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Kosourov S, Böhm M, Senger M, Berggren G, Stensjö K, Mamedov F, Lindblad P, Allahverdiyeva Y. Photosynthetic hydrogen production: Novel protocols, promising engineering approaches and application of semi-synthetic hydrogenases. PHYSIOLOGIA PLANTARUM 2021; 173:555-567. [PMID: 33860946 DOI: 10.1111/ppl.13428] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
Photosynthetic production of molecular hydrogen (H2 ) by cyanobacteria and green algae is a potential source of renewable energy. These organisms are capable of water biophotolysis by taking advantage of photosynthetic apparatus that links water oxidation at Photosystem II and reduction of protons to H2 downstream of Photosystem I. Although the process has a theoretical potential to displace fossil fuels, photosynthetic H2 production in its current state is not yet efficient enough for industrial applications due to a number of physiological, biochemical, and engineering barriers. This article presents a short overview of the metabolic pathways and enzymes involved in H2 photoproduction in cyanobacteria and green algae and our present understanding of the mechanisms of this process. We also summarize recent advances in engineering photosynthetic cell factories capable of overcoming the major barriers to efficient and sustainable H2 production.
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Affiliation(s)
- Sergey Kosourov
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, Finland
| | - Maximilian Böhm
- Molecular Biomimetics, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Moritz Senger
- Molecular Biomimetics, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Gustav Berggren
- Molecular Biomimetics, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Karin Stensjö
- Microbial Chemistry, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Fikret Mamedov
- Molecular Biomimetics, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Yagut Allahverdiyeva
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, Finland
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Glucosidase Inhibitors Screening in Microalgae and Cyanobacteria Isolated from the Amazon and Proteomic Analysis of Inhibitor Producing Synechococcus sp. GFB01. Microorganisms 2021; 9:microorganisms9081593. [PMID: 34442672 PMCID: PMC8402191 DOI: 10.3390/microorganisms9081593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 11/17/2022] Open
Abstract
Microalgae and cyanobacteria are good sources for prospecting metabolites of biotechnological interest, including glucosidase inhibitors. These inhibitors act on enzymes related to various biochemical processes; they are involved in metabolic diseases, such as diabetes and Gaucher disease, tumors and viral infections, thus, they are interesting hubs for the development of new drugs and therapies. In this work, the screening of 63 environmental samples collected in the Brazilian Amazon found activity against β-glucosidase, of at least 60 min, in 13.85% of the tested extracts, with Synechococcus sp. GFB01 showing inhibitory activity of 90.2% for α-glucosidase and 96.9% against β-glucosidase. It was found that the nutritional limitation due to a reduction in the concentration of sodium nitrate, despite not being sufficient to cause changes in cell growth and photosynthetic apparatus, resulted in reduced production of α and β-glucosidase inhibitors and differential protein expression. The proteomic analysis of cyanobacteria isolated from the Amazon is unprecedented, with this being the first work to evaluate the protein expression of Synechococcus sp. GFB01 subjected to nutritional stress. This evaluation helps to better understand the metabolic responses of this organism, especially related to the production of inhibitors, adding knowledge to the industrial potential of these cyanobacterial compounds.
