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Proteomic and lipidomic analyses of lipid droplets in Aurantiochytrium limacinum ATCC MYA-1381. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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2
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Poliner E, Busch AWU, Newton L, Kim YU, Clark R, Gonzalez-Martinez SC, Jeong BR, Montgomery BL, Farré EM. Aureochromes maintain polyunsaturated fatty acid content in Nannochloropsis oceanica. PLANT PHYSIOLOGY 2022; 189:906-921. [PMID: 35166829 PMCID: PMC9157131 DOI: 10.1093/plphys/kiac052] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/12/2022] [Indexed: 05/05/2023]
Abstract
Nannochloropsis oceanica, like other stramenopile microalgae, is rich in long-chain polyunsaturated fatty acids (LC-PUFAs) such as eicosapentaenoic acid (EPA). We observed that fatty acid desaturases (FADs) involved in LC-PUFA biosynthesis were among the strongest blue light-induced genes in N. oceanica CCMP1779. Blue light was also necessary for maintaining LC-PUFA levels in CCMP1779 cells, and growth under red light led to a reduction in EPA content. Aureochromes are stramenopile-specific proteins that contain a light-oxygen-voltage (LOV)-sensing domain that associates with a flavin mononucleotide and is able to sense blue light. These proteins also contain a basic leucine zipper DNA-binding motif and can act as blue light-regulated transcription factors by associating with an E-box like motif, which we found enriched in the promoters of blue light-induced genes. We demonstrated that, in vitro, two CCMP1779 aureochromes were able to absorb blue light. Moreover, the loss or reduction of the expression of any of the three aureochrome genes led to a decrease in the blue light-specific induction of several FADs in CCMP1779. EPA content was also significantly reduced in NoAUREO2 and NoAUREO4 mutants. Taken together, our results indicate that aureochromes mediate blue light-dependent regulation of LC-PUFA content in N. oceanica CCMP1779 cells.
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Affiliation(s)
- Eric Poliner
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
- Cell and Molecular Biology Program, Michigan State University, East Lansing, Michigan, USA
| | - Andrea W U Busch
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Linsey Newton
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Young Uk Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Rachel Clark
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | | | - Byeong-Ryool Jeong
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandon Key Laboratory of Energy Genetics, Shandong Institute of Energy Research, Qingdao Institute of BioEnergy and Bioprocess Technology (QiBEBT), Chinese Academy of Sciences, Qingdao, Shandong 266101, China
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Beronda L Montgomery
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Eva M Farré
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
- Author for correspondence: (E.M.F.)
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3
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Shanta PV, Li B, Stuart DD, Cheng Q. Lipidomic Profiling of Algae with Microarray MALDI-MS toward Ecotoxicological Monitoring of Herbicide Exposure. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10558-10568. [PMID: 34286960 DOI: 10.1021/acs.est.1c01138] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Misuse of agrochemicals has a long-lasting negative impact on aquatic systems. Mismanagement of herbicides in agri-food sectors is often linked to a simultaneous decline in the health of downstream waterways. However, monitoring the herbicide levels in these areas is a laborious task, and modern analytical approaches, such as solid-phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) and enzyme-linked immunosorbent assay, are low-throughput and require significant sample preparation. We report here the use of microchip technology in combination with matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) for the assessment of the ecotoxicological effect of agrochemicals on aquatic species at the single-cell level. This approach quantifies the fluctuations in lipid content in sentinel organisms and targets the microalga, Chlamydomonas reinhardtii (C. reinhardtii), as the model system. Specifically, we investigated the cytotoxicity of three herbicides (atrazine, clomazone, and norflurazon) on C. reinhardtii by analyzing the lipid component variation upon assorted herbicide exposure. Lipidomic profiling reveals a significantly altered lipid content at >EC50 in atrazine-exposed cells. The response for norflurazon showed similar trends but diminished in magnitude, while the result for clomazone was near muted. At lower herbicide concentrations, digalactosyldiacylglycerols showed a rapid decrease in abundance, while several other lipids displayed a moderate increase. The microchip-based MALDI technique demonstrates the ability to achieve lipidomic profiling of aquatic species exposed to different stressors, proving effective for high-throughput screening and single-cell analysis in ecotoxicity studies.
