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Chandrasekhar T, Reddy PCO, Swapna B, Veeranjaneya Reddy L, Anuprasanna V, Dakshayani L, Ramachandra Reddy P, Reddy MC. Algae: the game-changers in biohydrogen sector. Crit Rev Biotechnol 2024:1-21. [PMID: 39142834 DOI: 10.1080/07388551.2024.2387176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 04/01/2023] [Accepted: 04/17/2023] [Indexed: 08/16/2024]
Abstract
Biohydrogen (H2) is an efficient form of renewable energy generated from various biological organisms. Specifically, primitive plants such as algae which are photosynthetic organisms can produce several commercial products, including biofuels due to their simple form, short life span, efficient photosynthetic capacity, and ability to grow in non-potable water sources. But these algae are often neglected and considered waste. Several studies have revealed the importance and role of algal species in generating biofuels, especially biohydrogen. Considerable research has been conducted in order to understand hydrogen production from algal sources. This review emphasizes the photolysis of water-based hydrogen production in algae apart from the metabolites fermentation process. The influence of physico-chemical factors, including oxygen scavengers, nanoparticles, and hydrogenases, was highlighted in this review to enhance H2 production from algal species. Also, several algal species used for hydrogen production are summarized in detail. Overall, this review intends to summarize the developments in hydrogen production from algal species keeping in view of excellent prospects. This knowledge certainly would provide a good opportunity for the industrial production of hydrogen using algal species, which is one of the most concerned areas in the energy sector.
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Affiliation(s)
| | | | - Battana Swapna
- Department of Botany, Vikrama Simhapuri University College, Kavali, India
| | | | | | - Lomada Dakshayani
- Department of Genetics & Genomics, Yogi Vemana University, Kadapa, India
| | | | - Madhava C Reddy
- Department of Biotechnology & Bioinformatics, Yogi Vemana University, Kadapa, India
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2
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Li W, Yao Y, Qin H, Fan X, Zhang X, Liu M, Ma W. Synergistic enhancement of pulsed light-induced H 2 photoproduction in Chlamydomonas cells by optimal sulfite concentration and light waveform. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 257:112962. [PMID: 38917720 DOI: 10.1016/j.jphotobiol.2024.112962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 05/31/2024] [Accepted: 06/17/2024] [Indexed: 06/27/2024]
Abstract
Pulsed light illumination stands out as a noteworthy technique for photosynthetic H2 production, playing a crucial role in eliminating O2 and activating hydrogenase enzymes. However, further improvements are essential to make H2 photoproduction suitable for future commercial applications. In our study, we observed a distinct enhancement in pulsed light-induced H2 photoproduction in the unicellular green alga Chlamydomonas reinhardtii when treated with the optimal concentration of the mild O2 scavenger Na2SO3. This improvement was a result of reduced O2 content, increased hydrogenase enzyme activity, and suppressed H2-uptake activity. Furthermore, our findings indicate that exposing Na2SO3-treated C. reinhardtii to optimal light waveform continues to significantly boost pulsed light-induced H2 photoproduction, attributed to the alleviation of impaired photosystem II activity. Altogether, the combined application of optimal sulfite concentration and light waveform effectively enhances pulsed light-induced photosynthetic H2 production in the green alga C. reinhardtii.
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Affiliation(s)
- Wenqi Li
- Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; Zhongshan Fudan Joint Innovation Center, Zhongshan Industrial Technology Research Institute, 6 Xiangxing Road, Zhongshan 528403, China
| | - Ye Yao
- College of Life Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China
| | - Haokuan Qin
- Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; Zhongshan Fudan Joint Innovation Center, Zhongshan Industrial Technology Research Institute, 6 Xiangxing Road, Zhongshan 528403, China
| | - Xuewei Fan
- Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; Zhongshan Fudan Joint Innovation Center, Zhongshan Industrial Technology Research Institute, 6 Xiangxing Road, Zhongshan 528403, China
| | - Xiaolin Zhang
- Zhongshan Fudan Joint Innovation Center, Zhongshan Industrial Technology Research Institute, 6 Xiangxing Road, Zhongshan 528403, China; Institute for Electric Light Sources, Fudan University, 220 Handan Road, Shanghai 200433, China
| | - Muqing Liu
- Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; Zhongshan Fudan Joint Innovation Center, Zhongshan Industrial Technology Research Institute, 6 Xiangxing Road, Zhongshan 528403, China; Institute for Electric Light Sources, Fudan University, 220 Handan Road, Shanghai 200433, China.
| | - Weimin Ma
- College of Life Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China.
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Hippler M, Khosravitabar F. Light-Driven H 2 Production in Chlamydomonas reinhardtii: Lessons from Engineering of Photosynthesis. PLANTS (BASEL, SWITZERLAND) 2024; 13:2114. [PMID: 39124233 PMCID: PMC11314271 DOI: 10.3390/plants13152114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 07/22/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024]
Abstract
In the green alga Chlamydomonas reinhardtii, hydrogen production is catalyzed via the [FeFe]-hydrogenases HydA1 and HydA2. The electrons required for the catalysis are transferred from ferredoxin (FDX) towards the hydrogenases. In the light, ferredoxin receives its electrons from photosystem I (PSI) so that H2 production becomes a fully light-driven process. HydA1 and HydA2 are highly O2 sensitive; consequently, the formation of H2 occurs mainly under anoxic conditions. Yet, photo-H2 production is tightly coupled to the efficiency of photosynthetic electron transport and linked to the photosynthetic control via the Cyt b6f complex, the control of electron transfer at the level of photosystem II (PSII) and the structural remodeling of photosystem I (PSI). These processes also determine the efficiency of linear (LEF) and cyclic electron flow (CEF). The latter is competitive with H2 photoproduction. Additionally, the CBB cycle competes with H2 photoproduction. Consequently, an in-depth understanding of light-driven H2 production via photosynthetic electron transfer and its competition with CO2 fixation is essential for improving photo-H2 production. At the same time, the smart design of photo-H2 production schemes and photo-H2 bioreactors are challenges for efficient up-scaling of light-driven photo-H2 production.
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Affiliation(s)
- Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, 48143 Münster, Germany
- Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan
| | - Fatemeh Khosravitabar
- Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden
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4
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Kwok van der Giezen F, Honkanen S, Colas des Francs-Small C, Bond C, Small I. Applications of Synthetic Pentatricopeptide Repeat Proteins. PLANT & CELL PHYSIOLOGY 2024; 65:503-515. [PMID: 38035801 PMCID: PMC11094755 DOI: 10.1093/pcp/pcad150] [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: 07/31/2023] [Revised: 11/20/2023] [Accepted: 11/29/2023] [Indexed: 12/02/2023]
Abstract
RNA-binding proteins play integral roles in the regulation of essential processes in cells and as such are attractive targets for engineering to manipulate gene expression at the RNA level. Expression of transcripts in chloroplasts and mitochondria is heavily regulated by pentatricopeptide repeat (PPR) proteins. The diverse roles of PPR proteins and their naturally modular architecture make them ideal candidates for engineering. Synthetic PPR proteins are showing great potential to become valuable tools for controlling the expression of plastid and mitochondrial transcripts. In this review, by 'synthetic', we mean both rationally modified natural PPR proteins and completely novel proteins designed using the principles learned from their natural counterparts. We focus on the many different applications of synthetic PPR proteins, covering both their use in basic research to learn more about protein-RNA interactions and their use to achieve specific outcomes in RNA processing and the control of gene expression. We describe the challenges associated with the design, construction and deployment of synthetic PPR proteins and provide perspectives on how they might be assembled and used in future biotechnology applications.
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Affiliation(s)
- Farley Kwok van der Giezen
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Suvi Honkanen
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Catherine Colas des Francs-Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Charles Bond
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Ian Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
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5
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Chung KP, Loiacono FV, Neupert J, Wu M, Bock R. An RNA thermometer in the chloroplast genome of Chlamydomonas facilitates temperature-controlled gene expression. Nucleic Acids Res 2023; 51:11386-11400. [PMID: 37855670 PMCID: PMC10639063 DOI: 10.1093/nar/gkad816] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023] Open
Abstract
Riboregulators such as riboswitches and RNA thermometers provide simple, protein-independent tools to control gene expression at the post-transcriptional level. In bacteria, RNA thermometers regulate protein synthesis in response to temperature shifts. Thermometers outside of the bacterial world are rare, and in organellar genomes, no RNA thermometers have been identified to date. Here we report the discovery of an RNA thermometer in a chloroplast gene of the unicellular green alga Chlamydomonas reinhardtii. The thermometer, residing in the 5' untranslated region of the psaA messenger RNA forms a hairpin-type secondary structure that masks the Shine-Dalgarno sequence at 25°C. At 40°C, melting of the secondary structure increases accessibility of the Shine-Dalgarno sequence to initiating ribosomes, thus enhancing protein synthesis. By targeted nucleotide substitutions and transfer of the thermometer into Escherichia coli, we show that the secondary structure is necessary and sufficient to confer the thermometer properties. We also demonstrate that the thermometer provides a valuable tool for inducible transgene expression from the Chlamydomonas plastid genome, in that a simple temperature shift of the algal culture can greatly increase recombinant protein yields.
