by one-pot fermentation under dark anoxic conditions.
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Affiliation(s)
- Ryota Hidese
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.,Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Mami Matsuda
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Mamiko Kajikawa
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Akihiko Kondo
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.,Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.,Research Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.,Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.,Research Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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Lai MJ, Tsai JC, Lan EI. CRISPRi-enhanced direct photosynthetic conversion of carbon dioxide to succinic acid by metabolically engineered cyanobacteria. BIORESOURCE TECHNOLOGY 2022; 366:128131. [PMID: 36252759 DOI: 10.1016/j.biortech.2022.128131] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/09/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Engineering photoautotrophic microorganisms to directly convert carbon dioxide into platform chemicals is an attractive approach for chemical sustainability and carbon mitigation. Here, an engineered cyanobacterium Synechococcus elongatus PCC 7942 was developed to produce succinic acid directly from ambient carbon dioxide. Inhibition of succinate dehydrogenase and glycogen synthase by CRIPSR interference increased carbon flux towards succinic acid. Dual inhibition of these two genes led to an 82 % increase in titer. The resulting strain produced 4.8 g/L of succinic acid in a 28-days cultivation. However, cells after the 28-days cultivation became non-viable and cannot continue production. This issue was addressed by re-inoculation with fresh cells into the production medium. This strategy enabled continuous succinic acid accumulation, reaching a final titer of 8.9 g/L. This study provides a sustainable route to succinic acid directly from carbon dioxide and a potential method to overcome the low titer limitation of cyanobacterial-based bioproduction for practical applications.
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Affiliation(s)
- Martin J Lai
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City 300, Taiwan
| | - Jemmy C Tsai
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City 300, Taiwan
| | - Ethan I Lan
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City 300, Taiwan.
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Kobayashi S, Atsumi S, Ikebukuro K, Sode K, Asano R. Light-induced production of isobutanol and 3-methyl-1-butanol by metabolically engineered cyanobacteria. Microb Cell Fact 2022; 21:7. [PMID: 34991586 PMCID: PMC8740407 DOI: 10.1186/s12934-021-01732-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/25/2021] [Indexed: 11/21/2022] Open
Abstract
Background Cyanobacteria are engineered via heterologous biosynthetic pathways to produce value-added chemicals via photosynthesis. Various chemicals have been successfully produced in engineered cyanobacteria. Chemical inducer-dependent promoters are used to induce the expression of target biosynthetic pathway genes. A chemical inducer is not ideal for large-scale reactions owing to its high cost; therefore, it is important to develop scaling-up methods to avoid their use. In this study, we designed a green light-inducible alcohol production system using the CcaS/CcaR green light gene expression system in the cyanobacterium Synechocystis sp. PCC 6803 (PCC 6803). Results To establish the green light-inducible production of isobutanol and 3-methyl-1-butanol (3MB) in PCC 6803, keto-acid decarboxylase (kdc) and alcohol dehydrogenase (adh) were expressed under the control of the CcaS/CcaR system. Increases in the transcription level were induced by irradiation with red and green light without severe effects on host cell growth. We found that the production of isobutanol and 3MB from carbon dioxide (CO2) was induced under red and green light illumination and was substantially repressed under red light illumination alone. Finally, production titers of isobutanol and 3MB reached 238 mg L−1 and 75 mg L−1, respectively, in 5 days under red and green light illumination, and these values are comparable to those reported in previous studies using chemical inducers. Conclusion A green light-induced alcohol production system was successfully integrated into cyanobacteria to produce value-added chemicals without using expensive chemical inducers. The green light-regulated production of isobutanol and 3MB from CO2 is eco-friendly and cost-effective. This study demonstrates that light regulation is a potential tool for producing chemicals and increases the feasibility of cyanobacterial bioprocesses. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01732-x.
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Affiliation(s)
- Shunichi Kobayashi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Shota Atsumi
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Kazunori Ikebukuro
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Koji Sode
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, 27599, USA
| | - Ryutaro Asano
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan.
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Kato Y, Inabe K, Hidese R, Kondo A, Hasunuma T. Metabolomics-based engineering for biofuel and bio-based chemical production in microalgae and cyanobacteria: A review. BIORESOURCE TECHNOLOGY 2022; 344:126196. [PMID: 34710610 DOI: 10.1016/j.biortech.2021.126196] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Metabolomics, an essential tool in modern synthetic biology based on the design-build-test-learn platform, is useful for obtaining a detailed understanding of cellular metabolic mechanisms through comprehensive analyses of the metabolite pool size and its dynamic changes. Metabolomics is critical to the design of a rational metabolic engineering strategy by determining the rate-limiting reaction and assimilated carbon distribution in a biosynthetic pathway of interest. Microalgae and cyanobacteria are promising photosynthetic producers of biofuels and bio-based chemicals, with high potential for developing a bioeconomic society through bio-based carbon neutral manufacturing. Metabolomics technologies optimized for photosynthetic organisms have been developed and utilized in various microalgal and cyanobacterial species. This review provides a concise overview of recent achievements in photosynthetic metabolomics, emphasizing the importance of microalgal and cyanobacterial cell factories that satisfy industrial requirements.
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Affiliation(s)
- Yuichi Kato
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Kosuke Inabe
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Ryota Hidese
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Tomohisa Hasunuma
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
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Japhalekar K, Srinivasan S, Viswanathan G, Venkatesh K. Flux balance analysis for overproduction of organic acids by Synechocystis sp. PCC 6803 under dark anoxic condition. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2021.108297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Andrews F, Faulkner M, Toogood HS, Scrutton NS. Combinatorial use of environmental stresses and genetic engineering to increase ethanol titres in cyanobacteria. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:240. [PMID: 34920731 PMCID: PMC8684110 DOI: 10.1186/s13068-021-02091-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/05/2021] [Indexed: 06/07/2023]
Abstract
Current industrial bioethanol production by yeast through fermentation generates carbon dioxide. Carbon neutral bioethanol production by cyanobacteria uses biological fixation (photosynthesis) of carbon dioxide or other waste inorganic carbon sources, whilst being sustainable and renewable. The first ethanologenic cyanobacterial process was developed over two decades ago using Synechococcus elongatus PCC 7942, by incorporating the recombinant pdc and adh genes from Zymomonas mobilis. Further engineering has increased bioethanol titres 24-fold, yet current levels are far below what is required for industrial application. At the heart of the problem is that the rate of carbon fixation cannot be drastically accelerated and carbon partitioning towards bioethanol production impacts on cell fitness. Key progress has been achieved by increasing the precursor pyruvate levels intracellularly, upregulating synthetic genes and knocking out pathways competing for pyruvate. Studies have shown that cyanobacteria accumulate high proportions of carbon reserves that are mobilised under specific environmental stresses or through pathway engineering to increase ethanol production. When used in conjunction with specific genetic knockouts, they supply significantly more carbon for ethanol production. This review will discuss the progress in generating ethanologenic cyanobacteria through chassis engineering, and exploring the impact of environmental stresses on increasing carbon flux towards ethanol production.