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Wang S, Xiao J, Wan L, Zhou Z, Wang Z, Song C, Zhou Y, Cao X. Mutual Dependence of Nitrogen and Phosphorus as Key Nutrient Elements: One Facilitates Dolichospermum flos-aquae to Overcome the Limitations of the Other. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5653-5661. [PMID: 29688011 DOI: 10.1021/acs.est.7b04992] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dolichospermum flos-aquae (formerly Anabaena flos-aquae) is a diazotrophic cyanobacterium causing harmful blooms worldwide, which is partly attributed to its capacity to compete for nitrogen (N) and phosphorus (P). Preventing the blooms by reducing P alone or both N and P has caused debate. To test the effects alone and together on the growth of cyanobacteria, we performed culture experiments in different eutrophication scenarios. N2 fixation in terms of heterocyst density, nitrogenase activity and nifH expression increased significantly in P-replete cultures, suggesting that P enrichment facilitates N2 fixation. Correspondingly, the expression of genes involved in P uptake, e.g., those involved in P-transport ( pstS) and the hydrolysis of phosphomonoesters ( phoD), was upregulated in P-deficient cultures. Interestingly, N addition enhanced not only the expression of these genes but also polyphosphate formation and alkaline phosphatase activity in P-deficient cultures relative to the P-replete cultures, as evidenced by qualitative (enzyme-labeled fluorescence) and quantitative (fluorogenic spectrophotometry) measurements. Furthermore, after N addition, cell activity and growth increased in the P-deficient cultures, underscoring the risk of N enrichment in P-limited systems. The eco-physiological responses shown here help further our understanding of the mechanism of N and P colimitation and underscore the importance of dual N and P reduction in controlling cyanobacterial blooms.
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Affiliation(s)
- Siyang Wang
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Jian Xiao
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Lingling Wan
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Zijun Zhou
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Zhicong Wang
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Chunlei Song
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Yiyong Zhou
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
| | - Xiuyun Cao
- Key Laboratory of Algal Biology, State Key Laboratory of Freshwater Ecology and Biotechnology , Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Science , Donghu South Road , Wuhan , 430072 China
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Dinitrogenase-Driven Photobiological Hydrogen Production Combats Oxidative Stress in Cyanothece sp. Strain ATCC 51142. Appl Environ Microbiol 2016; 82:7227-7235. [PMID: 27742679 DOI: 10.1128/aem.02098-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/30/2016] [Indexed: 01/21/2023] Open
Abstract
Photobiologically synthesized hydrogen (H2) gas is carbon neutral to produce and clean to combust, making it an ideal biofuel. Cyanothece sp. strain ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2 production, a highly perplexing phenomenon because H2 evolving enzymes are O2 sensitive. We employed a system-level in vivo chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity. We found that NifHDK responds to intracellular redox conditions and may act as an emergency electron valve to prevent harmful reactive oxygen species formation in concert with other cell strategies for maintaining redox homeostasis. These results provide new insight into cellular redox dynamics useful for advancing photolytic bioenergy technology and reveal a new understanding for the biological function of NifHDK. IMPORTANCE Here, we demonstrate that high levels of hydrogen synthesis can be induced as a protection mechanism against oxidative stress via the dinitrogenase enzyme complex in Cyanothece sp. strain ATCC 51142. This is a previously unknown feature of cyanobacterial dinitrogenase, and we anticipate that it may represent a strategy to exploit cyanobacteria for efficient and scalable hydrogen production. We utilized a chemoproteomic approach to capture the in situ dynamics of reductant partitioning within the cell, revealing proteins and reactive thiols that may be involved in redox sensing and signaling. Additionally, this method is widely applicable across biological systems to achieve a greater understanding of how cells navigate their environment and how redox chemistry can be utilized to alter metabolism and achieve homeostasis.
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Bernstein HC, Charania MA, McClure RS, Sadler NC, Melnicki MR, Hill EA, Markillie LM, Nicora CD, Wright AT, Romine MF, Beliaev AS. Multi-Omic Dynamics Associate Oxygenic Photosynthesis with Nitrogenase-Mediated H2 Production in Cyanothece sp. ATCC 51142. Sci Rep 2015; 5:16004. [PMID: 26525576 PMCID: PMC4630603 DOI: 10.1038/srep16004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/21/2015] [Indexed: 12/02/2022] Open
Abstract
To date, the proposed mechanisms of nitrogenase-driven photosynthetic H2 production by the diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142 have assumed that reductant and ATP requirements are derived solely from glycogen oxidation and cyclic-electron flow around photosystem I. Through genome-scale transcript and protein profiling, this study presents and tests a new hypothesis on the metabolic relationship between oxygenic photosynthesis and nitrogenase-mediated H2 production in Cyanothece 51142. Our results show that net-positive rates of oxygenic photosynthesis and increased expression of photosystem II reaction centers correspond and are synchronized with nitrogenase expression and H2 production. These findings provide a new and more complete view on the metabolic processes contributing to the energy budget of photosynthetic H2 production and highlight the role of concurrent photocatalytic H2O oxidation as a participating process.