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Affiliation(s)
- Peter V Shanta
- Environmental Toxicology, University of California, Riverside, California 92521, United States
| | - Bochao Li
- Environmental Toxicology, University of California, Riverside, California 92521, United States
| | - Daniel D Stuart
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Quan Cheng
- Environmental Toxicology, University of California, Riverside, California 92521, United States
- Department of Chemistry, University of California, Riverside, California 92521, United States
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4
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Zhang M, Xing Y, Wang F, Mi T, Zhen Y. Responses of triacylglycerol synthesis in Skeletonema marinoi to nitrogen and phosphate starvations. JOURNAL OF PHYCOLOGY 2020; 56:1505-1520. [PMID: 32602937 DOI: 10.1111/jpy.13044] [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: 02/12/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
Skeletonema marinoi is one of the most widespread marine planktonic diatoms in temperate coastal regions and sometimes can form massive blooms. Yet, the molecular mechanisms of triacylglycerol (TAG) synthesis in nutrient-deficient conditions for this species are still unknown. This study aimed to investigate how the TAG biosynthetic pathway of S. marinoi reacts to the culture age and nitrogen (N) or phosphorus (P) deficiency at molecular levels. Meanwhile, we also described the physiological and biochemical changes of S. marinoi in response to N or P starvation over time. To obtain reliable qRT-PCR data, six putative reference genes were identified for assessing expression stability using geNorm and BestKeeper software, and Actin exhibited the most stable expression across 45 tested S. marinoi samples. We found that the expression of TAG biosynthesis-related genes and ACCase enzyme activity varied in response to the different nutrient conditions and culture age. Taken together, we speculated that the capacity of TAG biosynthesis in S. marinoi is induced by N or P stress, and increases with culture age. Furthermore, TAG biosynthesis appears to respond more strongly to P deficiency than to N deficiency. Our study provides important insights into how diatoms regulate the TAG biosynthetic pathway when stressed by nutrient limitation. Besides, the data obtained from this study also provide useful clues for further exploring genes that can be used for metabolic engineering to enhance lipid production.
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Affiliation(s)
- Mei Zhang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, 266100, China
| | - Yongze Xing
- Fourth Institute of Oceanography, Ministry of Natural Resources, Beihai, 536002, China
| | - Fuwen Wang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, 266100, China
| | - Tiezhu Mi
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, 266100, China
| | - Yu Zhen
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, 266100, China
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5
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Azizan A, Maulidiani M, R. R, Shaari K, Ismail IS, Nagao N, Abas F. Mass Spectrometry-Based Metabolomics Combined with Quantitative Analysis of the Microalgal Diatom ( Chaetoceros calcitrans). Mar Drugs 2020; 18:md18080403. [PMID: 32751412 PMCID: PMC7459737 DOI: 10.3390/md18080403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/07/2020] [Accepted: 04/14/2020] [Indexed: 11/16/2022] Open
Abstract
Although many metabolomics studies of higher land plant species have been conducted, similar studies of lower nonland plant species, which include microalgae, are still developing. The present study represents an attempt to characterize the metabolic profile of a microalgal diatom Chaetoceros calcitrans, by applying high-resolution mass spectrometry detection, via Q-ExactiveTM Plus Orbitrap mass spectrometry. The results showed that 54 metabolites of various classes were tentatively identified. Experimentally, the chloroform and acetone extracts were clearly distinguished from other solvent extracts in chemometric regression analysis using PLS, showing the differences in the C. calcitrans metabolome between the groups. In addition, specific metabolites were evaluated, which supported the finding of antioxidant and anti-inflammatory activities. This study also provides data on the quantitative analysis of four carotenoids based on the identification results. Therefore, these findings could serve as a reliable tool for identifying and quantifying the metabolome that could reflect the metabolic activities of C. calcitrans.
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Affiliation(s)
- Awanis Azizan
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (A.A.); (M.M.); (K.S.); (I.S.I.)
| | - M. Maulidiani
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (A.A.); (M.M.); (K.S.); (I.S.I.)
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia
| | - Rudiyanto R.
- Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia;
| | - Khozirah Shaari
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (A.A.); (M.M.); (K.S.); (I.S.I.)
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
| | - Intan Safinar Ismail
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (A.A.); (M.M.); (K.S.); (I.S.I.)
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
| | - Norio Nagao
- Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
| | - Faridah Abas
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (A.A.); (M.M.); (K.S.); (I.S.I.)