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Affiliation(s)
- Kin Pan Chung
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - F Vanessa Loiacono
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Juliane Neupert
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Mengting Wu
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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6
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Small I, Melonek J, Bohne AV, Nickelsen J, Schmitz-Linneweber C. Plant organellar RNA maturation. THE PLANT CELL 2023; 35:1727-1751. [PMID: 36807982 PMCID: PMC10226603 DOI: 10.1093/plcell/koad049] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/05/2023] [Accepted: 01/17/2023] [Indexed: 05/30/2023]
Abstract
Plant organellar RNA metabolism is run by a multitude of nucleus-encoded RNA-binding proteins (RBPs) that control RNA stability, processing, and degradation. In chloroplasts and mitochondria, these post-transcriptional processes are vital for the production of a small number of essential components of the photosynthetic and respiratory machinery-and consequently for organellar biogenesis and plant survival. Many organellar RBPs have been functionally assigned to individual steps in RNA maturation, often specific to selected transcripts. While the catalog of factors identified is ever-growing, our knowledge of how they achieve their functions mechanistically is far from complete. This review summarizes the current knowledge of plant organellar RNA metabolism taking an RBP-centric approach and focusing on mechanistic aspects of RBP functions and the kinetics of the processes they are involved in.
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Affiliation(s)
- Ian Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley 6009, Australia
| | - Joanna Melonek
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley 6009, Australia
| | | | - Jörg Nickelsen
- Department of Molecular Plant Sciences, LMU Munich, 82152 Martinsried, Germany
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Eloffy MG, Elgarahy AM, Saber AN, Hammad A, El-Sherif DM, Shehata M, Mohsen A, Elwakeel KZ. Biomass-to-sustainable biohydrogen: insights into the production routes, and technical challenges. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2022.100410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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8
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Ma K, Deng L, Wu H, Fan J. Towards green biomanufacturing of high-value recombinant proteins using promising cell factory: Chlamydomonas reinhardtii chloroplast. BIORESOUR BIOPROCESS 2022; 9:83. [PMID: 38647750 PMCID: PMC10992328 DOI: 10.1186/s40643-022-00568-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/29/2022] [Indexed: 11/10/2022] Open
Abstract
Microalgae are cosmopolitan organisms in nature with short life cycles, playing a tremendous role in reducing the pressure of industrial carbon emissions. Besides, microalgae have the unique advantages of being photoautotrophic and harboring both prokaryotic and eukaryotic expression systems, becoming a popular host for recombinant proteins. Currently, numerous advanced molecular tools related to microalgal transgenesis have been explored and established, especially for the model species Chlamydomonas reinhardtii (C. reinhardtii hereafter). The development of genetic tools and the emergence of new strategies further increase the feasibility of developing C. reinhardtii chloroplasts as green factories, and the strong genetic operability of C. reinhardtii endows it with enormous potential as a synthetic biology platform. At present, C. reinhardtii chloroplasts could successfully produce plenty of recombinant proteins, including antigens, antibodies, antimicrobial peptides, protein hormones and enzymes. However, additional techniques and toolkits for chloroplasts need to be developed to achieve efficient and markerless editing of plastid genomes. Mining novel genetic elements and selectable markers will be more intensively studied in the future, and more factors affecting protein expression are urged to be explored. This review focuses on the latest technological progress of selectable markers for Chlamydomonas chloroplast genetic engineering and the factors that affect the efficiency of chloroplast protein expression. Furthermore, urgent challenges and prospects for future development are pointed out.
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Affiliation(s)
- Ke Ma
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Lei Deng
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Haizhen Wu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
- Department of Applied Biology, East China University of Science and Technology, Shanghai, 200237, People's Republic of China.
| | - Jianhua Fan
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
- Department of Applied Biology, East China University of Science and Technology, Shanghai, 200237, People's Republic of China.
- School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832003, People's Republic of China.
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9
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Overcoming Poor Transgene Expression in the Wild-Type Chlamydomonas Chloroplast: Creation of Highly Mosquitocidal Strains of Chlamydomonas reinhardtii. Microorganisms 2022; 10:microorganisms10061087. [PMID: 35744605 PMCID: PMC9229432 DOI: 10.3390/microorganisms10061087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/19/2022] [Accepted: 05/21/2022] [Indexed: 12/10/2022] Open
Abstract
High-level expression of transgenes in the chloroplast of wild-type Chlamydomonas reinhardtii (C. reinhardtii) remains challenging for many genes (e.g., the cry toxin genes from Bacillus thuringiensis israelensis). The bottleneck is presumed to be post-transcriptional and mediated by the 5′ element and the coding region. Using 5′ elements from highly expressed photosynthesis genes such as atpA did not improve the outcome with cry11A regardless of the promoter. However, when we employed the 5′ UTR from mature rps4 mRNA with clean fusions to promoters, production of the rCry11A protein became largely promoter-dependent. The best results were obtained with the native 16S rrn promoter (−91 to −1). When it was fused to the mature 5′ rps4 UTR, rCry11A protein levels were ~50% higher than was obtained with the inducible system, or ~0.6% of total protein. This level was sufficient to visualize the 73-kDa rCry11A protein on Coomassie-stained gels of total algal protein. In addition, analysis of the expression of these transgenes by RT-PCR indicated that RNA levels roughly correlated with protein production. Live cell bioassays using the best strains as food for 3rd instar Aedes aegypti larvae showed that most larvae were killed even when the cell concentration was as low as 2 × 104 cells/mL. Finally, the results indicate that these highly toxic strains are also quite stable, and thus represent a key milestone in using C. reinhardtii for mosquito control.
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10
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Singh M, Mal N, Mohapatra R, Bagchi T, Parambath SD, Chavali M, Rao KM, Ramanaiah SV, Kadier A, Kumar G, Chandrasekhar K, Kim SH. Recent biotechnological developments in reshaping the microalgal genome: A signal for green recovery in biorefinery practices. CHEMOSPHERE 2022; 293:133513. [PMID: 34990720 DOI: 10.1016/j.chemosphere.2022.133513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 12/13/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
The use of renewable energy sources as a substitute for nonrenewable fossil fuels is urgently required. Algae biorefinery platform provides an excellent alternate to overcome future energy problems. However, to let this viable biomass be competent with existing feedstocks, it is necessary to exploit genetic manipulation and improvement in upstream and downstream platforms for optimal bio-product recovery. Furthermore, the techno-economic strategies further maximize metabolites production for biofuel, biohydrogen, and other industrial applications. The experimental methodologies in algal photobioreactor promote high biomass production, enriched in lipid and starch content in limited environmental conditions. This review presents an optimization framework combining genetic manipulation methods to simulate microalgal growth dynamics, understand the complexity of algal biorefinery to scale up, and identify green strategies for techno-economic feasibility of algae for biomass conversion. Overall, the algal biorefinery opens up new possibilities for the valorization of algae biomass and the synthesis of various novel products.
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Affiliation(s)
- Meenakshi Singh
- Department of Botany, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, 390002, Gujarat, India
| | - Navonil Mal
- Department of Botany, University of Calcutta, Kolkata, 700019, West Bengal, India
| | - Reecha Mohapatra
- Department of Life Sciences, NIT Rourkela, 769008, Odisha, India
| | - Trisha Bagchi
- Department of Botany, West Bengal State University, Barasat, 700126, West Bengal, India
| | | | - Murthy Chavali
- Office of the Dean (Research) & Division of Chemistry, Department of Science, Faculty of Science & Technology, Alliance University (Central Campus), Chandapura-Anekal Main Road, Bengaluru, 562106, Karnataka, India; NTRC-MCETRC and 109 Nano Composite Technologies Pvt. Ltd., Guntur District, 522201, Andhra Pradesh, India
| | - Kummara Madhusudana Rao
- School of Chemical Engineering, Yeungnam University, 280 Daehak-ro, Joyeong-dong, Gyeongsan-si, Gyeongsangbuk-do, 38541, South Korea; Department of Automotive Lighting Convergence Engineering, Yeungnam University, 280 Daehak-ro, Joyeong-dong, Gyeongsan-si, Gyeongsangbuk-do, 38541, South Korea
| | - S V Ramanaiah
- Food and Biotechnology Research Lab, South Ural State University (National Research University), 454080, Chelyabinsk, Russian Federation
| | - Abudukeremu Kadier
- Laboratory of Environmental Science and Technology, The Xinjiang Technical Institute of Physics and Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, 830011, China; Center of Material and Opto-electronic Research, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Gopalakrishnan Kumar
- Institute of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, 4036, Stavanger, Norway
| | - K Chandrasekhar
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Republic of Korea.
| | - Sang-Hyoun Kim
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Republic of Korea.
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11
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Bock R. Transplastomic approaches for metabolic engineering. CURRENT OPINION IN PLANT BIOLOGY 2022; 66:102185. [PMID: 35183927 DOI: 10.1016/j.pbi.2022.102185] [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: 10/18/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
The plastid (chloroplast) genome of seed plants represents an attractive target of metabolic pathway engineering by genetic transformation. Although the plastid genome is relatively small, it can accommodate large amounts of foreign DNA that precisely integrates via homologous recombination, and is largely excluded from pollen transmission due to the maternal mode of plastid inheritance. Since the engineering of metabolic pathways often requires the expression of multiple transgenes, the possibility to conveniently stack transgenes in synthetic operons makes the transplastomic technology particularly appealing in the area of metabolic engineering. Absence of epigenetic gene silencing mechanisms from plastids and the possibility to achieve high transgene expression levels further add to the attractiveness of plastid genome transformation. This review focuses on engineering principles and available tools for the transplastomic expression of enzymes and pathways, and highlights selected recent applications in metabolic engineering.