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Affiliation(s)
- Fraser Andrews
- EPSRC/BBSRC Future Biomanufacturing Research Hub, BBSRC/EPSRC Synthetic Biology Research Centre SYNBIOCHEM Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, Manchester, M1 7DN, UK
| | - Matthew Faulkner
- EPSRC/BBSRC Future Biomanufacturing Research Hub, BBSRC/EPSRC Synthetic Biology Research Centre SYNBIOCHEM Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, Manchester, M1 7DN, UK
| | - Helen S Toogood
- EPSRC/BBSRC Future Biomanufacturing Research Hub, BBSRC/EPSRC Synthetic Biology Research Centre SYNBIOCHEM Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, Manchester, M1 7DN, UK
| | - Nigel S Scrutton
- EPSRC/BBSRC Future Biomanufacturing Research Hub, BBSRC/EPSRC Synthetic Biology Research Centre SYNBIOCHEM Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, Manchester, M1 7DN, UK.
- C3 Biotechnologies Ltd, 20 Mannin Way, Lancaster Business Park, Caton Road, Lancaster, LA1 3SW, Lancashire, UK.
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15
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Cui J, Sun T, Chen L, Zhang W. Salt-Tolerant Synechococcus elongatus UTEX 2973 Obtained via Engineering of Heterologous Synthesis of Compatible Solute Glucosylglycerol. Front Microbiol 2021; 12:650217. [PMID: 34084156 PMCID: PMC8168540 DOI: 10.3389/fmicb.2021.650217] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/25/2021] [Indexed: 01/08/2023] Open
Abstract
The recently isolated cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) is characterized by a faster growth rate and greater tolerance to high temperature and high light, making it a good candidate chassis for autotrophic photosynthetic microbial cell factories. However, Syn2973 is sensitive to salt stress, making it urgently important to improve the salt tolerance of Syn2973 for future biotechnological applications. Glucosylglycerol, a compatible solute, plays an important role in resisting salt stress in moderate and marine halotolerant cyanobacteria. In this study, the salt tolerance of Syn2973 was successfully improved by introducing the glucosylglycerol (GG) biosynthetic pathway (OD750 improved by 24% at 60 h). In addition, the salt tolerance of Syn2973 was further enhanced by overexpressing the rate-limiting step of glycerol-3-phosphate dehydrogenase and downregulating the gene rfbA, which encodes UDP glucose pyrophosphorylase. Taken together, these results indicate that the growth of the end-point strain M-2522-GgpPS-drfbA was improved by 62% compared with the control strain M-pSI-pSII at 60 h under treatment with 0.5 M NaCl. Finally, a comparative metabolomic analysis between strains M-pSI-pSII and M-2522-GgpPS-drfbA was performed to characterize the carbon flux in the engineered M-2522-GgpPS-drfbA strain, and the results showed that more carbon flux was redirected from ADP-GLC to GG synthesis. This study provides important engineering strategies to improve salt tolerance and GG production in Syn2973 in the future.
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Affiliation(s)
- Jinyu Cui
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, China.,Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
| | - Tao Sun
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, China.,Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.,Center for Biosafety Research and Strategy, Tianjin University, Tianjin, China
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, China.,Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
| | - Weiwen Zhang
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, China.,Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China.,Center for Biosafety Research and Strategy, Tianjin University, Tianjin, China
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16
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Current knowledge and recent advances in understanding metabolism of the model cyanobacterium Synechocystis sp. PCC 6803. Biosci Rep 2021; 40:222317. [PMID: 32149336 PMCID: PMC7133116 DOI: 10.1042/bsr20193325] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
Cyanobacteria are key organisms in the global ecosystem, useful models for studying metabolic and physiological processes conserved in photosynthetic organisms, and potential renewable platforms for production of chemicals. Characterizing cyanobacterial metabolism and physiology is key to understanding their role in the environment and unlocking their potential for biotechnology applications. Many aspects of cyanobacterial biology differ from heterotrophic bacteria. For example, most cyanobacteria incorporate a series of internal thylakoid membranes where both oxygenic photosynthesis and respiration occur, while CO2 fixation takes place in specialized compartments termed carboxysomes. In this review, we provide a comprehensive summary of our knowledge on cyanobacterial physiology and the pathways in Synechocystis sp. PCC 6803 (Synechocystis) involved in biosynthesis of sugar-based metabolites, amino acids, nucleotides, lipids, cofactors, vitamins, isoprenoids, pigments and cell wall components, in addition to the proteins involved in metabolite transport. While some pathways are conserved between model cyanobacteria, such as Synechocystis, and model heterotrophic bacteria like Escherichia coli, many enzymes and/or pathways involved in the biosynthesis of key metabolites in cyanobacteria have not been completely characterized. These include pathways required for biosynthesis of chorismate and membrane lipids, nucleotides, several amino acids, vitamins and cofactors, and isoprenoids such as plastoquinone, carotenoids, and tocopherols. Moreover, our understanding of photorespiration, lipopolysaccharide assembly and transport, and degradation of lipids, sucrose, most vitamins and amino acids, and haem, is incomplete. We discuss tools that may aid our understanding of cyanobacterial metabolism, notably CyanoSource, a barcoded library of targeted Synechocystis mutants, which will significantly accelerate characterization of individual proteins.