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
- Correspondence: ; Tel.: +603-97698343
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Bouillaud D, Drouin D, Charrier B, Jacquemmoz C, Farjon J, Giraudeau P, Gonçalves O. Using benchtop NMR spectroscopy as an online non-invasive in vivo lipid sensor for microalgae cultivated in photobioreactors. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Zhang R, Lebovka N, Marchal L, Vorobiev E, Grimi N. Comparison of aqueous extraction assisted by pulsed electric energy and ultrasonication: Efficiencies for different microalgal species. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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8
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Shanta PV, Li B, Stuart DD, Cheng Q. Plasmonic Gold Templates Enhancing Single Cell Lipidomic Analysis of Microorganisms. Anal Chem 2020; 92:6213-6217. [DOI: 10.1021/acs.analchem.9b05285] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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9
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Munz J, Xiong Y, Kim JYH, Sung YJ, Seo S, Hong RH, Kariyawasam T, Shelley N, Lee J, Sim SJ, Jin E, Lee JH. Arginine-fed cultures generates triacylglycerol by triggering nitrogen starvation responses during robust growth in Chlamydomonas. ALGAL RES 2020. [DOI: 10.1016/j.algal.2019.101782] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Li-Beisson Y, Thelen JJ, Fedosejevs E, Harwood JL. The lipid biochemistry of eukaryotic algae. Prog Lipid Res 2019; 74:31-68. [PMID: 30703388 DOI: 10.1016/j.plipres.2019.01.003] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 02/06/2023]
Abstract
Algal lipid metabolism fascinates both scientists and entrepreneurs due to the large diversity of fatty acyl structures that algae produce. Algae have therefore long been studied as sources of genes for novel fatty acids; and, due to their superior biomass productivity, algae are also considered a potential feedstock for biofuels. However, a major issue in a commercially viable "algal oil-to-biofuel" industry is the high production cost, because most algal species only produce large amounts of oils after being exposed to stress conditions. Recent studies have therefore focused on the identification of factors involved in TAG metabolism, on the subcellular organization of lipid pathways, and on interactions between organelles. This has been accompanied by the development of genetic/genomic and synthetic biological tools not only for the reference green alga Chlamydomonas reinhardtii but also for Nannochloropsis spp. and Phaeodactylum tricornutum. Advances in our understanding of enzymes and regulatory proteins of acyl lipid biosynthesis and turnover are described herein with a focus on carbon and energetic aspects. We also summarize how changes in environmental factors can impact lipid metabolism and describe present and potential industrial uses of algal lipids.
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Affiliation(s)
- Yonghua Li-Beisson
- Aix-Marseille Univ, CEA, CNRS, BIAM, UMR7265, CEA Cadarache, Saint-Paul-lez Durance F-13108, France.
| | - Jay J Thelen
- Department of Biochemistry, University of Missouri, Christopher S. Bond Life Sciences Center, Columbia, MO 65211, United States.
| | - Eric Fedosejevs
- Department of Biochemistry, University of Missouri, Christopher S. Bond Life Sciences Center, Columbia, MO 65211, United States.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK.
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11
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Jones AD, Boundy-Mills KL, Barla GF, Kumar S, Ubanwa B, Balan V. Microbial Lipid Alternatives to Plant Lipids. Methods Mol Biol 2019; 1995:1-32. [PMID: 31148119 DOI: 10.1007/978-1-4939-9484-7_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lipids are in high demand in food production, nutritional supplements, detergents, lubricants, and biofuels. Different oil seeds produced from plants are conventionally extracted to yield lipids. With increasing population and reduced availability of cultivable land, conventional methods of producing lipids alone will not satisfy increasing demand. Lipids produced using different microbial sources are considered as sustainable alternative to plant derived lipids. Various microorganisms belonging to the genera of algae, bacteria, yeast, fungi, or marine-derived microorganisms such as thraustochytrids possess the ability to accumulate lipids in their cells. A variety of microbial production technologies are being used to cultivate these organisms under specific conditions using agricultural residues as carbon source to be cost competitive with plant derived lipids. Microbial oils, also known as single cell oils, have many advantages when compared with plant derived lipids, such as shorter life cycle, less labor required, season and climate independence, no use of arable land and ease of scale-up. In this chapter we compare the lipids derived from plants and different microorganisms. We also highlight various analytical techniques that are being used to characterize the lipids produced in oleaginous organisms and their applications in various processes.