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Affiliation(s)
- Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany.
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12
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Cutolo EA, Mandalà G, Dall’Osto L, Bassi R. Harnessing the Algal Chloroplast for Heterologous Protein Production. Microorganisms 2022; 10:743. [PMID: 35456794 PMCID: PMC9025058 DOI: 10.3390/microorganisms10040743] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/24/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
Photosynthetic microbes are gaining increasing attention as heterologous hosts for the light-driven, low-cost production of high-value recombinant proteins. Recent advances in the manipulation of unicellular algal genomes offer the opportunity to establish engineered strains as safe and viable alternatives to conventional heterotrophic expression systems, including for their use in the feed, food, and biopharmaceutical industries. Due to the relatively small size of their genomes, algal chloroplasts are excellent targets for synthetic biology approaches, and are convenient subcellular sites for the compartmentalized accumulation and storage of products. Different classes of recombinant proteins, including enzymes and peptides with therapeutical applications, have been successfully expressed in the plastid of the model organism Chlamydomonas reinhardtii, and of a few other species, highlighting the emerging potential of transplastomic algal biotechnology. In this review, we provide a unified view on the state-of-the-art tools that are available to introduce protein-encoding transgenes in microalgal plastids, and discuss the main (bio)technological bottlenecks that still need to be addressed to develop robust and sustainable green cell biofactories.
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Affiliation(s)
| | | | | | - Roberto Bassi
- Laboratory of Photosynthesis and Bioenergy, Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy; (E.A.C.); (G.M.); (L.D.)
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13
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King SJ, Jerkovic A, Brown LJ, Petroll K, Willows RD. Synthetic biology for improved hydrogen production in Chlamydomonas reinhardtii. Microb Biotechnol 2022; 15:1946-1965. [PMID: 35338590 PMCID: PMC9249334 DOI: 10.1111/1751-7915.14024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 02/09/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
Hydrogen is a clean alternative to fossil fuels. It has applications for electricity generation and transportation and is used for the manufacturing of ammonia and steel. However, today, H2 is almost exclusively produced from coal and natural gas. As such, methods to produce H2 that do not use fossil fuels need to be developed and adopted. The biological manufacturing of H2 may be one promising solution as this process is clean and renewable. Hydrogen is produced biologically via enzymes called hydrogenases. There are three classes of hydrogenases namely [FeFe], [NiFe] and [Fe] hydrogenases. The [FeFe] hydrogenase HydA1 from the model unicellular algae Chlamydomonas reinhardtii has been studied extensively and belongs to the A1 subclass of [FeFe] hydrogenases that have the highest turnover frequencies amongst hydrogenases (21,000 ± 12,000 H2 s−1 for CaHydA from Clostridium acetobutyliticum). Yet to date, limitations in C. reinhardtii H2 production pathways have hampered commercial scale implementation, in part due to O2 sensitivity of hydrogenases and competing metabolic pathways, resulting in low H2 production efficiency. Here, we describe key processes in the biogenesis of HydA1 and H2 production pathways in C. reinhardtii. We also summarize recent advancements of algal H2 production using synthetic biology and describe valuable tools such as high‐throughput screening (HTS) assays to accelerate the process of engineering algae for commercial biological H2 production.
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Affiliation(s)
- Samuel J King
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ante Jerkovic
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Kerstin Petroll
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Robert D Willows
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
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14
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Shahar N, Elman T, Williams-Carrier R, Ben-Zvi O, Yacoby I, Barkan A. Use of plant chloroplast RNA-binding proteins as orthogonal activators of chloroplast transgenes in the green alga Chlamydomonas reinhardtii. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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15
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Rochaix JD, Surzycki R, Ramundo S. Regulated Chloroplast Gene Expression in Chlamydomonas. Methods Mol Biol 2021; 2317:305-318. [PMID: 34028778 DOI: 10.1007/978-1-0716-1472-3_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
The green unicellular alga Chlamydomonas reinhardtii has emerged as a very attractive model system for chloroplast genetic engineering. Algae can be transformed readily at the chloroplast level through bombardment of cells with a gene gun and transformants can be selected using antibiotic resistance or phototrophic growth. An inducible chloroplast gene expression system could be very useful for several reasons. First, it could be used to elucidate the function of essential chloroplast genes required for cell growth and survival. Second, it could be very helpful for expressing proteins which are toxic to the algal cells. Third, it would allow for the reversible depletion of photosynthetic complexes, thus making it possible to study their biogenesis in a controlled fashion. Fourth, it opens promising possibilities for hydrogen production in Chlamydomonas. Here we describe an inducible/ repressible chloroplast gene expression system in Chlamydomonas in which the copper-regulated Cyc6 promoter or the vitamin-controlled MetE promoter and TPP riboswitch drive the expression of the nuclear Nac2 gene encoding a protein which is targeted to the chloroplast where it acts specifically on the chloroplast psbD 5' untranslated region and is required for the stable accumulation of the psbD mRNA and photosystem II. The system can be used for any chloroplast gene or trans-gene by placing it under the control of the psbD 5'untranslated region.
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Affiliation(s)
- Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland.
| | | | - Silvia Ramundo
- School of Medicine, UC San Francisco, San Francisco, CA, USA
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16
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Jackson HO, Taunt HN, Mordaka PM, Smith AG, Purton S. The Algal Chloroplast as a Testbed for Synthetic Biology Designs Aimed at Radically Rewiring Plant Metabolism. FRONTIERS IN PLANT SCIENCE 2021; 12:708370. [PMID: 34630459 PMCID: PMC8497815 DOI: 10.3389/fpls.2021.708370] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/10/2021] [Indexed: 05/04/2023]
Abstract
Sustainable and economically viable support for an ever-increasing global population requires a paradigm shift in agricultural productivity, including the application of biotechnology to generate future crop plants. Current genetic engineering approaches aimed at enhancing the photosynthetic efficiency or composition of the harvested tissues involve relatively simple manipulations of endogenous metabolism. However, radical rewiring of central metabolism using new-to-nature pathways, so-called "synthetic metabolism", may be needed to really bring about significant step changes. In many cases, this will require re-programming the metabolism of the chloroplast, or other plastids in non-green tissues, through a combination of chloroplast and nuclear engineering. However, current technologies for sophisticated chloroplast engineering ("transplastomics") of plants are limited to just a handful of species. Moreover, the testing of metabolic rewiring in the chloroplast of plant models is often impractical given their obligate phototrophy, the extended time needed to create stable non-chimeric transplastomic lines, and the technical challenges associated with regeneration of whole plants. In contrast, the unicellular green alga, Chlamydomonas reinhardtii is a facultative heterotroph that allows for extensive modification of chloroplast function, including non-photosynthetic designs. Moreover, chloroplast engineering in C. reinhardtii is facile, with the ability to generate novel lines in a matter of weeks, and a well-defined molecular toolbox allows for rapid iterations of the "Design-Build-Test-Learn" (DBTL) cycle of modern synthetic biology approaches. The recent development of combinatorial DNA assembly pipelines for designing and building transgene clusters, simple methods for marker-free delivery of these clusters into the chloroplast genome, and the pre-existing wealth of knowledge regarding chloroplast gene expression and regulation in C. reinhardtii further adds to the versatility of transplastomics using this organism. Herein, we review the inherent advantages of the algal chloroplast as a simple and tractable testbed for metabolic engineering designs, which could then be implemented in higher plants.
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Affiliation(s)
- Harry O. Jackson
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Henry N. Taunt
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Pawel M. Mordaka
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Alison G. Smith
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Saul Purton
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
- *Correspondence: Saul Purton
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17
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Carrera-Pacheco SE, Hankamer B, Oey M. Light and heat-shock mediated TDA1 overexpression as a tool for controlled high-yield recombinant protein production in Chlamydomonas reinhardtii chloroplasts. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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18
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Wei L, Fan B, Yi J, Xie T, Liu K, Ma W. Mechanistic insights into pH-dependent H 2 photoproduction in bisulfite-treated Chlamydomonas cells. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:64. [PMID: 32280372 PMCID: PMC7132995 DOI: 10.1186/s13068-020-01704-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Bisulfite addition is an important H2 photoproduction strategy that removes O2 and activates hydrogenase. The pH values of cell cultures can change the ratio of bisulfite to sulfite, which may affect H2 photoproduction. However, little is known regarding the pH effect of bisulfite addition on H2 photoproduction and relevant underlying mechanism. RESULTS Here, changes in H2 photoproduction with different initial extracellular pH values showed a parabolic distribution and a pH of 8.0 is an optimal value for H2 photoproduction in Chlamydomonas reinhardtii cells treated with bisulfite. Compared to the growth pH (pH 7.3), increased photoproduction of H2 at this optimal pH was primarily caused by a relatively high residual activity of photosystem II (PSII), which provides a relatively plentiful source of electrons for H2 photoproduction. Such increased H2 photoproduction was most likely a result of decreased the ratio of bisulfite to sulfite, consistent with the result that the toxicity of bisulfite on PSII was much more than that of sulfite. This possibility was corroborated by the result that treatment with a combination of 7 mM bisulfite and 6 mM sulfite further enhanced H2 photoproduction compared with 13 mM bisulfite alone. CONCLUSIONS Collectively, our findings provide novel mechanistic insights into pH-dependent H2 photoproduction in C. reinhardtii cells treated with bisulfite, and demonstrate that sulfite addition is another important strategy for H2 photoproduction, just like bisulfite addition.