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Affiliation(s)
- Hans C Bernstein
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, WA 99352.,Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Moiz A Charania
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Ryan S McClure
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Natalie C Sadler
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Matthew R Melnicki
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Eric A Hill
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Lye Meng Markillie
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Carrie D Nicora
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Aaron T Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Margaret F Romine
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
| | - Alexander S Beliaev
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA, 99352
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Immethun CM, Ng KM, DeLorenzo DM, Waldron-Feinstein B, Lee YC, Moon TS. Oxygen-responsive genetic circuits constructed in Synechocystis sp. PCC 6803. Biotechnol Bioeng 2015; 113:433-42. [PMID: 26264210 DOI: 10.1002/bit.25722] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/18/2015] [Accepted: 08/04/2015] [Indexed: 02/03/2023]
Abstract
As photoautotrophic prokaryotes, cyanobacteria are promising platforms for producing value-added bioproducts. However, few regulatory genetic parts and devices (e.g., inducible promoters and regulatory circuits) have been developed for these potential hosts. Furthermore, the devices that have been created respond only to a single input. To address these issues, we developed an inducible genetic circuit that generates heterologous proteins in response to oxygen, an environmental signal. To test its performance and utility in Synechocystis sp. PCC 6803, a model cyanobacterial strain, we connected this circuit to either heterologous nifHDK genes, which encode oxygen-sensitive nitrogenase's structural proteins, or a fluorescent protein gene. The circuit was transcriptionally activated to generate nifHDK transcripts or fluorescent output only in low oxygen conditions. We expanded the oxygen-responsive circuit into a more complex circuit by building a two-input AND gate, which allows Synechocystis to specifically control expression of the fluorescent reporter in response to two signals, low oxygen and high anhydrotetracycline. To our knowledge, the AND gate is the first complex logic circuit built in a cyanobacterial strain. This work expands the synthetic biology tools available for complex gene expression in cyanobacteria, increasing their potential as biotechnology platforms.
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Affiliation(s)
- Cheryl M Immethun
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Kenneth M Ng
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Drew M DeLorenzo
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Ben Waldron-Feinstein
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Ying-Chiang Lee
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Tae Seok Moon
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri.
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Dechatiwongse P, Maitland G, Hellgardt K. Demonstration of a two-stage aerobic/anaerobic chemostat for the enhanced production of hydrogen and biomass from unicellular nitrogen-fixing cyanobacterium. ALGAL RES 2015. [DOI: 10.1016/j.algal.2015.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Modelling of light and temperature influences on cyanobacterial growth and biohydrogen production. ALGAL RES 2015. [DOI: 10.1016/j.algal.2015.03.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rockwell NC, Martin SS, Gan F, Bryant DA, Lagarias JC. NpR3784 is the prototype for a distinctive group of red/green cyanobacteriochromes using alternative Phe residues for photoproduct tuning. Photochem Photobiol Sci 2015; 14:258-69. [DOI: 10.1039/c4pp00336e] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We report chromophore–protein interactions used by cyanobacteriochrome NpR3784 and related proteins for spectral tuning of the green-absorbing photoproduct state. These interactions are distinct from those used by canonical red/green cyanobacteriochromes.