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Affiliation(s)
- A Daniel Jones
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Kyria L Boundy-Mills
- Phaff Yeast Culture Collection, Department of Food Science and Technology, University of California, Davis, Davis, CA, USA
| | - G Florin Barla
- Faculty of Food Engineering, University of Suceava, Suceava, Romania
- Tyton Biosciences, Danville, VA, USA
| | - Sandeep Kumar
- Department of Civil and Environmental Engineering, Old Dominion University, Norfolk, VA, USA
| | - Bryan Ubanwa
- Department of Engineering Technology, Biotechnology Program, College of Technology, University of Houston, Houston, TX, USA
| | - Venkatesh Balan
- Department of Engineering Technology, Biotechnology Program, College of Technology, University of Houston, Houston, TX, USA.
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12
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Du ZY, Alvaro J, Hyden B, Zienkiewicz K, Benning N, Zienkiewicz A, Bonito G, Benning C. Enhancing oil production and harvest by combining the marine alga Nannochloropsis oceanica and the oleaginous fungus Mortierella elongata. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:174. [PMID: 29977335 PMCID: PMC6013958 DOI: 10.1186/s13068-018-1172-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/12/2018] [Indexed: 05/29/2023]
Abstract
BACKGROUND Although microalgal biofuels have potential advantages over conventional fossil fuels, high production costs limit their application in the market. We developed bio-flocculation and incubation methods for the marine alga, Nannochloropsis oceanica CCMP1779, and the oleaginous fungus, Mortierella elongata AG77, resulting in increased oil productivity. RESULTS By growing separately and then combining the cells, the M. elongata mycelium could efficiently capture N. oceanica due to an intricate cellular interaction between the two species leading to bio-flocculation. Use of a high-salt culture medium induced accumulation of triacylglycerol (TAG) and enhanced the contents of polyunsaturated fatty acids (PUFAs) including arachidonic acid and docosahexaenoic acid in M. elongata. To increase TAG productivity in the alga, we developed an effective, reduced nitrogen-supply regime based on ammonium in environmental photobioreactors. Under optimized conditions, N. oceanica produced high levels of TAG that could be indirectly monitored by following chlorophyll content. Combining N. oceanica and M. elongata to initiate bio-flocculation yielded high levels of TAG and total fatty acids, with ~ 15 and 22% of total dry weight (DW), respectively, as well as high levels of PUFAs. Genetic engineering of N. oceanica for higher TAG content in nutrient-replete medium was accomplished by overexpressing DGTT5, a gene encoding the type II acyl-CoA:diacylglycerol acyltransferase 5. Combined with bio-flocculation, this approach led to increased production of TAG under nutrient-replete conditions (~ 10% of DW) compared to the wild type (~ 6% of DW). CONCLUSIONS The combined use of M. elongata and N. oceanica with available genomes and genetic engineering tools for both species opens up new avenues to improve biofuel productivity and allows for the engineering of polyunsaturated fatty acids.
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Affiliation(s)
- Zhi-Yan Du
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
| | - Jonathan Alvaro
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
| | - Brennan Hyden
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Krzysztof Zienkiewicz
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Goettingen, Germany
| | - Nils Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
| | - Agnieszka Zienkiewicz
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 USA
| | - Gregory Bonito
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824 USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 USA
| | - Christoph Benning
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
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Willette S, Gill SS, Dungan B, Schaub TM, Jarvis JM, St. Hilaire R, Omar Holguin F. Alterations in lipidome and metabolome profiles of Nannochloropsis salina in response to reduced culture temperature during sinusoidal temperature and light. ALGAL RES 2018. [DOI: 10.1016/j.algal.2018.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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14
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Huete-Ortega M, Okurowska K, Kapoore RV, Johnson MP, Gilmour DJ, Vaidyanathan S. Effect of ammonium and high light intensity on the accumulation of lipids in Nannochloropsis oceanica (CCAP 849/10) and Phaeodactylum tricornutum (CCAP 1055/1). BIOTECHNOLOGY FOR BIOFUELS 2018; 11:60. [PMID: 29541157 PMCID: PMC5844138 DOI: 10.1186/s13068-018-1061-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 02/23/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Microalgae accumulate lipids when exposed to stressful conditions such as nutrient limitation that can be used to generate biofuels. Nitrogen limitation or deprivation is a strategy widely employed to elicit this response. However, this strategy is associated with a reduction in the microalgal growth, leading to overall poor lipid productivities. Here, we investigated the combined effect of a reduced source of nitrogen (ammonium) and super-saturating light intensities on the growth and induction of lipid accumulation in two model but diverse microalgal species, Phaeodactylum tricornutum and Nannochloropsis oceanica. We hypothesized that the lower energy cost of assimilating ammonium would allow the organisms to use more reductant power for lipid biosynthesis without compromising growth and that this would be further stimulated by the effect of high light (1000 µmol m-2 s-1) stress. We studied the changes in growth and physiology of both species when grown in culture media that either contained nitrate or ammonium as the nitrogen source, and an additional medium that contained ammonium with tungsten in place of molybdenum and compared this with growth in media without nitrogen. We focused our investigation on the early stages of exposure to the treatments to correspond to events relevant to induction of lipid accumulation in these two species. RESULTS At super-saturating light intensities, lipid productivity in P. tricornutum increased twofold when grown in ammonium compared to nitrogen free medium that increased further when tungsten was present in the medium in place of molybdenum. Conversely, N. oceanica growth and physiology was not compromised by the high light intensities used, and the use of ammonium had a negative effect on the lipid productivity, which was even more marked when tungsten was present. CONCLUSIONS Whilst the use of ammonium and super-saturating light intensities in P. tricornutum was revealed to be a good strategy for increasing lipid biosynthesis, no changes in the lipid productivity of N. oceanica were observed, under these conditions. Both results provide relevant direction for the better design of processes to produce biofuels in microalgae by manipulating growth conditions without the need to subject them to genetic engineering manipulation.