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Affiliation(s)
- Lanzhen Wei
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
| | - Baoqiang Fan
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
| | - Jing Yi
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
| | - Tianqun Xie
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
| | - Kun Liu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
| | - Weimin Ma
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China
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19
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Hsu SC, Browne DR, Tatli M, Devarenne TP, Stern DB. N-terminal sequences affect expression of triterpene biosynthesis enzymes in Chlamydomonas chloroplasts. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Tóth SZ, Yacoby I. Paradigm Shift in Algal H 2 Production: Bypassing Competitive Processes. Trends Biotechnol 2019; 37:1159-1163. [PMID: 31174881 DOI: 10.1016/j.tibtech.2019.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/29/2019] [Accepted: 05/03/2019] [Indexed: 12/26/2022]
Abstract
Hydrogen is a promising energy carrier, but producing it sustainably remains a challenge. Green algae can produce hydrogen photosynthetically using their efficient but oxygen-sensitive hydrogenases. Recent strategies aiming to bypass competing processes provide a promising route for scaling up algal hydrogen production.
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Affiliation(s)
- Szilvia Z Tóth
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726 Szeged, Hungary.
| | - Iftach Yacoby
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, 69978, Israel.
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Abstract
The current fossil fuel reserves are not sufficient to meet the increasing demand and very soon will become exhausted. Pollution, global warming, and inflated oil prices have led the quest for renewable energy sources. Algal biofuels represent a potential source of renewable energy. Algae, as the third generation feedstock, are suitable for biodiesel and bioethanol production due to their quick growth, excellent biomass yield, and high lipid and carbohydrate contents. With their huge potential, algae are expected to surpass the first and second generation feedstocks. Only a few thousand algal species have been investigated as possible biofuel sources, and none of them was ideal. This review summarizes the current status of algal biofuels, important steps of algal biofuel production, and the major commercial production challenges.
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22
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Boehm CR, Bock R. Recent Advances and Current Challenges in Synthetic Biology of the Plastid Genetic System and Metabolism. PLANT PHYSIOLOGY 2019; 179:794-802. [PMID: 30181342 PMCID: PMC6393795 DOI: 10.1104/pp.18.00767] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/27/2018] [Indexed: 05/05/2023]
Abstract
Building on recombinant DNA technology, leaps in synthesis, assembly, and analysis of DNA have revolutionized genetics and molecular biology over the past two decades (Kosuri and Church, 2014). These technological advances have accelerated the emergence of synthetic biology as a new discipline (Cameron et al., 2014). Synthetic biology is characterized by efforts targeted at the modification of existing and the design of novel biological systems based on principles adopted from information technology and engineering (Andrianantoandro et al., 2006; Khalil and Collins, 2010). As in more traditional engineering disciplines such as mechanical, electrical and civil engineering, synthetic biologists utilize abstraction, decoupling and standardization to make the design of biological systems more efficient and scalable. To facilitate the management of complexity, synthetic biology relies on an abstraction hierarchy composed of multiple levels (Endy, 2005): DNA as genetic material, "parts" as elements of DNA encoding basic biological functions (e.g. promoter, ribosome-binding site, terminator sequence), "devices" as any combination of parts implementing a human-defined function, and "systems" as any combination of devices fulfilling a predefined purpose. Parts are designated to perform predictable and modular functions in the context of higher-level devices or systems, which are successively refined through a cycle of designing, building, and testing.
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Affiliation(s)
- Christian R Boehm
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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23
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Barjona do Nascimento Coutinho P, Friedl C, Heilmann M, Buchholz R, Stute SC. Validated Nuclear-Based Transgene Expression Regulated by the Fea1 Iron-Responsive Promoter in the Green Alga Chlamydomonas reinhardtii. Mol Biotechnol 2019; 61:305-316. [DOI: 10.1007/s12033-018-00148-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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24
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Naghshbandi MP, Tabatabaei M, Aghbashlo M, Aftab MN, Iqbal I. Metabolic Engineering of Microalgae for Biofuel Production. Methods Mol Biol 2019; 1980:153-172. [PMID: 30666564 DOI: 10.1007/7651_2018_205] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Microalgae are considered as promising cell factories for the production of various types of biofuels, including bioethanol, biodiesel, and biohydrogen by using carbon dioxide and sunlight. In spite of unique advantages of these microorganisms, the commercialization of microalgal biofuels has been hindered by poor economic features. Metabolic engineering is among the most promising strategies put forth to overcome this challenge. In this chapter, metabolic pathways involved in lipid and hydrogen production by microalgae are reviewed and discussed. Moreover, metabolic and genetic engineering approaches investigated for improving the rate of lipid (as a feedstock for biodiesel production) and biohydrogen synthesis are presented. Finally, genetic engineering tools and approaches employed for engineering microalgal metabolic pathways are elaborated. A thorough step-by-step protocol for reconstructing the metabolic pathway of various microorganisms including microalgae is also presented.
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Affiliation(s)
- Mohammad Pooya Naghshbandi
- Department of Microbial Biotechnology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Meisam Tabatabaei
- Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Education, and Extension Organization (AREEO), Karaj, Iran. .,Biofuel Research Team (BRTeam), Karaj, Iran.
| | - Mortaza Aghbashlo
- Department of Mechanical Engineering of Agricultural Machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
| | - Muhammad Nauman Aftab
- Institute of Industrial Biotechnology, Government College University, Lahore, Pakistan
| | - Irfana Iqbal
- Department of Zoology, Lahore College for Women University, Lahore, Pakistan
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25
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Kwon YM, Kim KW, Choi TY, Kim SY, Kim JYH. Manipulation of the microalgal chloroplast by genetic engineering for biotechnological utilization as a green biofactory. World J Microbiol Biotechnol 2018; 34:183. [PMID: 30478596 DOI: 10.1007/s11274-018-2567-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022]
Abstract
The chloroplast is an essential organelle in microalgae for conducting photosynthesis, thus enabling the photoautotrophic growth of microalgae. In addition to photosynthesis, the chloroplast is capable of various biochemical processes for the synthesis of proteins, lipids, carbohydrates, and terpenoids. Due to these attractive characteristics, there has been increasing interest in the biotechnological utilization of microalgal chloroplast as a sustainable alternative to the conventional production platforms used in industrial biotechnology. Since the first demonstration of microalgal chloroplast transformation, significant development has occurred over recent decades in the manipulation of microalgal chloroplasts through genetic engineering. In the present review, we describe the advantages of the microalgal chloroplast as a production platform for various bioproducts, including recombinant proteins and high-value metabolites, features of chloroplast genetic systems, and the development of transformation methods, which represent important factors for gene expression in the chloroplast. Furthermore, we address the expression of various recombinant proteins in the microalgal chloroplast through genetic engineering, including reporters, biopharmaceutical proteins, and industrial enzymes. Finally, we present many efforts and achievements in the production of high-value metabolites in the microalgal chloroplast through metabolic engineering. Based on these efforts and advances, the microalgal chloroplast represents an economically viable and sustainable platform for biotechnological applications in the near future.
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Affiliation(s)
- Yong Min Kwon
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Kyung Woo Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Tae-Young Choi
- Department of Genetic Resources Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Sun Young Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Jaoon Young Hwan Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea.
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26
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Young R, Purton S. CITRIC: cold-inducible translational readthrough in the chloroplast of Chlamydomonas reinhardtii using a novel temperature-sensitive transfer RNA. Microb Cell Fact 2018; 17:186. [PMID: 30474564 PMCID: PMC6260665 DOI: 10.1186/s12934-018-1033-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/16/2018] [Indexed: 01/17/2023] Open
Abstract
Background The chloroplast of eukaryotic microalgae such as Chlamydomonas reinhardtii is a potential platform for metabolic engineering and the production of recombinant proteins. In industrial biotechnology, inducible expression is often used so that the translation or function of the heterologous protein does not interfere with biomass accumulation during the growth stage. However, the existing systems used in bacterial or fungal platforms do not transfer well to the microalgal chloroplast. We sought to develop a simple inducible expression system for the microalgal chloroplast, exploiting an unused stop codon (TGA) in the plastid genome. We have previously shown that this codon can be translated as tryptophan when we introduce into the chloroplast genome a trnWUCA gene encoding a plastidial transfer RNA with a modified anticodon sequence, UCA. Results A mutated version of our trnWUCA gene was developed that encodes a temperature-sensitive variant of the tRNA. This allows transgenes that have been modified to contain one or more internal TGA codons to be translated differentially according to the culture temperature, with a gradient of recombinant protein accumulation from 35 °C (low/off) to 15 °C (high). We have named this the CITRIC system, an acronym for cold-inducible translational readthrough in chloroplasts. The exact induction behaviour can be tailored by altering the number of TGA codons within the transgene. Conclusions CITRIC adds to the suite of genetic engineering tools available for the microalgal chloroplast, allowing a greater degree of control over the timing of heterologous protein expression. It could also be used as a heat-repressible system for studying the function of essential native genes in the chloroplast. The genetic components of CITRIC are entirely plastid-based, so no engineering of the nuclear genome is required. Electronic supplementary material The online version of this article (10.1186/s12934-018-1033-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rosanna Young
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.,Department of Medicine, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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27
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Wei L, Li X, Fan B, Ran Z, Ma W. A Stepwise NaHSO 3 Addition Mode Greatly Improves H 2 Photoproduction in Chlamydomonas reinhardtii. FRONTIERS IN PLANT SCIENCE 2018; 9:1532. [PMID: 30429859 PMCID: PMC6220153 DOI: 10.3389/fpls.2018.01532] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 09/28/2018] [Indexed: 05/23/2023]
Abstract
NaHSO3 addition greatly increases the yield of H2 photoproduction in a unicellular green alga Chlamydomonas reinhardtii through removing O2 and activating hydrogenase but significantly impairs the activity of PSII, an electron source for H2 photoproduction. Here, a stepwise addition mode of total 13 mM NaHSO3, an optimal concentration for H2 photoproduction of C. reinhardtii identified in a previous one step addition method, significantly improved H2 photoproduction. Such improvement was believed to be the result of increased residual PSII activity in an anaerobic background, but was at least independent of two alternative electron sinks for H2 photoproduction, cyclic electron transport around PSI and CO2 assimilation. Based on the above results, we propose that increased residual PSII activity in an anaerobic environment is an efficient strategy to enhance H2 photoproduction in C. reinhardtii, and the stepwise NaHSO3 addition mode is a case study in the strategy.