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Ito S, Hakamada T, Ogino T, Osanai T. Reconstitution of oxaloacetate metabolism in the tricarboxylic acid cycle in Synechocystis sp. PCC 6803: discovery of important factors that directly affect the conversion of oxaloacetate. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1449-1458. [PMID: 33280178 DOI: 10.1111/tpj.15120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 06/12/2023]
Abstract
The tricarboxylic acid (TCA) cycle is one of the most important metabolic pathways in nature. Oxygenic photoautotrophic bacteria, cyanobacteria, have an unusual TCA cycle. The TCA cycle in cyanobacteria contains two unique enzymes that are not part of the TCA cycle in other organisms. In recent years, sustainable metabolite production from carbon dioxide using cyanobacteria has been looked at as a means to reduce the environmental burden of this gas. Among cyanobacteria, the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803) is an optimal host for sustainable metabolite production. Recently, metabolite production using the TCA cycle in Synechocystis 6803 has been carried out. Previous studies revealed that the branch point of the oxidative and reductive TCA cycles, oxaloacetate metabolism, plays a key role in metabolite production. However, the biochemical mechanisms regulating oxaloacetate metabolism in Synechocystis 6803 are poorly understood. Concentrations of oxaloacetate in Synechocystis 6803 are extremely low, such that in vivo analysis of oxaloacetate metabolism does not seem realistic. Therefore, using purified enzymes, we reconstituted oxaloacetate metabolism in Synechocystis 6803 in vitro to reveal the regulatory mechanisms involved. Reconstitution of oxaloacetate metabolism revealed that pH, Mg2+ and phosphoenolpyruvate are important factors affecting the conversion of oxaloacetate in the TCA cycle. Biochemical analyses of the enzymes involved in oxaloacetate metabolism in this and previous studies revealed the biochemical mechanisms underlying the effects of these factors on oxaloacetate conversion. In addition, we clarified the function of two l-malate dehydrogenase isozymes in oxaloacetate metabolism. These findings serve as a basis for various applications of the cyanobacterial TCA cycle.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Takumi Hakamada
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Tatsumi Ogino
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
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18
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Verhage L. Living microfactories. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1447-1448. [PMID: 33772901 DOI: 10.1111/tpj.15213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
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19
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Durall C, Kukil K, Hawkes JA, Albergati A, Lindblad P, Lindberg P. Production of succinate by engineered strains of Synechocystis PCC 6803 overexpressing phosphoenolpyruvate carboxylase and a glyoxylate shunt. Microb Cell Fact 2021; 20:39. [PMID: 33557832 PMCID: PMC7871529 DOI: 10.1186/s12934-021-01529-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/25/2021] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Cyanobacteria are promising hosts for the production of various industrially important compounds such as succinate. This study focuses on introduction of the glyoxylate shunt, which is naturally present in only a few cyanobacteria, into Synechocystis PCC 6803. In order to test its impact on cell metabolism, engineered strains were evaluated for succinate accumulation under conditions of light, darkness and anoxic darkness. Each condition was complemented by treatments with 2-thenoyltrifluoroacetone, an inhibitor of succinate dehydrogenase enzyme, and acetate, both in nitrogen replete and deplete medium. RESULTS We were able to introduce genes encoding the glyoxylate shunt, aceA and aceB, encoding isocitrate lyase and malate synthase respectively, into a strain of Synechocystis PCC 6803 engineered to overexpress phosphoenolpyruvate carboxylase. Our results show that complete expression of the glyoxylate shunt results in higher extracellular succinate accumulation compared to the wild type control strain after incubation of cells in darkness and anoxic darkness in the presence of nitrate. Addition of the inhibitor 2-thenoyltrifluoroacetone increased succinate titers in all the conditions tested when nitrate was available. Addition of acetate in the presence of the inhibitor further increased the succinate accumulation, resulting in high levels when phosphoenolpyruvate carboxylase was overexpressed, compared to control strain. However, the highest succinate titer was obtained after dark incubation of an engineered strain with a partial glyoxylate shunt overexpressing isocitrate lyase in addition to phosphoenolpyruvate carboxylase, with only 2-thenoyltrifluoroacetone supplementation to the medium. CONCLUSIONS Heterologous expression of the glyoxylate shunt with its central link to the tricarboxylic acid cycle (TCA) for acetate assimilation provides insight on the coordination of the carbon metabolism in the cell. Phosphoenolpyruvate carboxylase plays an important role in directing carbon flux towards the TCA cycle.
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Affiliation(s)
- Claudia Durall
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Kateryna Kukil
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Jeffrey A Hawkes
- Analytical Chemistry, Department of Chemistry-BMC, Uppsala University, Box 599, 751 20, Uppsala, Sweden
| | - Alessia Albergati
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Pia Lindberg
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20, Uppsala, Sweden.
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20
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Metabolic Engineering and Synthetic Biology of Cyanobacteria for Carbon Capture and Utilization. BIOTECHNOL BIOPROC E 2020. [DOI: 10.1007/s12257-019-0447-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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21
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Srivastava A, Varshney RK, Shukla P. Sigma Factor Modulation for Cyanobacterial Metabolic Engineering. Trends Microbiol 2020; 29:266-277. [PMID: 33229204 DOI: 10.1016/j.tim.2020.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 11/18/2022]
Abstract
Sigma (σ) factors are key regulatory proteins that control the transcription initiation in prokaryotes. In response to environmental or developmental cues, σ factors initiate the transcription of necessary genes responsible for maintaining a life-sustaining metabolic balance. Due to the significant role of σ factors in bacterial metabolism, their rational engineering for commercial metabolite production in photoautotrophic, cyanobacterial cells is a desirable venture. As cyanobacterial genomes typically encode multiple σ factors, effective execution of metabolic engineering efforts largely relies on uncovering the complicated gene regulatory network and further characterization of the members of σ factor regulatory circuits. This review outlines the prospects of σ factor in metabolic engineering of cyanobacteria, summarizes the challenges in the path towards an efficient strain construction and highlights the genomic context of putative regulators of cyanobacterial σ factors.
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Affiliation(s)
- Amit Srivastava
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Rajeev K Varshney
- Center of Excellence in Genomics and Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak-124001, Haryana, India.
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22
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Unconventional biochemical regulation of the oxidative pentose phosphate pathway in the model cyanobacterium Synechocystis sp. PCC 6803. Biochem J 2020; 477:1309-1321. [PMID: 32227111 DOI: 10.1042/bcj20200038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/11/2020] [Accepted: 03/30/2020] [Indexed: 01/05/2023]
Abstract
Metabolite production from carbon dioxide using sugar catabolism in cyanobacteria has been in the spotlight recently. Synechocystis sp. PCC 6803 (Synechocystis 6803) is the most studied cyanobacterium for metabolite production. Previous in vivo analyses revealed that the oxidative pentose phosphate (OPP) pathway is at the core of sugar catabolism in Synechocystis 6803. However, the biochemical regulation of the OPP pathway enzymes in Synechocystis 6803 remains unknown. Therefore, we characterized a key enzyme of the OPP pathway, glucose-6-phosphate dehydrogenase (G6PDH), and related enzymes from Synechocystis 6803. Synechocystis 6803 G6PDH was inhibited by citrate in the oxidative tricarboxylic acid (TCA) cycle. Citrate has not been reported as an inhibitor of G6PDH before. Similarly, 6-phosphogluconate dehydrogenase, the other enzyme from Synechocystis 6803 that catalyzes the NADPH-generating reaction in the OPP pathway, was inhibited by citrate. To understand the physiological significance of this inhibition, we characterized succinic semialdehyde dehydrogenase (SSADH) from Synechocystis 6803 (SySSADH), which catalyzes one of the NAD(P)H generating reactions in the oxidative TCA cycle. Similar to isocitrate dehydrogenase from Synechocystis 6803, SySSADH specifically catalyzed the NADPH-generating reaction and was not inhibited by citrate. The activity of SySSADH was lower than that of other bacterial SSADHs. Previous and this studies revealed that unlike the OPP pathway, the oxidative TCA cycle is a pathway with low efficiency in NADPH generation in Synechocystis 6803. It has, thus, been suggested that to avoid NADPH overproduction, the OPP pathway dehydrogenase activity is repressed when the flow of the oxidative TCA cycle increases in Synechocystis 6803.