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Affiliation(s)
- María Huete-Ortega
- Department of Chemical and Biological Engineering, Advanced Biomanufacturing Centre, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
| | - Katarzyna Okurowska
- Department of Chemical and Biological Engineering, Advanced Biomanufacturing Centre, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK
| | - Rahul Vijay Kapoore
- Department of Chemical and Biological Engineering, Advanced Biomanufacturing Centre, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK
| | - Matthew P. Johnson
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield, UK
| | - D. James Gilmour
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield, UK
| | - Seetharaman Vaidyanathan
- Department of Chemical and Biological Engineering, Advanced Biomanufacturing Centre, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, UK
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15
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Poliner E, Pulman JA, Zienkiewicz K, Childs K, Benning C, Farré EM. A toolkit for Nannochloropsis oceanica CCMP1779 enables gene stacking and genetic engineering of the eicosapentaenoic acid pathway for enhanced long-chain polyunsaturated fatty acid production. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:298-309. [PMID: 28605577 PMCID: PMC5785352 DOI: 10.1111/pbi.12772] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/05/2017] [Accepted: 06/06/2017] [Indexed: 05/04/2023]
Abstract
Nannochloropsis oceanica is an oleaginous microalga rich in ω3 long-chain polyunsaturated fatty acids (LC-PUFAs) content, in the form of eicosapentaenoic acid (EPA). We identified the enzymes involved in LC-PUFA biosynthesis in N. oceanica CCMP1779 and generated multigene expression vectors aiming at increasing LC-PUFA content in vivo. We isolated the cDNAs encoding four fatty acid desaturases (FAD) and determined their function by heterologous expression in S. cerevisiae. To increase the expression of multiple fatty acid desaturases in N. oceanica CCMP1779, we developed a genetic engineering toolkit that includes an endogenous bidirectional promoter and optimized peptide bond skipping 2A peptides. The toolkit also includes multiple epitopes for tagged fusion protein production and two antibiotic resistance genes. We applied this toolkit, towards building a gene stacking system for N. oceanica that consists of two vector series, pNOC-OX and pNOC-stacked. These tools for genetic engineering were employed to test the effects of the overproduction of one, two or three desaturase-encoding cDNAs in N. oceanica CCMP1779 and prove the feasibility of gene stacking in this genetically tractable oleaginous microalga. All FAD overexpressing lines had considerable increases in the proportion of LC-PUFAs, with the overexpression of Δ12 and Δ5 FAD encoding sequences leading to an increase in the final ω3 product, EPA.