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28
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Kang S, Odom OW, Malone CL, Thangamani S, Herrin DL. Expression of a Synthetic Gene for the Major Cytotoxin (Cyt1Aa) of Bacillus thuringiensis subsp. israelensis in the Chloroplast of Wild-Type Chlamydomonas. BIOLOGY 2018; 7:biology7020029. [PMID: 29738473 PMCID: PMC6022862 DOI: 10.3390/biology7020029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 04/30/2018] [Accepted: 05/04/2018] [Indexed: 12/16/2022]
Abstract
Chlamydomonas reinhardtii (Chlamydomonas) strains that are toxic to mosquito larvae because they express chloroplast transgenes that are based on the mosquitocidal proteins of Bacillus thuringiensis subsp. israelensis (Bti) could be very useful in mosquito control. Chlamydomonas has several advantages for this approach, including genetic controls not generally available with industrial algae. The Bti toxin is produced by sporulating bacteria and has been used for mosquito control for >30 years without creating highly resistant mosquito populations. The suite of toxins is four main proteins: three Cry proteins and the cytotoxic Cyt1Aa (27 kDa). Cyt1Aa is not very toxic to mosquitoes by itself, but it prevents the development of resistance. The production of Cyt1Aa in other microbes, however, has been challenging due to its affinity for certain membrane phospholipids. Here we report on the production of recombinant Cyt1Aa (rCyt1A) in the chloroplast of photosynthetic Chlamydomonas at levels of at least 0.3% total protein. Live cell bioassays demonstrated toxicity of the rCyt1Aa Chlamydomonas to larvae of Aedes aegypti. We also expressed the chloroplast cyt1Aa gene in a wild-type Chlamydomonas strain (21 gr) that can grow on nitrate. These results have implications for developing a Chlamydomonas strain that will be toxic to mosquito larvae but will not induce strongly resistant populations.
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Affiliation(s)
| | - Obed W Odom
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
| | - Candice L Malone
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
| | - Saravanan Thangamani
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - David L Herrin
- Pond Life Technologies LLC, Cedar Park, TX 78613, USA.
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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29
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Li H, Liu Y, Wang Y, Chen M, Zhuang X, Wang C, Wang J, Hu Z. Improved photobio-H 2 production regulated by artificial miRNA targeting psbA in green microalga Chlamydomonas reinhardtii. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:36. [PMID: 29449884 PMCID: PMC5808451 DOI: 10.1186/s13068-018-1030-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/23/2018] [Indexed: 06/01/2023]
Abstract
BACKGROUND Sulfur-deprived cultivation of Chlamydomonas reinhardtii, referred as "two-stage culture" transferring the cells from regular algal medium to sulfur-deplete one, has been extensively studied to improve photobio-H2 production in this green microalga. During sulfur-deprivation treatment, the synthesis of a key component of photosystem II complex, D1 protein, was inhibited and improved photobio-H2 production could be established in C. reinhardtii. However, separation of algal cells from a regular liquid culture medium to a sulfur-deprived one is not only a discontinuous process, but also a cost- and time-consuming operation. More applicable and economic alternatives for sustained H2 production by C. reinhardtii are still highly required. RESULTS In the present study, a significant improvement in photobio-H2 production was observed in the transgenic green microalga C. reinhardtii, which employed a newly designed strategy based on a heat-inducible artificial miRNA (amiRNA) expression system targeting D1-encoded gene, psbA. A transgenic algal strain referred as "amiRNA-D1" has been successfully obtained by transforming the expression vector containing a heat-inducible promoter. After heat shock conducted in the same algal cultures, the expression of amiRNA-D1 was detected increased 15-fold accompanied with a 73% decrease of target gene psbA. More interestingly, this transgenic alga accumulated about 60% more H2 content than the wild-type strain CC-849 at the end of 7-day cultivation. CONCLUSIONS The photobio-H2 production in the engineered transgenic alga was significantly improved. Without imposing any nutrient-deprived stress, this novel strategy provided a convenient and efficient way for regulation of photobio-H2 production in green microalga by simply "turn on" the expression of a designed amiRNA.
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Affiliation(s)
- Hui Li
- Guangdong Technology Research Center for Marine Algal Bioengineering, Guangdong Key Laboratory of Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Yanmei Liu
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Yuting Wang
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Meirong Chen
- Guangdong Technology Research Center for Marine Algal Bioengineering, Guangdong Key Laboratory of Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Xiaoshan Zhuang
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Chaogang Wang
- Guangdong Technology Research Center for Marine Algal Bioengineering, Guangdong Key Laboratory of Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Jiangxin Wang
- Guangdong Technology Research Center for Marine Algal Bioengineering, Guangdong Key Laboratory of Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Zhangli Hu
- Guangdong Technology Research Center for Marine Algal Bioengineering, Guangdong Key Laboratory of Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
- Shenzhen Key Laboratory of Marine Bioresource & Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060 People’s Republic of China
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Lee S, Lee YJ, Choi S, Park SB, Tran QG, Heo J, Kim HS. Development of an alcohol-inducible gene expression system for recombinant protein expression in Chlamydomonas reinhardtii. JOURNAL OF APPLIED PHYCOLOGY 2018; 30:2297-2304. [PMID: 30147236 PMCID: PMC6096782 DOI: 10.1007/s10811-018-1480-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 04/12/2018] [Accepted: 04/12/2018] [Indexed: 05/13/2023]
Abstract
Microalgae have been widely considered for the production of valuable products, such as lipid-based biofuel, value-added pigments, and anti-photo aging reagents. More recently, microalgae have been considered an alternative host for recombinant protein production because of their economic benefits and ecofriendly characteristics. Additionally, many microalgal strains identified to date are generally recognized as safe (GRAS); therefore, the use of microalgae-based technology is promising. However, basic studies on the genetic engineering of microalgae are rare, despite their importance. Particularly, inducible promoter systems that can be applied for strain engineering or recombinant protein production are rarely studied; hence, a number of challenging issues remain unsolved. Therefore, in this study, we focused on the development of a convenient and compact-inducible promoter system that can be used in microalgae. Based on previous success with plant systems, we employed the alcohol-inducible AlcR-P alcA system, which originates from the filamentous fungus, Aspergillus nidulans. This system comprises only two components, a regulatory protein, AlcR, and an inducible promoter, P alcA. Therefore, construction and transformation of the gene cassettes can be easily performed. Ethanol-dependent gene expression was observed in the transformants with no significant growth retardation or inducer consumption observed in the cells cultivated under optimized conditions.
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Affiliation(s)
- Sujin Lee
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Department of Environmental Biotechnology, KRIBB school of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
| | - Yong Jae Lee
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
| | - Saehae Choi
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Present Address: K-Biohealth, Osong, Chungbuk, 28160 Republic of Korea
| | - Su-Bin Park
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Department of Environmental Biotechnology, KRIBB school of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
| | - Quynh-Giao Tran
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Department of Environmental Biotechnology, KRIBB school of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
| | - Jina Heo
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Department of Environmental Biotechnology, KRIBB school of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
| | - Hee-Sik Kim
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141 Republic of Korea
- Department of Environmental Biotechnology, KRIBB school of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113 Republic of Korea
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Nagy V, Podmaniczki A, Vidal-Meireles A, Tengölics R, Kovács L, Rákhely G, Scoma A, Tóth SZ. Water-splitting-based, sustainable and efficient H 2 production in green algae as achieved by substrate limitation of the Calvin-Benson-Bassham cycle. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:69. [PMID: 29560024 PMCID: PMC5858145 DOI: 10.1186/s13068-018-1069-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/07/2018] [Indexed: 05/08/2023]
Abstract
BACKGROUND Photobiological H2 production has the potential of becoming a carbon-free renewable energy source, because upon the combustion of H2, only water is produced. The [Fe-Fe]-type hydrogenases of green algae are highly active, although extremely O2-sensitive. Sulphur deprivation is a common way to induce H2 production, which, however, relies substantially on organic substrates and imposes a severe stress effect resulting in the degradation of the photosynthetic apparatus. RESULTS We report on the establishment of an alternative H2 production method by green algae that is based on a short anaerobic induction, keeping the Calvin-Benson-Bassham cycle inactive by substrate limitation and preserving hydrogenase activity by applying a simple catalyst to remove the evolved O2. Cultures remain photosynthetically active for several days, with the electrons feeding the hydrogenases mostly derived from water. The amount of H2 produced is higher as compared to the sulphur-deprivation procedure and the process is photoautotrophic. CONCLUSION Our protocol demonstrates that it is possible to sustainably use algal cells as whole-cell catalysts for H2 production, which enables industrial application of algal biohydrogen production.