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Ito S, Iwazumi K, Sukigara H, Osanai T. Fumarase From Cyanidioschyzon merolae Stably Shows High Catalytic Activity for Fumarate Hydration Under High Temperature Conditions. Front Microbiol 2020; 11:2190. [PMID: 33042040 PMCID: PMC7525151 DOI: 10.3389/fmicb.2020.560894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/18/2020] [Indexed: 01/01/2023] Open
Abstract
Fumarases (Fums) catalyze the reversible reaction converting fumarate to l-malate. There are two kinds of Fums: Class І and ІІ. Thermostable Class ІІ Fums, from mesophilic microorganisms, are utilized for industrial l-malate production. However, the low thermostability of these Fums is a limitation in industrial l-malate production. Therefore, an alternative Class ІІ Fum that shows high activity and thermostability is required to overcome this drawback. Thermophilic microalgae and cyanobacteria can use carbon dioxide as a carbon source and are easy to cultivate. Among them, Cyanidioschyzon merolae and Thermosynechococcus elongatus are model organisms to study cell biology and structural biology, respectively. We biochemically analyzed Class ІІ Fums from C. merolae (CmFUM) and T. elongatus (TeFum). Both CmFUM and TeFum preferentially catalyzed fumarate hydration. The catalytic activity of CmFUM for fumarate hydration in the optimum conditions (52°C and pH 7.5) is higher compared to those of Class ІІ Fums from other organisms and TeFum. Thermostability tests of CmFUM revealed that CmFUM showed higher thermostability than those of Class ІІ Fums from other microorganisms. The yield of l-malate obtained from fumarate hydration catalyzed by CmFUM was 75-81%. In summary, CmFum has suitable properties for efficient l-malate production.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, Kawasaki, Japan
| | - Kaori Iwazumi
- School of Agriculture, Meiji University, Kawasaki, Japan
| | | | - Takashi Osanai
- School of Agriculture, Meiji University, Kawasaki, Japan
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24
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Mock M, Schmid A, Bühler K. Directed Reaction Engineering Boosts Succinate Formation of Synechocystis sp. PCC 6803_Δsll1625. Biotechnol J 2020; 15:e2000127. [PMID: 32845563 DOI: 10.1002/biot.202000127] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/10/2020] [Indexed: 11/07/2022]
Abstract
It is known that Synechocystis sp. PCC 6803 carrying a partial deletion of the succinate dehydrogenase (Synechocystis_∆sll1625) secretes succinate during aerobic cultivation with continuous illumination and in the presence of CO2 . Maximal succinate titers of 2 mM (236 mg L-1 ) are reported. CO2 is identified as a crucial parameter for product formation, however, a detailed characterization of different cultivation conditions is still missing. Here the focus is on further reaction engineering to improve the photoautotrophic production of succinate using Synechocystis_∆sll1625. Therefore the impact of light availability, illumination regimes, nutrient availability, and external pH on product formation are investigated. Results obtained in this study reveal the importance of these parameters on the formation of succinate and cultivation with light/dark cycles increases the succinate concentration to 3 mM (354 mg L-1 ) after 28 days of cultivation. Furthermore, cultivation in unbuffered medium under ambient CO2 conditions even doubled the final succinate titer to 4 mM (472 mg L-1 ) after 28 days. Taking biomass concentrations into account, a maximal yield of succinate on biomass of 215 mgSucc gCDW -1 is achieved, which is the highest so far reported for the production of succinate utilizing Synechocystis as host organism.
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Affiliation(s)
- Magdalena Mock
- Department Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Leipzig, 04318, Germany
| | - Andreas Schmid
- Department Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Leipzig, 04318, Germany
| | - Katja Bühler
- Department Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Leipzig, 04318, Germany
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Photosynthetic Co-Production of Succinate and Ethylene in A Fast-Growing Cyanobacterium, Synechococcus elongatus PCC 11801. Metabolites 2020; 10:metabo10060250. [PMID: 32560048 PMCID: PMC7345232 DOI: 10.3390/metabo10060250] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/21/2020] [Accepted: 06/12/2020] [Indexed: 12/13/2022] Open
Abstract
Cyanobacteria are emerging as hosts for photoautotrophic production of chemicals. Recent studies have attempted to stretch the limits of photosynthetic production, typically focusing on one product at a time, possibly to minimise the additional burden of product separation. Here, we explore the simultaneous production of two products that can be easily separated: ethylene, a gaseous product, and succinate, an organic acid that accumulates in the culture medium. This was achieved by expressing a single copy of the ethylene forming enzyme (efe) under the control of PcpcB, the inducer-free super-strong promoter of phycocyanin β subunit. We chose the recently reported, fast-growing and robust cyanobacterium, Synechococcus elongatus PCC 11801, as the host strain. A stable recombinant strain was constructed using CRISPR-Cpf1 in a first report of markerless genome editing of this cyanobacterium. Under photoautotrophic conditions, the recombinant strain shows specific productivities of 338.26 and 1044.18 μmole/g dry cell weight/h for ethylene and succinate, respectively. These results compare favourably with the reported productivities for individual products in cyanobacteria that are highly engineered. Metabolome profiling and 13C labelling studies indicate carbon flux redistribution and suggest avenues for further improvement. Our results show that S. elongatus PCC 11801 is a promising candidate for metabolic engineering.
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26
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Characterization of a novel marine unicellular alga, Pseudoneochloris sp. strain NKY372003 as a high carbohydrate producer. J Biosci Bioeng 2020; 129:687-692. [DOI: 10.1016/j.jbiosc.2019.12.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 12/21/2022]
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27
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Sake CL, Newman DM, Boyle NR. Evaluation of quenching methods for metabolite recovery in photoautotrophic Synechococcus sp. PCC 7002. Biotechnol Prog 2020; 36:e3015. [PMID: 32388924 DOI: 10.1002/btpr.3015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/07/2020] [Accepted: 05/05/2020] [Indexed: 12/29/2022]
Abstract
The first step of many metabolomics studies is quenching, a technique vital for rapidly halting metabolism and ensuring that the metabolite profile remains unchanging during sample processing. The most widely used approach is to plunge the sample into prechilled cold methanol; however, this led to significant metabolite loss in Synecheococcus sp. PCC 7002. Here we describe our analysis of the impacts of cold methanol quenching on the model marine cyanobacterium Synechococcus sp. PCC 7002, as well as our brief investigation of alternative quenching methods. We tested several methods including cold methanol, cold saline, and two filtration approaches. Targeted central metabolites were extracted and metabolomic profiles were generated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicate that cold methanol quenching induces dramatic metabolite leakage in Synechococcus, resulting in a majority of central metabolites being lost prior to extraction. Alternatively, usage of a chilled saline quenching solution mitigates metabolite leakage and improves sample recovery without sacrificing rapid quenching of cellular metabolism. Finally, we illustrate that metabolite leakage can be assessed, and subsequently accounted for, in order to determine absolute metabolite pool sizes; however, our results show that metabolite leakage is inconsistent across various metabolite pools and therefore must be determined for each individually measured metabolite.