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Affiliation(s)
- Eric Poliner
- MSU‐DOE Plant Research LaboratoryMichigan State UniversityEast LansingMIUSA
- Cell and Molecular Biology ProgramMichigan State UniversityEast LansingMIUSA
| | - Jane A. Pulman
- Department of Plant BiologyMichigan State UniversityEast LansingMIUSA
| | - Krzysztof Zienkiewicz
- MSU‐DOE Plant Research LaboratoryMichigan State UniversityEast LansingMIUSA
- Department of Plant BiochemistryAlbrecht‐von‐Haller‐Institute for Plant SciencesGeorg‐August‐UniversityGottingenGermany
| | - Kevin Childs
- Department of Plant BiologyMichigan State UniversityEast LansingMIUSA
| | - Christoph Benning
- MSU‐DOE Plant Research LaboratoryMichigan State UniversityEast LansingMIUSA
- Department of Plant BiologyMichigan State UniversityEast LansingMIUSA
- Department of Biochemistry and Molecular BiologyMichigan State UniversityEast LansingMIUSA
| | - Eva M. Farré
- Department of Plant BiologyMichigan State UniversityEast LansingMIUSA
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16
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Yang M, Fan Y, Wu PC, Chu YD, Shen PL, Xue S, Chi ZY. An Extended Approach to Quantify Triacylglycerol in Microalgae by Characteristic Fatty Acids. FRONTIERS IN PLANT SCIENCE 2017; 8:1949. [PMID: 29181015 PMCID: PMC5693890 DOI: 10.3389/fpls.2017.01949] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/30/2017] [Indexed: 05/25/2023]
Abstract
Microalgae represent a third generation biofuel feedstock due to their high triacylglycerol (TAG) content under adverse environmental conditions. Microalgal TAG resides in a single cell and serves as a lipid class mixed with complicated compositions. We previously showed that TAG possessed characteristic fatty acids (CFAs) for quantification and was linearly correlated with the relative abundance of CFA within certain limits in microalgae. Here, we defined the application range of the linear correlation between TAG and CFA in the oleaginous microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum. In addition, TAG quantification was further expanded to a wide range of levels and the absolute amounts of saturated or monounsaturated CFAs, 16:0 and 18:1n9 of C. reinhardtii and 16:0 and 16:1n7 of P. tricornutum, instead of polyunsaturated CFAs, were verified to be linearly correlated to TAG levels throughout the entire period of nitrogen stress. This approach utilizes a single fatty acid to quantify TAG mixtures, and is rapid, simple and precise, which provides a useful tool for monitoring TAG accumulation of distinct microalgal species and facilitating high-throughput mutant screening for microalgae.
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Affiliation(s)
- Miao Yang
- School of Life Sciences and Biotechnology, Dalian University of Technology, Dalian, China
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yan Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Pei-Chun Wu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Ya-Dong Chu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Pei-Li Shen
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
- State Key Laboratory of Bioactive Seaweed Substances, Qingdao Bright Moon Seaweed Group Co., Ltd., Qingdao, China
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Zhan-You Chi
- School of Life Sciences and Biotechnology, Dalian University of Technology, Dalian, China
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17
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Nobusawa T, Hori K, Mori H, Kurokawa K, Ohta H. Differently localized lysophosphatidic acid acyltransferases crucial for triacylglycerol biosynthesis in the oleaginous alga Nannochloropsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 90:547-559. [PMID: 28218992 DOI: 10.1111/tpj.13512] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 02/07/2017] [Accepted: 02/08/2017] [Indexed: 05/04/2023]
Abstract
The production of renewable bioenergy will be necessary to meet rising global fossil fuel demands. Members of the marine microalgae genus Nannochloropsis produce large quantities of oils (triacylglycerols; TAGs), and this genus is regarded as one of the most promising for biodiesel production. Recent genome sequencing and transcriptomic studies on Nannochloropsis have provided a foundation for understanding its oleaginous trait, but the mechanism underlying oil accumulation remains to be clarified. Here we report Nannochloropsis knock-out strains of four extraplastidic lysophosphatidic acid acyltransferases (LPAT1-LPAT4) that catalyze a major de novo biosynthetic step of TAGs and membrane lipids. We found that the four LPATs are differently involved in lipid metabolic flow in Nannochloropsis. Double knock-outs among the LPATs revealed the pivotal LPATs for TAG biosynthesis, and localization analysis indicated that the stramenopile-specific LPATs (LPAT3 and LPAT4) associated with TAG synthesis reside at the perimeter of lipid droplets. No homologous region has been found with other lipid droplet-associated proteins, however. Lipid droplets are an organelle found in nearly all organisms, and recently they were shown to play important roles in cellular metabolism and signaling. Our results provide direct evidence for the importance of the perimeter of lipid droplet in TAG synthesis in addition to its known role in maintaining TAG stability, and these findings suggest that the oleaginous trait of Nannochloropsis is enabled by the acquisition of LPATs at the perimeter of lipid droplets.