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Affiliation(s)
- Nathan C. Rockwell
- Department of Molecular and Cell Biology
- University of California at Davis
- Davis
- USA
| | - Shelley S. Martin
- Department of Molecular and Cell Biology
- University of California at Davis
- Davis
- USA
| | - Fei Gan
- Department of Biochemistry and Molecular Biology
- The Pennsylvania State University
- University Park
- USA
| | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology
- The Pennsylvania State University
- University Park
- USA
- Department of Chemistry and Biochemistry
| | - J. Clark Lagarias
- Department of Molecular and Cell Biology
- University of California at Davis
- Davis
- USA
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10
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Welkie D, Zhang X, Markillie ML, Taylor R, Orr G, Jacobs J, Bhide K, Thimmapuram J, Gritsenko M, Mitchell H, Smith RD, Sherman LA. Transcriptomic and proteomic dynamics in the metabolism of a diazotrophic cyanobacterium, Cyanothece sp. PCC 7822 during a diurnal light-dark cycle. BMC Genomics 2014; 15:1185. [PMID: 25547186 PMCID: PMC4320622 DOI: 10.1186/1471-2164-15-1185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/16/2014] [Indexed: 12/26/2022] Open
Abstract
Background Cyanothece sp. PCC 7822 is an excellent cyanobacterial model organism with great potential to be applied as a biocatalyst for the production of high value compounds. Like other unicellular diazotrophic cyanobacterial species, it has a tightly regulated metabolism synchronized to the light–dark cycle. Utilizing transcriptomic and proteomic methods, we quantified the relationships between transcription and translation underlying central and secondary metabolism in response to nitrogen free, 12 hour light and 12 hour dark conditions. Results By combining mass-spectrometry based proteomics and RNA-sequencing transcriptomics, we quantitatively measured a total of 6766 mRNAs and 1322 proteins at four time points across a 24 hour light–dark cycle. Photosynthesis, nitrogen fixation, and carbon storage relevant genes were expressed during the preceding light or dark period, concurrent with measured nitrogenase activity in the late light period. We describe many instances of disparity in peak mRNA and protein abundances, and strong correlation of light dependent expression of both antisense and CRISPR-related gene expression. The proteins for nitrogenase and the pentose phosphate pathway were highest in the dark, whereas those for glycolysis and the TCA cycle were more prominent in the light. Interestingly, one copy of the psbA gene encoding the photosystem II (PSII) reaction center protein D1 (psbA4) was highly upregulated only in the dark. This protein likely cannot catalyze O2 evolution and so may be used by the cell to keep PSII intact during N2 fixation. The CRISPR elements were found exclusively at the ends of the large plasmid and we speculate that their presence is crucial to the maintenance of this plasmid. Conclusions This investigation of parallel transcriptional and translational activity within Cyanothece sp. PCC 7822 provided quantitative information on expression levels of metabolic pathways relevant to engineering efforts. The identification of expression patterns for both mRNA and protein affords a basis for improving biofuel production in this strain and for further genetic manipulations. Expression analysis of the genes encoded on the 6 plasmids provided insight into the possible acquisition and maintenance of some of these extra-chromosomal elements. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1185) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Louis A Sherman
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.
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Aryal UK, Callister SJ, McMahon BH, McCue LA, Brown J, Stöckel J, Liberton M, Mishra S, Zhang X, Nicora CD, Angel TE, Koppenaal DW, Smith RD, Pakrasi HB, Sherman LA. Proteomic Profiles of Five Strains of Oxygenic Photosynthetic Cyanobacteria of the Genus Cyanothece. J Proteome Res 2014; 13:3262-76. [DOI: 10.1021/pr5000889] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Uma K. Aryal
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Stephen J. Callister
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | | | - Lee-Ann McCue
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Joseph Brown
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Jana Stöckel
- Department
of Biology, Washington University, St. Louis, Missouri 63130, United States
- MOgene Green Chemicals LC, St. Louis, Missouri 63132, United States
| | - Michelle Liberton
- Department
of Biology, Washington University, St. Louis, Missouri 63130, United States
| | - Sujata Mishra
- Department
of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Xiaohui Zhang
- Department
of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Carrie D. Nicora
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Thomas E. Angel
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Kinemed, Inc., Horton Street, Emeryville, California 94608, United States
| | - David W. Koppenaal
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Richard D. Smith
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Himadri B. Pakrasi
- Department
of Biology, Washington University, St. Louis, Missouri 63130, United States
| | - Louis A. Sherman
- Department
of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
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Welkie DG, Sherman DM, Chrisler WB, Orr G, Sherman LA. Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822. PHOTOSYNTHESIS RESEARCH 2013; 118:25-36. [PMID: 24142038 DOI: 10.1007/s11120-013-9941-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 10/02/2013] [Indexed: 06/02/2023]
Abstract
The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H2 production when grown under 12 h light-12 h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K2HPO4 concentrations from 17.6 and 0.23 to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.