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Affiliation(s)
- Cara L Sake
- Chemical & Biological Engineering , Colorado School of Mines, Golden, Colorado, USA
| | - Darrian M Newman
- Chemical & Biological Engineering , Colorado School of Mines, Golden, Colorado, USA
| | - Nanette R Boyle
- Chemical & Biological Engineering , Colorado School of Mines, Golden, Colorado, USA
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28
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Scholl J, Dengler L, Bader L, Forchhammer K. Phosphoenolpyruvate carboxylase from the cyanobacterium Synechocystis sp. PCC 6803 is under global metabolic control by P II signaling. Mol Microbiol 2020; 114:292-307. [PMID: 32274833 DOI: 10.1111/mmi.14512] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/20/2022]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is the second major carbon-fixing enzyme in photoautotrophic organisms. PEPC is required for the synthesis of amino acids of the glutamate and aspartate family by replenishing the TCA cycle. Furthermore, in cyanobacteria, PEPC, together with malate dehydrogenase and malic enzyme, forms a metabolic shunt for the synthesis of pyruvate from PEP. During this process, CO2 is first fixed and later released again. Due to its central metabolic position, it is crucial to fully understand the regulation of PEPC. Here, we identify PEPC from the cyanobacterium Synechocystis sp. PCC 6803 (PEPC) as a novel interaction partner for the global signal transduction protein PII . In addition to an extensive characterization of PEPC, we demonstrate specific PII -PEPC complex formation and its enzymatic consequences. PEPC activity is tuned by the metabolite-sensing properties of PII : Whereas in the absence of PII, PEPC is subjected to ATP inhibition, it is activated beyond its basal activity in the presence of PII . Furthermore, PII -PEPC complex formation is inhibited by ADP and PEPC activation by PII -ATP is mitigated in the presence of 2-OG, linking PEPC regulation to the cell's global carbon/nitrogen status. Finally, physiological relevance of the in vitro measurements was proven by metabolomic analyses of Synechocystis wild-type and PII -deficient cells.
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Affiliation(s)
- Jörg Scholl
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls University, Tübingen, Germany
| | - Lisa Dengler
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls University, Tübingen, Germany
| | - Laura Bader
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls University, Tübingen, Germany
| | - Karl Forchhammer
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls University, Tübingen, Germany
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Iijima H, Watanabe A, Sukigara H, Shirai T, Kondo A, Osanai T. Simultaneous increases in the levels of compatible solutes by cost-effective cultivation of Synechocystis sp. PCC 6803. Biotechnol Bioeng 2020; 117:1649-1660. [PMID: 32129469 DOI: 10.1002/bit.27324] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/27/2020] [Accepted: 03/03/2020] [Indexed: 12/27/2022]
Abstract
Synechocystis sp. PCC 6803, a cyanobacterium widely used for basic research, is often cultivated in a synthetic medium, BG-11, in the presence of 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid (HEPES) or 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid buffer. Owing to the high cost of HEPES buffer (96.9% of the total cost of BG-11 medium), the biotechnological application of BG-11 is limited. In this study, we cultured Synechocystis sp. PCC 6803 cells in BG-11 medium without HEPES buffer and examined the effects on the primary metabolism. Synechocystis sp. PCC 6803 cells could grow in BG-11 medium without HEPES buffer after adjusting for nitrogen sources and light intensity; the production rate reached 0.54 g cell dry weight·L-1 ·day-1 , exceeding that of commercial cyanobacteria and Synechocystis sp. PCC 6803 cells cultivated under other conditions. The exclusion of HEPES buffer markedly altered the metabolites in the central carbon metabolism; particularly, the levels of compatible solutes, such as sucrose, glucosylglycerol, and glutamate were increased. Although the accumulation of sucrose and glucosylglycerol under high salt conditions is antagonistic to each other, these metabolites accumulated simultaneously in cells grown in the cost-effective medium. Because these metabolites are used in industrial feedstocks, our results reveal the importance of medium composition for the production of metabolites using cyanobacteria.
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Affiliation(s)
- Hiroko Iijima
- Department of Agricultural Chemistrym School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
| | - Atsuko Watanabe
- Department of Agricultural Chemistrym School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
| | - Haruna Sukigara
- Department of Agricultural Chemistrym School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
| | - Tomokazu Shirai
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
| | - Akihiko Kondo
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan.,Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Takashi Osanai
- Department of Agricultural Chemistrym School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
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30
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Hidese R, Matsuda M, Osanai T, Hasunuma T, Kondo A. Malic Enzyme Facilitates d-Lactate Production through Increased Pyruvate Supply during Anoxic Dark Fermentation in Synechocystis sp. PCC 6803. ACS Synth Biol 2020; 9:260-268. [PMID: 32004431 DOI: 10.1021/acssynbio.9b00281] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
d-Lactate is one of the most valuable compounds for manufacturing biobased polymers. Here, we have investigated the significance of endogenous malate dehydrogenase (decarboxylating) (malic enzyme, ME), which catalyzes the oxidative decarboxylation of malate to pyruvate, in d-lactate biosynthesis in the cyanobacterium Synechocystis sp. PCC6803. d-Lactate levels were increased by 2-fold in ME-overexpressing strains, while levels in ME-deficient strains were almost equivalent to those in the host strain. Dynamic metabolomics revealed that overexpression of ME led to increased turnover rates in malate and pyruvate metabolism; in contrast, deletion of ME resulted in increased pool sizes of glycolytic intermediates, probably due to sequential feedback inhibition, initially triggered by malate accumulation. Finally, both the loss of the acetate kinase gene and overexpression of endogenous d-lactate dehydrogenase, concurrent with ME overexpression, resulted in the highest production of d-lactate (26.6 g/L) with an initial cell concentration of 75 g-DCW/L after 72 h fermentation.
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Affiliation(s)
- Ryota Hidese
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Mami Matsuda
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Akihiko Kondo
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
- Biomass Engineering Program, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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31
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Kobayashi S, Nakajima M, Asano R, Ferreira EA, Abe K, Tamagnini P, Atsumi S, Sode K. Application of an engineered chromatic acclimation sensor for red-light-regulated gene expression in cyanobacteria. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101691] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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32
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Mock M, Schmid A, Bühler K. Photoautotrophic production of succinate via the oxidative branch of the tricarboxylic acid cycle influences glycogen accumulation in Synechocystis sp. PCC 6803. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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33
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Ito S, Koyama N, Osanai T. Citrate synthase from Synechocystis is a distinct class of bacterial citrate synthase. Sci Rep 2019; 9:6038. [PMID: 30988396 PMCID: PMC6465352 DOI: 10.1038/s41598-019-42659-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/04/2019] [Indexed: 12/03/2022] Open
Abstract
Citrate synthase (CS, EC 2.3.3.1) catalyses the initial reaction of the tricarboxylic acid (TCA) cycle. Although CSs from heterotrophic bacteria have been extensively studied, cyanobacterial CSs are not well-understood. Cyanobacteria can produce various metabolites from carbon dioxide. Synechocystis sp. PCC 6803 (Synechocystis 6803) is a cyanobacterium used to synthesize metabolites through metabolic engineering techniques. The production of acetyl-CoA-derived metabolites in Synechocystis 6803 has been widely examined. However, the biochemical mechanisms of reactions involving acetyl-CoA in Synechocystis 6803 are poorly understood. We characterised the CS from Synechocystis 6803 (SyCS) and compared its characteristics with other bacterial CSs. SyCS catalysed only the generation of citrate, and did not catalyse the cleavage of citrate. It is suggested that SyCS is not related to the reductive TCA cycle. The substrate affinity and turnover number of SyCS were lower than those of CSs from heterotrophic bacteria. SyCS was activated by MgCl2 and CaCl2, which inhibit various bacterial CSs. SyCS was not inhibited by ATP and NADH; which are typical feedback inhibitors of other bacterial CSs. SyCS was inhibited by phosphoenolpyruvate and activated by ADP, which has not been reported for CSs from heterotrophic bacteria. Thus, SyCS showed unique characteristics, particularly its sensitivity to effectors.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Naoto Koyama
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan.