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Affiliation(s)
- Takashi Nobusawa
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
- CREST, JST, Yokohama, Japan
| | - Koichi Hori
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
- CREST, JST, Yokohama, Japan
| | - Hiroshi Mori
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
- CREST, JST, Yokohama, Japan
| | - Ken Kurokawa
- CREST, JST, Yokohama, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, Japan
- Center for Information Biology, National Institute of Genetics, Yata 1111, Mishima, 411-8540, Japan
| | - Hiroyuki Ohta
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
- CREST, JST, Yokohama, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama, Japan
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18
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Røkke G, Melø TB, Hohmann-Marriott MF. The plastoquinone pool of Nannochloropsis oceanica is not completely reduced during bright light pulses. PLoS One 2017; 12:e0175184. [PMID: 28403199 PMCID: PMC5389811 DOI: 10.1371/journal.pone.0175184] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/21/2017] [Indexed: 11/18/2022] Open
Abstract
The lipid-producing model alga Nannochloropsis oceanica has a distinct photosynthetic machinery. This organism possesses chlorophyll a as its only chlorophyll species, and has a high ratio of PSI to PSII. This high ratio of PSI to PSII may affect the redox state of the plastoquinone pool during exposure to light, and consequently may play a role in activating photoprotection mechanisms. We utilized pulse-amplitude modulated fluorometry to investigate the redox state of the plastoquinone pool during and after bright light pulses. Our data indicate that even very intense (5910 μmol photons s-1m-2 of blue light having a wavelength of 440 nm) light pulses of 0.8 second duration are not sufficient to completely reduce the plastoquinone pool in Nannochloropsis. In order to achieve extensive reduction of the plastoquinone pool by bright light pulses, anaerobic conditions or an inhibitor of the photosynthetic electron transport chain has to be utilized. The implication of this finding for the application of the widely used saturating pulse method in algae is discussed.
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Affiliation(s)
- Gunvor Røkke
- Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Thor Bernt Melø
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
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19
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Jiao K, Chang J, Zeng X, Ng IS, Xiao Z, Sun Y, Tang X, Lin L. 5-Aminolevulinic acid promotes arachidonic acid biosynthesis in the red microalga Porphyridium purpureum. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:168. [PMID: 28670342 PMCID: PMC5485562 DOI: 10.1186/s13068-017-0855-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 06/19/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND The microalga Porphyridium purpureum within Rhodophyta abundantly produces several valuable proteins, polysaccharides, pigments and long-chain polyunsaturated fatty acid; it is especially effective in accumulating arachidonic acid (ARA). However, this high ARA yield is always achieved in conditions unfavourable for cell growth. In this study, we present a method for obtaining desirable ARA levels from P. purpureum while simultaneously promoting cell growth using appropriate concentrations of the growth hormone 5-Aminolevulinic acid (5-ALA). RESULTS Both the biomass and the ARA content of P. purpureum were enhanced by stimulation with 20 mg/L 5-ALA, leading to an optimal ARA yield of 170.32 mg/L-a 70.82% increase compared with control conditions. This ARA yield is the highest ever reported for microalgae. Based on variations in the fatty acid composition, total lipids, total proteins, total carbohydrates and pigment content during the cultivation period, we propose that the accumulation of ARA stimulated by 5-ALA occurs at the expense of other UFAs and total proteins, which may be related to decreased zeaxanthin. Lipidomic analysis revealed that triacylglycerols (TAGs) accounted for 47.5 ± 3.6% of all detected lipids, followed by phosphatidylglycerol (PG) and digalactosyldiacylglycerol (DGDG). As the levels of the most abundant TAGs increased under 5-ALA promotion and because 78.1 ± 3.4% (by weight) of detected TAG-branched chains contained ARA, the increase of ARA was mainly caused by TAG accumulation. CONCLUSIONS This work demonstrated a simple and effective strategy to promote both biomass and ARA yield in P. purpureum by introducing a small amount of 5-ALA. These results are helpful for understanding the microalgae metabolic pathways affected by phytohormones and for guiding the development of bioproducts from microalgae.