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Affiliation(s)
- Valéria Nagy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - Anna Podmaniczki
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - André Vidal-Meireles
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - Roland Tengölics
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Közép fasor 52, 6726 Szeged, Hungary
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
| | - Alberto Scoma
- Center for Geomicrobiology, Aarhus University, Ny Munkegade 116, 8000 Aarhus, Denmark
| | - Szilvia Z. Tóth
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, 6726 Szeged, Hungary
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Evaluation of light energy to H 2 energy conversion efficiency in thin films of cyanobacteria and green alga under photoautotrophic conditions. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.09.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Bayro-Kaiser V, Nelson N. Microalgal hydrogen production: prospects of an essential technology for a clean and sustainable energy economy. PHOTOSYNTHESIS RESEARCH 2017; 133:49-62. [PMID: 28239761 PMCID: PMC5500669 DOI: 10.1007/s11120-017-0350-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/06/2017] [Indexed: 05/17/2023]
Abstract
Modern energy production is required to undergo a dramatic transformation. It will have to replace fossil fuel use by a sustainable and clean energy economy while meeting the growing world energy needs. This review analyzes the current energy sector, available energy sources, and energy conversion technologies. Solar energy is the only energy source with the potential to fully replace fossil fuels, and hydrogen is a crucial energy carrier for ensuring energy availability across the globe. The importance of photosynthetic hydrogen production for a solar-powered hydrogen economy is highlighted and the development and potential of this technology are discussed. Much successful research for improved photosynthetic hydrogen production under laboratory conditions has been reported, and attempts are underway to develop upscale systems. We suggest that a process of integrating these achievements into one system to strive for efficient sustainable energy conversion is already justified. Pursuing this goal may lead to a mature technology for industrial deployment.
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Affiliation(s)
- Vinzenz Bayro-Kaiser
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel.
| | - Nathan Nelson
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
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Proteomic approaches in microalgae: perspectives and applications. 3 Biotech 2017; 7:197. [PMID: 28667637 DOI: 10.1007/s13205-017-0831-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/19/2017] [Indexed: 12/13/2022] Open
Abstract
Biofuels are the promising sources which are produced by various microalgae or in the form of metabolic by-products from organic or food waste products. Microalgae have been widely reported for the production of biofuels since these have a high storage of lipids as triacylglycerides, which can mainly be converted into biofuels. Recently, products such as biodiesel, bioethanol and biogas have renewed the interest toward the microalgae. The proteomics alone will not pave the way toward finding an ideal alga which will fulfill the current energy demands, but a combined approach of proteomics, genomics and bioinformatics can be pivotal for a sustainable solution. The present review emphasizes various technologies currently involved in algal proteomics for the efficient production of biofuels.
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Kang S, Odom OW, Thangamani S, Herrin DL. Toward mosquito control with a green alga: Expression of Cry toxins of Bacillus thuringiensis subsp. israelensis (Bti) in the chloroplast of Chlamydomonas. JOURNAL OF APPLIED PHYCOLOGY 2017; 29:1377-1389. [PMID: 28713202 PMCID: PMC5509220 DOI: 10.1007/s10811-016-1008-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We are developing Chlamydomonas strains that can be used for safe and sustainable control of mosquitoes, because they produce proteins from Bacillus thuringiensis subsp. israelensis (Bti) in the chloroplast. Chlamydomonas has a number of advantages for this approach, including genetic controls that are not generally available with industrial algae. The Bti toxin has been used for mosquito control for > 30 years and does not engender resistance; it contains three Cry proteins, Cry4Aa (135 kDa), Cry4Ba (128 kDa) and Cry11Aa (72 kDa), and Cyt1Aa (25 kDa). To express the Cry proteins in the chloroplast, the three genes were resynthesized and cry4Aa was truncated to the first 700 amino acids (cry4Aa700 ); also, since they can be toxic to host cells, the inducible Cyc6:Nac2-psbD expression system was used. Western blots of total protein from the chloroplast transformants showed accumulation of the intact polypeptides, and the relative expression level was Cry11Aa > Cry4Aa700 > Cry4Ba. Quantitative western blots with purified Cry11Aa as a standard showed that Cry11Aa accumulated to 0.35% of total cell protein. Live cell bioassays in dH20 demonstrated toxicity of the cry4Aa700 and cry11Aa transformants to larvae of Aedes aegypti and Culex quinquefasciatus. These results demonstrate that the Cry proteins that are most toxic to Aedes and Culex mosquitoes, Cry4Aa and Cry11Aa, can be successfully expressed in the chloroplast of Chlamydomonas.
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Affiliation(s)
- Seongjoon Kang
- Dept. of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
- Pond Life Technologies LLC, Cedar Park, TX 78613, USA
| | - Obed W. Odom
- Dept. of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Saravanan Thangamani
- Dept. of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - David L. Herrin
- Dept. of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
- Pond Life Technologies LLC, Cedar Park, TX 78613, USA
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Shamriz S, Ofoghi H. Outlook in the application of Chlamydomonas reinhardtii chloroplast as a platform for recombinant protein production. Biotechnol Genet Eng Rev 2017; 32:92-106. [PMID: 28359189 DOI: 10.1080/02648725.2017.1307673] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microalgae, also called microphytes, are a vast group of microscopic photosynthetic organisms living in aquatic ecosystems. Microalgae have attracted the attention of biotechnology industry as a platform for extracting natural products with high commercial value. During last decades, microalgae have been also used as cost-effective and easily scalable platform for the production of recombinant proteins with medical and industrial applications. Most progress in this field has been made with Chlamydomonas reinhardtii as a model organism mainly because of its simple life cycle, well-established genetics and ease of cultivation. However, due to the scarcity of existing infrastructure for commercial production and processing together with relatively low product yields, no recombinant products from C. reinhardtii have gained approval for commercial production and most of them are still in research and development. In this review, we focus on the chloroplast of C. reinhardtii as an algal recombinant expression platform and compare its advantages and disadvantages to other currently used expression systems. We then discuss the strategies for engineering the chloroplast of C. reinhardtii to produce recombinant cells and present a comprehensive overview of works that have used this platform for the expression of high-value products.
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Affiliation(s)
- Shabnam Shamriz
- a Department of Biotechnology , Iranian Research Organization for Science and Technology , Tehran , Iran
| | - Hamideh Ofoghi
- a Department of Biotechnology , Iranian Research Organization for Science and Technology , Tehran , Iran
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37
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Batyrova K, Hallenbeck PC. Hydrogen Production by a Chlamydomonas reinhardtii Strain with Inducible Expression of Photosystem II. Int J Mol Sci 2017; 18:ijms18030647. [PMID: 28300765 PMCID: PMC5372659 DOI: 10.3390/ijms18030647] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 03/08/2017] [Accepted: 03/12/2017] [Indexed: 12/02/2022] Open
Abstract
Chlamydomonas reinhardtii cy6Nac2.49 is a genetically modified algal strain that activates photosynthesis in a cyclical manner, so that photosynthesis is not active constitutively in the presence of oxygen, but is turned on only in response to a metabolic trigger (anaerobiosis). Here, we further investigated hydrogen production by this strain comparing it with the parental wild-type strain under photoheterotrophic conditions in regular tris-acetate-phosphate (TAP) medium with a 10-h:14-h light/dark regime. Unlike the wild-type, whose level of H2 production remained low during illumination, H2 production in the mutant strain increased gradually with each subsequent light period, and by the final light period was significantly higher than the wild-type. The relatively low Photosystem II (PSII) activity of the mutant culture was shown by low fluorescence yield both in the dark (Fv/Fm) and in the light (δF/Fm’) periods. Measurement of oxygen evolution confirmed the low photosynthetic activity of the mutant cells, which gradually accumulated O2 to a lesser extent than the wild-type, thus allowing the mutant strain to maintain hydrogenase activity over a longer time period and to gradually accumulate H2 during periods of illumination. Therefore, controllable expression of PSII can be used to increase hydrogen production under nutrient replete conditions, thus avoiding many of the limitations associated with nutrient deprivation approaches sometimes used to promote hydrogen production.
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Affiliation(s)
- Khorcheska Batyrova
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, CP6128 Succursale Centre-ville, Montréal, Québec, QC H3C 3J7, Canada.
| | - Patrick C Hallenbeck
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, CP6128 Succursale Centre-ville, Montréal, Québec, QC H3C 3J7, Canada.
- Life Sciences Research Center, Department of Biology, United States Air Force Academy, Colorado Springs, CO 80840, USA.