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Maruyama M, Nishiguchi H, Toyoshima M, Okahashi N, Matsuda F, Shimizu H. Time-resolved analysis of short term metabolic adaptation at dark transition in Synechocystis sp. PCC 6803. J Biosci Bioeng 2019; 128:424-428. [PMID: 30979614 DOI: 10.1016/j.jbiosc.2019.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/25/2019] [Accepted: 03/25/2019] [Indexed: 12/22/2022]
Abstract
In photosynthetic organisms, such as cyanobacteria, ATP and NADPH are generated through the light reaction, and then are used for CO2 fixation in the dark reaction. As light intensity always fluctuates under natural conditions, balancing the cofactor regeneration and consumption is essential to maintain active CO2 fixation as well as for metabolic engineering of strains that produce biochemicals. In this study, a time-resolved metabolome analysis of Synechocystis sp. PCC 6803 (PCC6803) was conducted to investigate a metabolic adaptation at 0-15 min after a sudden shift from light to dark conditions. Rapid accumulation of sedoheptulose 7-phosphate, ribulose 5-phosphate, xylulose 5-phosphate, and 6-phosphogluconate suggested that the central metabolism of PCC6803 was regulated by inactivation of phosphoribulokinase and activation of glucose-6-phosphate dehydrogenase (G6PDH) probably via the redox regulation. The culture and metabolic profile of the Δzwf strain lacking G6PDH showed that the role of G6PDH in regeneration of NADPH could be complemented by the activation of isocitrate dehydrogenase in the TCA cycle, indicating the importance of the rapid regulation of NADPH regeneration after the shift to dark conditions. The mechanism underlying metabolic regulation is also useful for metabolic engineering of PCC6803, as the Δzwf strain produced higher amount of organic acids than wild type.
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Affiliation(s)
- Masaharu Maruyama
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Hiroki Nishiguchi
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Masakazu Toyoshima
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Nobuyuki Okahashi
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Fumio Matsuda
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Hiroshi Shimizu
- Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Qiao C, Zhang M, Luo Q, Lu X. Identification of two two-component signal transduction mutants with enhanced sucrose biosynthesis in Synechococcus elongatus PCC 7942. J Basic Microbiol 2019; 59:465-476. [PMID: 30802333 DOI: 10.1002/jobm.201800676] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/13/2019] [Accepted: 01/25/2019] [Indexed: 12/19/2022]
Abstract
Metabolic engineering of the freshwater cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942), synthesizing sucrose as the only compatible solute upon salt stress, has greatly improved its sucrose productivity. However, the signaling and regulatory mechanisms of this physiological process are still unknown. To know more about these aspects, a library of inactivation mutants for all 44 predicted signal transduction genes of Syn7942 was constructed. By evaluating sucrose production, two two-component signal transduction mutants Δ1125 and Δ1404, in which Synpcc7942_1125 and Synpcc7942_1404 was inactivated, respectively, were identified. They exhibited stably enhanced sucrose production, but the growth and the expression of sps encoding sucrose-phosphate synthase under salt stress were not affected, indicating that the corresponding signal transduction proteins do not regulate salt-induced sucrose synthesis by directly regulating sps expression. Moreover, the glycogen accumulation was enhanced in Δ1125 and Δ1404, and the salt stress-intensified photodamage of these mutants was also found to be relieved. These results indicated that the basic cell metabolisms such as glycogen metabolism and photosynthesis of the mutants were affected by gene inactivation, which might further affect salt-induced sucrose synthesis. Further studies on gene functions and signaling pathways or networks of Synpcc7942_1125 and Synpcc7942_1404 would reveal more details about the molecular bases for the observed phenotypes of Δ1125 and Δ1404.
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Affiliation(s)
- Cuncun Qiao
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Mingyi Zhang
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China.,Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Quan Luo
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Xuefeng Lu
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,Marine Biology and Biotechnology Laboratory, Qingdao National Laboratory for Marine Science and Technology, Aoshanwei, Qingdao, China
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36
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Tomita Y, Takeya M, Suzuki K, Nitta N, Higuchi C, Marukawa-Hashimoto Y, Osanai T. Amino acid excretion from Euglena gracilis cells in dark and anaerobic conditions. ALGAL RES 2019. [DOI: 10.1016/j.algal.2018.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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37
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Ito S, Osanai T. Single Amino Acid Change in 6-Phosphogluconate Dehydrogenase from Synechocystis Conveys Higher Affinity for NADP+ and Altered Mode of Inhibition by NADPH. PLANT & CELL PHYSIOLOGY 2018; 59:2452-2461. [PMID: 30107441 DOI: 10.1093/pcp/pcy165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 08/07/2018] [Indexed: 06/08/2023]
Abstract
In the oxidative pentose phosphate pathway, 6-phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) is one of the enzymes that catalyzes reactions generating NADPH. The model cyanobacterium Synechocystis sp. PCC 6803 is widely studied for numerous applications; however, biochemical knowledge of the NADPH production pathway in Synechocystis sp. PCC 6803 is limited. In this study, we conducted biochemical analysis of a 6-phosphogluconate dehydrogenase from Synechocystis sp. PCC 6803 (Sy6PGDH). We found that Sy6PGDH has unconventional characteristics, i.e. the highest kcat value and non-competitive inhibition by NADPH. Additionally, phylogenetic analysis of cyanobacterial 6PGDHs revealed that an amino acid residue at position 42 in Sy6PGDH is highly conserved for each order of cyanobacteria, but Sy6PGDH is phylogenetically unique. In Sy6PGDH, a single amino acid substitution at position 42 from serine to threonine enhanced the affinity for NADP+ and altered the mode of inhibition by NADPH. The amino acid substitution equivalent to Ser42 also altered the affinity for NADP+ and mode of inhibition by NADPH in Arthrospira platensis. These data suggested that an amino acid residue corresponding to position 42 in Sy6PGDH is one of the important residues that possibly determines the function of cyanobacterial 6PGDHs.