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Affiliation(s)
- David G Welkie
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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13
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Alagesan S, Gaudana SB, Sinha A, Wangikar PP. Metabolic flux analysis of Cyanothece sp. ATCC 51142 under mixotrophic conditions. PHOTOSYNTHESIS RESEARCH 2013; 118:191-198. [PMID: 23954952 DOI: 10.1007/s11120-013-9911-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/06/2013] [Indexed: 06/02/2023]
Abstract
Cyanobacteria are a group of photosynthetic prokaryotes capable of utilizing solar energy to fix atmospheric carbon dioxide to biomass. Despite several "proof of principle" studies, low product yield is an impediment in commercialization of cyanobacteria-derived biofuels. Estimation of intracellular reaction rates by (13)C metabolic flux analysis ((13)C-MFA) would be a step toward enhancing biofuel yield via metabolic engineering. We report (13)C-MFA for Cyanothece sp. ATCC 51142, a unicellular nitrogen-fixing cyanobacterium, known for enhanced hydrogen yield under mixotrophic conditions. Rates of reactions in the central carbon metabolism under nitrogen-fixing and -non-fixing conditions were estimated by monitoring the competitive incorporation of (12)C and (13)C from unlabeled CO2 and uniformly labeled glycerol, respectively, into terminal metabolites such as amino acids. The observed labeling patterns suggest mixotrophic growth under both the conditions, with a larger fraction of unlabeled carbon in nitrate-sufficient cultures asserting a greater contribution of carbon fixation by photosynthesis and an anaplerotic pathway. Indeed, flux analysis complements the higher growth observed under nitrate-sufficient conditions. On the other hand, the flux through the oxidative pentose phosphate pathway and tricarboxylic acid cycle was greater in nitrate-deficient conditions, possibly to supply the precursors and reducing equivalents needed for nitrogen fixation. In addition, an enhanced flux through fructose-6-phosphate phosphoketolase possibly suggests the organism's preferred mode under nitrogen-fixing conditions. The (13)C-MFA results complement the reported predictions by flux balance analysis and provide quantitative insight into the organism's distinct metabolic features under nitrogen-fixing and -non-fixing conditions.
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Affiliation(s)
- Swathi Alagesan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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14
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Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142. Proc Natl Acad Sci U S A 2013; 110:13210-5. [PMID: 23878254 DOI: 10.1073/pnas.1301171110] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program. We report identification of a temperature-dependent ultradian metabolic rhythm that controls the alternating oxygenic and microoxic processes of Cyanothece sp. ATCC 51142 under continuous high irradiance and in high CO2 concentration. During the oxygenic photosynthesis phase, nitrate deficiency limited protein synthesis and CO2 assimilation was directed toward glycogen synthesis. The carbohydrate accumulation reduced overexcitation of the photosynthetic reactions until a respiration burst initiated a transition to microoxic N2 fixation. In contrast to the circadian clock, this ultradian period is strongly temperature-dependent: 17 h at 27 °C, which continuously decreased to 10 h at 39 °C. The cycle was expressed by an oscillatory modulation of net O2 evolution, CO2 uptake, pH, fluorescence emission, glycogen content, cell division, and culture optical density. The corresponding ultradian modulation was also observed in the transcription of nitrogenase-related nifB and nifH genes and in nitrogenase activities. We propose that the control by the newly identified metabolic cycle adds another rhythmic component to the circadian clock that reflects the true metabolic state depending on the actual temperature, irradiance, and CO2 availability.
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