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38
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Bayro-Kaiser V, Nelson N. Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen production. PHOTOSYNTHESIS RESEARCH 2016; 130:113-121. [PMID: 26951152 PMCID: PMC5054056 DOI: 10.1007/s11120-016-0232-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/11/2016] [Indexed: 05/28/2023]
Abstract
The need for energy and the associated burden are ever growing. It is crucial to develop new technologies for generating clean and efficient energy for society to avoid upcoming energetic and environmental crises. Sunlight is the most abundant source of energy on the planet. Consequently, it has captured our interest. Certain microalgae possess the ability to capture solar energy and transfer it to the energy carrier, H2. H2 is a valuable fuel, because its combustion produces only one by-product: water. However, the establishment of an efficient biophotolytic H2 production system is hindered by three main obstacles: (1) the hydrogen-evolving enzyme, [FeFe]-hydrogenase, is highly sensitive to oxygen; (2) energy conversion efficiencies are not economically viable; and (3) hydrogen-producing organisms are sensitive to stressful conditions in large-scale production systems. This study aimed to circumvent the oxygen sensitivity of this process with a cyclic hydrogen production system. This approach required a mutant that responded to high temperatures by reducing oxygen evolution. To that end, we randomly mutagenized the green microalgae, Chlamydomonas reinhardtii, to generate mutants that exhibited temperature-sensitive photoautotrophic growth. The selected mutants were further characterized by their ability to evolve oxygen and hydrogen at 25 and 37 °C. We identified four candidate mutants for this project. We characterized these mutants with PSII fluorescence, P700 absorbance, and immunoblotting analyses. Finally, we demonstrated that these mutants could function in a prototype hydrogen-producing bioreactor. These mutant microalgae represent a novel approach for sustained hydrogen production.
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Affiliation(s)
- Vinzenz Bayro-Kaiser
- Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Nathan Nelson
- Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel.
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Nagy V, Vidal-Meireles A, Tengölics R, Rákhely G, Garab G, Kovács L, Tóth SZ. Ascorbate accumulation during sulphur deprivation and its effects on photosystem II activity and H2 production of the green alga Chlamydomonas reinhardtii. PLANT, CELL & ENVIRONMENT 2016; 39:1460-72. [PMID: 26714836 DOI: 10.1111/pce.12701] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 11/25/2015] [Accepted: 12/18/2015] [Indexed: 05/10/2023]
Abstract
In nature, H2 production in Chlamydomonas reinhardtii serves as a safety valve during the induction of photosynthesis in anoxia, and it prevents the over-reduction of the photosynthetic electron transport chain. Sulphur deprivation of C. reinhardtii also triggers a complex metabolic response resulting in the induction of various stress-related genes, down-regulation of photosynthesis, the establishment of anaerobiosis and expression of active hydrogenase. Photosystem II (PSII) plays dual role in H2 production because it supplies electrons but the evolved O2 inhibits the hydrogenase. Here, we show that upon sulphur deprivation, the ascorbate content in C. reinhardtii increases about 50-fold, reaching the mM range; at this concentration, ascorbate inactivates the Mn-cluster of PSII, and afterwards, it can donate electrons to tyrozin Z(+) at a slow rate. This stage is followed by donor-side-induced photoinhibition, leading to the loss of charge separation activity in PSII and reaction centre degradation. The time point at which maximum ascorbate concentration is reached in the cell is critical for the establishment of anaerobiosis and initiation of H2 production. We also show that ascorbate influenced H2 evolution via altering the photosynthetic electron transport rather than hydrogenase activity and starch degradation.
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Affiliation(s)
- Valéria Nagy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - André Vidal-Meireles
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Roland Tengölics
- Department of Biotechnology, University of Szeged, Közép fasor 52, H-6726, Szeged, Hungary
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Közép fasor 52, H-6726, Szeged, Hungary
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Győző Garab
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Szilvia Z Tóth
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary
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40
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Oey M, Sawyer AL, Ross IL, Hankamer B. Challenges and opportunities for hydrogen production from microalgae. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:1487-99. [PMID: 26801871 PMCID: PMC5066674 DOI: 10.1111/pbi.12516] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 11/12/2015] [Accepted: 11/16/2015] [Indexed: 05/11/2023]
Abstract
The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050. Together with rising economic growth, this is forecast to result in a 50% increase in fuel demand, which will have to be met while reducing carbon dioxide (CO2 ) emissions by 50-80% to maintain social, political, energy and climate security. This tension between rising fuel demand and the requirement for rapid global decarbonization highlights the need to fast-track the coordinated development and deployment of efficient cost-effective renewable technologies for the production of CO2 neutral energy. Currently, only 20% of global energy is provided as electricity, while 80% is provided as fuel. Hydrogen (H2 ) is the most advanced CO2 -free fuel and provides a 'common' energy currency as it can be produced via a range of renewable technologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae, to power the next generation of H2 fuel cells. Microalgae production systems for carbon-based fuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating the potential of microalgal technologies for the commercial production of solar-driven H2 from water. It summarizes key global technology drivers, the potential and theoretical limits of microalgal H2 production systems, emerging strategies to engineer next-generation systems and how these fit into an evolving H2 economy.
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Affiliation(s)
- Melanie Oey
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Qld, Australia
| | | | - Ian Lawrence Ross
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Qld, Australia
| | - Ben Hankamer
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Qld, Australia
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41
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Doron L, Segal N, Shapira M. Transgene Expression in Microalgae-From Tools to Applications. FRONTIERS IN PLANT SCIENCE 2016; 7:505. [PMID: 27148328 PMCID: PMC4840263 DOI: 10.3389/fpls.2016.00505] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/29/2016] [Indexed: 05/17/2023]
Abstract
Microalgae comprise a biodiverse group of photosynthetic organisms that reside in water sources and sediments. The green microalgae Chlamydomonas reinhardtii was adopted as a useful model organism for studying various physiological systems. Its ability to grow under both photosynthetic and heterotrophic conditions allows efficient growth of non-photosynthetic mutants, making Chlamydomonas a useful genetic tool to study photosynthesis. In addition, this green alga can grow as haploid or diploid cells, similar to yeast, providing a powerful genetic system. As a result, easy and efficient transformation systems have been developed for Chlamydomonas, targeting both the chloroplast and nuclear genomes. Since microalgae comprise a rich repertoire of species that offer variable advantages for biotech and biomed industries, gene transfer technologies were further developed for many microalgae to allow for the expression of foreign proteins of interest. Expressing foreign genes in the chloroplast enables the targeting of foreign DNA to specific sites by homologous recombination. Chloroplast transformation also allows for the introduction of genes encoding several enzymes from a complex pathway, possibly as an operon. Expressing foreign proteins in the chloroplast can also be achieved by introducing the target gene into the nuclear genome, with the protein product bearing a targeting signal that directs import of the transgene-product into the chloroplast, like other endogenous chloroplast proteins. Integration of foreign genes into the nuclear genome is mostly random, resulting in large variability between different clones, such that extensive screening is required. The use of different selection modalities is also described, with special emphasis on the use of herbicides and metabolic markers which are considered to be friendly to the environment, as compared to drug-resistance genes that are commonly used. Finally, despite the development of a wide range of transformation tools and approaches, expression of foreign genes in microalgae suffers from low efficiency. Thus, novel tools have appeared in recent years to deal with this problem. Finally, while C. reinhardtii was traditionally used as a model organism for the development of transformation systems and their subsequent improvement, similar technologies can be adapted for other microalgae that may have higher biotechnological value.
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Abstract
In response to demands for sustainable domestic fuel sources, research into biofuels has become increasingly important. Many challenges face biofuels in their effort to replace petroleum fuels, but rational strain engineering of algae and photosynthetic organisms offers a great deal of promise. For decades, mutations and stress responses in photosynthetic microbiota were seen to result in production of exciting high-energy fuel molecules, giving hope but minor capability for design. However, '-omics' techniques for visualizing entire cell processing has clarified biosynthesis and regulatory networks. Investigation into the promising production behaviors of the model organism C. reinhardtii and its mutants with these powerful techniques has improved predictability and understanding of the diverse, complex interactions within photosynthetic organisms. This new equipment has created an exciting new frontier for high-throughput, predictable engineering of photosynthetically produced carbon-neutral biofuels.
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Affiliation(s)
- Hanna R Aucoin
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Joseph Gardner
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Nanette R Boyle
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA.
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Gimpel JA, Henríquez V, Mayfield SP. In Metabolic Engineering of Eukaryotic Microalgae: Potential and Challenges Come with Great Diversity. Front Microbiol 2015; 6:1376. [PMID: 26696985 PMCID: PMC4678203 DOI: 10.3389/fmicb.2015.01376] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 11/20/2015] [Indexed: 12/03/2022] Open
Abstract
The great phylogenetic diversity of microalgae is corresponded by a wide arrange of interesting and useful metabolites. Nonetheless metabolic engineering in microalgae has been limited, since specific transformation tools must be developed for each species for either the nuclear or chloroplast genomes. Microalgae as production platforms for metabolites offer several advantages over plants and other microorganisms, like the ability of GMO containment and reduced costs in culture media, respectively. Currently, microalgae have proved particularly well suited for the commercial production of omega-3 fatty acids and carotenoids. Therefore most metabolic engineering strategies have been developed for these metabolites. Microalgal biofuels have also drawn great attention recently, resulting in efforts for improving the production of hydrogen and photosynthates, particularly triacylglycerides. Metabolic pathways of microalgae have also been manipulated in order to improve photosynthetic growth under specific conditions and for achieving trophic conversion. Although these pathways are not strictly related to secondary metabolites, the synthetic biology approaches could potentially be translated to this field and will also be discussed.