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Affiliation(s)
- Shoki Ito
- Department of Agricultural Chemistry School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku Kawasaki, Kanagawa, Japan
| | - Takashi Osanai
- Department of Agricultural Chemistry School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku Kawasaki, Kanagawa, Japan
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38
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Takeya M, Ito S, Sukigara H, Osanai T. Purification and Characterisation of Malate Dehydrogenase From Synechocystis sp. PCC 6803: Biochemical Barrier of the Oxidative Tricarboxylic Acid Cycle. FRONTIERS IN PLANT SCIENCE 2018; 9:947. [PMID: 30057585 PMCID: PMC6053527 DOI: 10.3389/fpls.2018.00947] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
Cyanobacteria possess an atypical tricarboxylic acid (TCA) cycle with various bypasses. Previous studies have suggested that a cyclic flow through the TCA cycle is not essential for cyanobacteria under normal growth conditions. The cyanobacterial TCA cycle is, thus, different from that in other bacteria, and the biochemical properties of enzymes in this TCA cycle are less understood. In this study, we reveal the biochemical characteristics of malate dehydrogenase (MDH) from Synechocystis sp. PCC 6803 MDH (SyMDH). The optimal temperature of SyMDH activity was 45-50°C and SyMDH was more thermostable than MDHs from other mesophilic microorganisms. The optimal pH of SyMDH varied with the direction of the reaction: pH 8.0 for the oxidative reaction and pH 6.5 for the reductive reaction. The reductive reaction catalysed by SyMDH was activated by magnesium ions and fumarate, indicating that SyMDH is regulated by a positive feedback mechanism. The Km-value of SyMDH for malate was approximately 210-fold higher than that for oxaloacetate and the Km-value for NAD+ was approximately 19-fold higher than that for NADH. The catalytic efficiency of SyMDH for the reductive reaction, deduced from kcat-values, was also higher than that for the oxidative reaction. These results indicate that SyMDH is more efficient in the reductive reaction in the TCA cycle, and it plays key roles in determining the direction of the TCA cycle in this cyanobacterium.
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Hasunuma T, Matsuda M, Kato Y, Vavricka CJ, Kondo A. Temperature enhanced succinate production concurrent with increased central metabolism turnover in the cyanobacterium Synechocystis sp. PCC 6803. Metab Eng 2018; 48:109-120. [DOI: 10.1016/j.ymben.2018.05.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/25/2018] [Accepted: 05/25/2018] [Indexed: 12/22/2022]
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40
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Tailoring cyanobacterial cell factory for improved industrial properties. Biotechnol Adv 2018; 36:430-442. [DOI: 10.1016/j.biotechadv.2018.01.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 01/07/2018] [Accepted: 01/08/2018] [Indexed: 11/20/2022]
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41
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Ueda K, Nakajima T, Yoshikawa K, Toya Y, Matsuda F, Shimizu H. Metabolic flux of the oxidative pentose phosphate pathway under low light conditions in Synechocystis sp. PCC 6803. J Biosci Bioeng 2018; 126:38-43. [PMID: 29499995 DOI: 10.1016/j.jbiosc.2018.01.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/15/2018] [Accepted: 01/30/2018] [Indexed: 10/17/2022]
Abstract
The role of the oxidative pentose phosphate pathway (oxPPP) in Synechocystis sp. PCC 6803 under mixotrophic conditions was investigated by 13C metabolic flux analysis. Cells were cultured under low (10 μmol m-2 s-1) and high light intensities (100 μmol m-2 s-1) in the presence of glucose. The flux of CO2 fixation by ribulose bisphosphate carboxylase/oxygenase under the high light condition was approximately 3-fold higher than that under the low light condition. Although no flux of the oxPPP was observed under the high light condition, flux of 0.08-0.19 mmol gDCW-1 h-1 in the oxPPP was observed under the low light condition. The balance between the consumption and production of NADPH suggested that approximately 10% of the total NADPH production was generated by the oxPPP under the low light condition. The growth phenotype of a mutant with deleted zwf, which encodes glucose-6-phosphate dehydrogenase in the oxPPP, was compared to that of the parental strain under low and high light conditions. Growth of the Δzwf mutant nearly stopped during the late growth phase under the low light condition, whereas the growth rates of the two strains were identical under the high light condition. These results indicate that NADPH production in the oxPPP is essential for anabolism under low light conditions. The oxPPP appears to play an important role in producing NADPH from glucose and ATP to compensate for NADPH shortage under low light conditions.
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Affiliation(s)
- Kentaro Ueda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Tsubasa 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.
| | - Fumio Matsuda
- 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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Stensjö K, Vavitsas K, Tyystjärvi T. Harnessing transcription for bioproduction in cyanobacteria. PHYSIOLOGIA PLANTARUM 2018; 162:148-155. [PMID: 28762505 DOI: 10.1111/ppl.12606] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/04/2017] [Accepted: 07/10/2017] [Indexed: 06/07/2023]
Abstract
Sustainable production of biofuels and other valuable compounds is one of our future challenges. One tempting possibility is to use photosynthetic cyanobacteria as production factories. Currently, tools for genetic engineering of cyanobacteria are not good enough to exploit the full potential of cyanobacteria. A wide variety of expression systems will be required to adjust both the expression of heterologous enzyme(s) and metabolic routes to the best possible balance, allowing the optimal production of a particular substance. In bacteria, transcription, especially the initiation of transcription, has a central role in adjusting gene expression and thus also metabolic fluxes of cells according to environmental cues. Here we summarize the recent progress in developing tools for efficient cyanofactories, focusing especially on transcriptional regulation.
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Affiliation(s)
- Karin Stensjö
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden
| | - Konstantinos Vavitsas
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Taina Tyystjärvi
- Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
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43
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Production of Bioplastic Compounds by Genetically Manipulated and Metabolic Engineered Cyanobacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1080:155-169. [DOI: 10.1007/978-981-13-0854-3_7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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44
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Asplund-Samuelsson J, Janasch M, Hudson EP. Thermodynamic analysis of computed pathways integrated into the metabolic networks of E. coli and Synechocystis reveals contrasting expansion potential. Metab Eng 2017; 45:223-236. [PMID: 29278749 DOI: 10.1016/j.ymben.2017.12.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 12/04/2017] [Accepted: 12/20/2017] [Indexed: 01/09/2023]
Abstract
Introducing biosynthetic pathways into an organism is both reliant on and challenged by endogenous biochemistry. Here we compared the expansion potential of the metabolic network in the photoautotroph Synechocystis with that of the heterotroph E. coli using the novel workflow POPPY (Prospecting Optimal Pathways with PYthon). First, E. coli and Synechocystis metabolomic and fluxomic data were combined with metabolic models to identify thermodynamic constraints on metabolite concentrations (NET analysis). Then, thousands of automatically constructed pathways were placed within each network and subjected to a network-embedded variant of the max-min driving force analysis (NEM). We found that the networks had different capabilities for imparting thermodynamic driving forces toward certain compounds. Key metabolites were constrained differently in Synechocystis due to opposing flux directions in glycolysis and carbon fixation, the forked tri-carboxylic acid cycle, and photorespiration. Furthermore, the lysine biosynthesis pathway in Synechocystis was identified as thermodynamically constrained, impacting both endogenous and heterologous reactions through low 2-oxoglutarate levels. Our study also identified important yet poorly covered areas in existing metabolomics data and provides a reference for future thermodynamics-based engineering in Synechocystis and beyond. The POPPY methodology represents a step in making optimal pathway-host matches, which is likely to become important as the practical range of host organisms is diversified.
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Affiliation(s)
- Johannes Asplund-Samuelsson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Markus Janasch
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Elton P Hudson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
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45
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Ito S, Takeya M, Osanai T. Substrate Specificity and Allosteric Regulation of a D-Lactate Dehydrogenase from a Unicellular Cyanobacterium are Altered by an Amino Acid Substitution. Sci Rep 2017; 7:15052. [PMID: 29118438 PMCID: PMC5678113 DOI: 10.1038/s41598-017-15341-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 10/25/2017] [Indexed: 01/11/2023] Open
Abstract
Lactate/lactic acid is an important chemical compound for the manufacturing of bioplastics. The unicellular cyanobacterium Synechocystis sp. PCC 6803 can produce lactate from carbon dioxide and possesses d-lactate dehydrogenase (Ddh). Here, we performed a biochemical analysis of the Ddh from this cyanobacterium (SyDdh) using recombinant proteins. SyDdh was classified into a cyanobacterial clade similar to those from Gram-negative bacteria, although it was distinct from them. SyDdh can use both pyruvate and oxaloacetate as a substrate and is activated by fructose-1,6-bisphosphate and repressed by divalent cations. An amino acid substitution based on multiple sequence alignment data revealed that the glutamine at position 14 and serine at position 234 are important for the allosteric regulation by Mg2+ and substrate specificity of SyDdh, respectively. These results reveal the characteristic biochemical properties of Ddh in a unicellular cyanobacterium, which are different from those of other bacterial Ddhs.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Masahiro Takeya
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan.
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46
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Singh AK, Mallick N. Advances in cyanobacterial polyhydroxyalkanoates production. FEMS Microbiol Lett 2017; 364:4107776. [DOI: 10.1093/femsle/fnx189] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 09/06/2017] [Indexed: 12/25/2022] Open
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47
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Yasuda C, Iijima H, Sukigara H, Osanai T. Incubation of Cyanobacteria under Dark, Anaerobic Conditions and Quantification of the Excreted Organic Acids by HPLC. Bio Protoc 2017; 7:e2257. [PMID: 34541244 DOI: 10.21769/bioprotoc.2257] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/21/2017] [Accepted: 03/26/2017] [Indexed: 11/02/2022] Open
Abstract
Succinate and lactate are commodity chemicals used for producing bioplastics. Recently, it was found that such organic acids are excreted from cells of the unicellular cyanobacterium Synechocystis sp. PCC 6803 under dark, anaerobic conditions. To conduct the dark, anaerobic incubation, cells were concentrated within a vial that was then sealed with a butyl rubber cap, following which N2 gas was introduced into the vial. The organic acids produced were quantified by high-performance liquid chromatography via post-labeling with bromothymol blue as a pH indicator. After separation by ion-exclusion chromatography, the organic acids were identified by comparing their retention time with that of standard solutions. These procedures allow researchers to quantify the organic acids produced by microorganisms, contributing to knowledge about the biology and biotechnology of cyanobacteria.
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Affiliation(s)
- Chika Yasuda
- School of Agriculture, Meiji University, Kanagawa, Japan
| | - Hiroko Iijima
- School of Agriculture, Meiji University, Kanagawa, Japan
| | | | - Takashi Osanai
- School of Agriculture, Meiji University, Kanagawa, Japan
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48
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Tomita Y, Yoshioka K, Iijima H, Nakashima A, Iwata O, Suzuki K, Hasunuma T, Kondo A, Hirai MY, Osanai T. Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions. Front Microbiol 2016; 7:2050. [PMID: 28066371 PMCID: PMC5174102 DOI: 10.3389/fmicb.2016.02050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/07/2016] [Indexed: 01/01/2023] Open
Abstract
Euglena gracilis is a eukaryotic, unicellular phytoflagellate that has been widely studied in basic science and applied science. Under dark, anaerobic conditions, the cells of E. gracilis produce a wax ester that can be converted into biofuel. Here, we demonstrate that under dark, anaerobic conditions, E. gracilis excretes organic acids, such as succinate and lactate, which are bulk chemicals used in the production of bioplastics. The levels of succinate were altered by changes in the medium and temperature during dark, anaerobic incubation. Succinate production was enhanced when cells were incubated in CM medium in the presence of NaHCO3. Excretion of lactate was minimal in the absence of external carbon sources, but lactate was produced in the presence of glucose during dark, anaerobic incubation. E. gracilis predominantly produced L-lactate; however, the percentage of D-lactate increased to 28.4% in CM medium at 30°C. Finally, we used a commercial strain of E. gracilis for succinate production and found that nitrogen-starved cells, incubated under dark, anaerobic conditions, produced 869.6 mg/L succinate over a 3-day incubation period, which was 70-fold higher than the amount produced by nitrogen-replete cells. This is the first study to demonstrate organic acid excretion by E. gracilis cells and to reveal novel aspects of primary carbon metabolism in this organism.
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Affiliation(s)
- Yuko Tomita
- School of Agriculture, Meiji University Kawasaki, Japan
| | | | - Hiroko Iijima
- School of Agriculture, Meiji University Kawasaki, Japan
| | | | | | | | - Tomohisa Hasunuma
- Graduate School of Science, Technology and Innovation, Kobe University Kobe, Japan
| | - Akihiko Kondo
- Graduate School of Science, Technology and Innovation, Kobe University Kobe, Japan
| | | | - Takashi Osanai
- School of Agriculture, Meiji UniversityKawasaki, Japan; RIKEN Center for Sustainable Resource ScienceYokohama, Japan
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49
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Metabolic engineering of cyanobacteria for the photosynthetic production of succinate. Metab Eng 2016; 38:483-493. [PMID: 27989804 DOI: 10.1016/j.ymben.2016.10.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/07/2016] [Accepted: 10/25/2016] [Indexed: 10/20/2022]
Abstract
Succinate is an important commodity chemical currently used in the food, pharmaceutical, and polymer industries. It can also be chemically converted into other major industrial chemicals such as 1,4-butanediol, butadiene, and tetrahydrofuran. Here we metabolically engineered a model cyanobacterium Synechococcus elongatus PCC 7942 to photosynthetically produce succinate. We expressed the genes encoding for α-ketoglutarate decarboxylase and succinate semialdehyde dehydrogenase in S. elongatus PCC 7942, resulting in a strain capable of producing 120mg/L of succinate. However, this recombinant strain exhibited severe growth retardation upon induction of the genes encoding for the succinate producing pathway, potentially due to the depletion of α-ketoglutarate. To replenish α-ketoglutarate, we expressed the genes encoding for phosphoenolpyruvate carboxylase and citrate synthase from Corynebacterium glutamicum into the succinate producing strain. The resulting strain successfully restored the growth phenotype and produced succinate with a titer of 430mg/L in 8 days. These results demonstrated the possibility of photoautotrophic succinate production.
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50
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Iijima H, Shirai T, Okamoto M, Pinto F, Tamagnini P, Hasunuma T, Kondo A, Hirai MY, Osanai T. Metabolomics-based analysis revealing the alteration of primary carbon metabolism by the genetic manipulation of a hydrogenase HoxH in Synechocystis sp. PCC 6803. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.06.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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