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Affiliation(s)
- Javier A Gimpel
- Chemical and Biotechnology Engineering Department, Centre for Biotechnology and Bioengineering, Universidad de Chile Santiago, Chile
| | - Vitalia Henríquez
- Instituto de Biología, Pontificia Universidad Católica de Valparaíso Valparaiso, Chile
| | - Stephen P Mayfield
- Division of Biological Sciences, California Center for Algae Biotechnology, University of California, San Diego La Jolla, CA, USA
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Antal TK, Krendeleva TE, Tyystjärvi E. Multiple regulatory mechanisms in the chloroplast of green algae: relation to hydrogen production. PHOTOSYNTHESIS RESEARCH 2015; 125:357-81. [PMID: 25986411 DOI: 10.1007/s11120-015-0157-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 05/11/2015] [Indexed: 05/10/2023]
Abstract
A complex regulatory network in the chloroplast of green algae provides an efficient tool for maintenance of energy and redox balance in the cell under aerobic and anaerobic conditions. In this review, we discuss the structural and functional organizations of electron transport pathways in the chloroplast, and regulation of photosynthesis in the green microalga Chlamydomonas reinhardtii. The focus is on the regulatory mechanisms induced in response to nutrient deficiency stress and anoxia and especially on the role of a hydrogenase-mediated reaction in adaptation to highly reducing conditions and ATP deficiency in the cell.
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Affiliation(s)
- Taras K Antal
- Faculty of Biology, Moscow State University, Vorobyevi Gory, Moscow, 119992, Russia,
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45
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Ghirardi ML. Implementation of photobiological H2 production: the O 2 sensitivity of hydrogenases. PHOTOSYNTHESIS RESEARCH 2015; 125:383-93. [PMID: 26022106 DOI: 10.1007/s11120-015-0158-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/13/2015] [Indexed: 05/10/2023]
Abstract
The search for the ultimate carbon-free fuel has intensified in recent years, with a major focus on photoproduction of H2. Biological sources of H2 include oxygenic photosynthetic green algae and cyanobacteria, both of which contain hydrogenase enzymes. Although algal and cyanobacterial hydrogenases perform the same enzymatic reaction through metallo-clusters, their hydrogenases have evolved separately, are expressed differently (transcription of algal hydrogenases is anaerobically induced, while bacterial hydrogenases are constitutively expressed), and display different sensitivity to O2 inactivation. Among various physiological factors, the sensitivity of hydrogenases to O2 has been one of the major factors preventing implementation of biological systems for commercial production of renewable H2. This review addresses recent strategies aimed at engineering increased O2 tolerance into hydrogenases (as of now mainly unsuccessful), as well as towards the development of methods to bypass the O2 sensitivity of hydrogenases (successful but still yielding low solar conversion efficiencies). The author concludes with a description of current approaches from various laboratories to incorporate multiple genetic traits into either algae or cyanobacteria to jointly address limiting factors other than the hydrogenase O2 sensitivity and achieve more sustained H2 photoproduction activity.
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Affiliation(s)
- Maria L Ghirardi
- National Renewable Energy Laboratory, 15013 Denver West Pkway, Golden, CO, 80401, USA,
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46
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Activation of Autophagy by Metals in Chlamydomonas reinhardtii. EUKARYOTIC CELL 2015; 14:964-73. [PMID: 26163317 DOI: 10.1128/ec.00081-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 07/05/2015] [Indexed: 12/31/2022]
Abstract
Autophagy is an intracellular self-degradation pathway by which eukaryotic cells recycle their own material in response to specific stress conditions. Exposure to high concentrations of metals causes cell damage, although the effect of metal stress on autophagy has not been explored in photosynthetic organisms. In this study, we investigated the effect of metal excess on autophagy in the model unicellular green alga Chlamydomonas reinhardtii. We show in cells treated with nickel an upregulation of ATG8 that is independent of CRR1, a global regulator of copper signaling in Chlamydomonas. A similar effect on ATG8 was observed with copper and cobalt but not with cadmium or mercury ions. Transcriptome sequencing data revealed an increase in the abundance of the protein degradation machinery, including that responsible for autophagy, and a substantial overlap of that increased abundance with the hydrogen peroxide response in cells treated with nickel ions. Thus, our results indicate that metal stress triggers autophagy in Chlamydomonas and suggest that excess nickel may cause oxidative damage, which in turn activates degradative pathways, including autophagy, to clear impaired components and recover cellular homeostasis.
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47
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Mussgnug JH. Genetic tools and techniques for Chlamydomonas reinhardtii. Appl Microbiol Biotechnol 2015; 99:5407-18. [PMID: 26025017 DOI: 10.1007/s00253-015-6698-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/10/2015] [Accepted: 05/15/2015] [Indexed: 11/29/2022]
Abstract
The development of tools has always been a major driving force for the advancement of science. Optical microscopes were the first instruments that allowed discovery and descriptive studies of the subcellular features of microorganisms. Although optical and electron microscopes remained at the forefront of microbiological research tools since their inventions, the advent of molecular genetics brought about questions which had to be addressed with new "genetic tools". The unicellular green microalgal genus Chlamydomonas, especially the most prominent species C. reinhardtii, has become a frequently used model organism for many diverse fields of research and molecular genetic analyses of C. reinhardtii, as well as the available genetic tools and techniques, have become increasingly sophisticated throughout the last decades. The aim of this review is to provide an overview of the molecular key features of C. reinhardtii and summarize the progress related to the development of tools and techniques for genetic engineering of this organism, from pioneering DNA transformation experiments to state-of-the-art techniques for targeted nuclear genome editing and high-throughput screening approaches.
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Affiliation(s)
- Jan H Mussgnug
- Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstrasse 27, 33615, Bielefeld, Germany,
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Emadpour M, Karcher D, Bock R. Boosting riboswitch efficiency by RNA amplification. Nucleic Acids Res 2015; 43:e66. [PMID: 25824954 PMCID: PMC4446413 DOI: 10.1093/nar/gkv165] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/17/2015] [Accepted: 02/19/2015] [Indexed: 01/17/2023] Open
Abstract
Riboswitches are RNA sensors that regulate gene expression in response to binding of small molecules. Although they conceptually represent simple on/off switches and, therefore, hold great promise for biotechnology and future synthetic biology applications, the induction of gene expression by natural riboswitches after ligand addition or removal is often only moderate and, consequently, the achievable expression levels are not very high. Here, we have designed an RNA amplification-based system that strongly improves the efficiency of riboswitches. We have successfully implemented the method in a biological system for which currently no efficient endogenous tools for inducible (trans)gene expression are available: the chloroplasts of higher plants. We further show that an HIV antigen whose constitutive expression from the chloroplast genome is deleterious to the plant can be inducibly expressed under the control of the RNA amplification-enhanced riboswitch (RAmpER) without causing a mutant phenotype, demonstrating the potential of the method for the production of proteins and metabolites that are toxic to the host cell.
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Affiliation(s)
- Masoumeh Emadpour
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Daniel Karcher
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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Dubini A, Ghirardi ML. Engineering photosynthetic organisms for the production of biohydrogen. PHOTOSYNTHESIS RESEARCH 2015; 123:241-53. [PMID: 24671643 PMCID: PMC4331604 DOI: 10.1007/s11120-014-9991-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 02/17/2014] [Indexed: 05/24/2023]
Abstract
Oxygenic photosynthetic organisms such as green algae are capable of absorbing sunlight and converting the chemical energy into hydrogen gas. This process takes advantage of the photosynthetic apparatus of these organisms which links water oxidation to H2 production. Biological H2 has therefore the potential to be an alternative fuel of the future and shows great promise for generating large scale sustainable energy. Microalgae are able to produce H2 under light anoxic or dark anoxic condition by activating 3 different pathways that utilize the hydrogenases as catalysts. In this review, we highlight the principal barriers that prevent hydrogen production in green algae and how those limitations are being addressed, through metabolic and genetic engineering. We also discuss the major challenges and bottlenecks facing the development of future commercial algal photobiological systems for H2 production. Finally we provide suggestions for future strategies and potential new techniques to be developed towards an integrated system with optimized hydrogen production.
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Affiliation(s)
- Alexandra Dubini
- National Renewable Energy Laboratory, 15013 Denver West Parkway, Mail Box 3313, Golden, CO, 80401, USA,
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Bock R. Engineering plastid genomes: methods, tools, and applications in basic research and biotechnology. ANNUAL REVIEW OF PLANT BIOLOGY 2015; 66:211-41. [PMID: 25494465 DOI: 10.1146/annurev-arplant-050213-040212] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The small bacterial-type genome of the plastid (chloroplast) can be engineered by genetic transformation, generating cells and plants with transgenic plastid genomes, also referred to as transplastomic plants. The transformation process relies on homologous recombination, thereby facilitating the site-specific alteration of endogenous plastid genes as well as the precisely targeted insertion of foreign genes into the plastid DNA. The technology has been used extensively to analyze chloroplast gene functions and study plastid gene expression at all levels in vivo. Over the years, a large toolbox has been assembled that is now nearly comparable to the techniques available for plant nuclear transformation and that has enabled new applications of transplastomic technology in basic and applied research. This review describes the state of the art in engineering the plastid genomes of algae and land plants (Embryophyta). It provides an overview of the existing tools for plastid genome engineering, discusses current technological limitations, and highlights selected applications that demonstrate the immense potential of chloroplast transformation in several key areas of plant biotechnology.
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Affiliation(s)
- Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany;
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