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Affiliation(s)
- Kailin Jiao
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
| | - Jingyu Chang
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
| | - Xianhai Zeng
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
- Xiamen Key Laboratory of High-valued Conversion Technology of Agricultural Biomass, Xiamen University, Xiamen, 361102 People’s Republic of China
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan, 701 Taiwan, ROC
| | - Zongyuan Xiao
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 People’s Republic of China
| | - Yong Sun
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
- Xiamen Key Laboratory of High-valued Conversion Technology of Agricultural Biomass, Xiamen University, Xiamen, 361102 People’s Republic of China
| | - Xing Tang
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
- Xiamen Key Laboratory of High-valued Conversion Technology of Agricultural Biomass, Xiamen University, Xiamen, 361102 People’s Republic of China
| | - Lu Lin
- College of Energy, Xiamen University, Xiamen, 361102 People’s Republic of China
- Xiamen Key Laboratory of High-valued Conversion Technology of Agricultural Biomass, Xiamen University, Xiamen, 361102 People’s Republic of China
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20
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Single-cell mass spectrometry reveals the importance of genetic diversity and plasticity for phenotypic variation in nitrogen-limited Chlamydomonas. ISME JOURNAL 2016; 11:988-998. [PMID: 27935588 DOI: 10.1038/ismej.2016.167] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/05/2016] [Accepted: 09/16/2016] [Indexed: 01/20/2023]
Abstract
Phenotypic variation is vital for microbial populations to survive environmental perturbations. Both genetic and non-genetic factors contribute to an organism's phenotypic variation and therefore its fitness. To investigate the correlation between genetic diversity and phenotypic variation, we applied our recently developed mass spectrometry method that allows for the simultaneous measurement of more than 25 different lipids and pigments with high throughput in the unicellular microalga Chlamydomonas reinhardtii. We monitored the impact of nitrogen limitation on a genetically diverse wild-type strain CC-1690 and two isoclonal isolates from CC-1690 named ANC3 and ANC5. Measuring molecular composition of thousands of single cells at different time points of the experiment allowed us to capture a dynamic picture of the phenotypic composition and adaptation of the populations over time. Although the genetically diverse population maintained phenotypic variation over the whole time course of the experiment, the isoclonal cultures showed higher synchronicity in their phenotypic response. Furthermore, the genetically diverse population showed equal or greater phenotypic variation over the whole time range in multidimensional trait space compared with isoclonal populations. However, along individual trait axes non-genetic variance was higher in isoclonal populations.
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21
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Furuhashi T, Nakamura T, Fragner L, Roustan V, Schön V, Weckwerth W. Biodiesel and poly-unsaturated fatty acids production from algae and crop plants - a rapid and comprehensive workflow for lipid analysis. Biotechnol J 2016; 11:1262-1267. [PMID: 27440175 DOI: 10.1002/biot.201400197] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/17/2016] [Accepted: 07/07/2016] [Indexed: 11/07/2022]
Abstract
Fatty acid methyl ester analysis (FAME) by gas chromatography coupled to mass spectrometry (GC-MS) is a widely used technique in biodiesel/bioproduct (e.g. poly-unsaturated fatty acids, PUFA) research but typically does not allow distinguishing between bound and free fatty acids. To understand and optimize biosynthetic pathways, however, the origin of the fatty acid is an important information. Furthermore the annotation of PUFAs is compromised in classical GC-EI-MS because the precursor molecular ion is missing. In the present protocol an alkaline methyl esterification step with TMS derivatization enabling the simultaneous analysis of bound and free fatty acids but also further lipids such as sterols in one GC-MS chromatogram is combined. This protocol is applied to different lipid extracts from single cell algae to higher plants: Chlorella vulgaris, Chlamydomonas reinhardtii, Coffea arabica, Pisum sativum and Cuscuta japonica. Further, field ionization (GC-FI-MS) is introduced for a better annotation of fatty acids and exact determination of the number of double bonds in PUFAs. The proposed workflow provides a convenient strategy to analyze algae and other plant crop systems with respect to their capacity for third generation biodiesel and high-quality bioproducts for nutrition such as PUFAs.
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Affiliation(s)
- Takeshi Furuhashi
- Department of Ecogenomics and Systems Biology, Vienna University, Vienna, Austria.
| | - Takemichi Nakamura
- Collaboration Promotion Unit, RIKEN Global Research Cluster, Wako,, Saitama, Japan
| | - Lena Fragner
- Department of Ecogenomics and Systems Biology, Vienna University, Vienna, Austria
| | - Valentin Roustan
- Department of Ecogenomics and Systems Biology, Vienna University, Vienna, Austria
| | - Verena Schön
- Department of Ecogenomics and Systems Biology, Vienna University, Vienna, Austria
- Ecoduna Produktions GmbH, Bruck/Leitha, Austria
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, Vienna University, Vienna, Austria.
- Vienna Metabolomics Center (VIME), Vienna University, Vienna, Austria.
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22
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Rai V, Karthikaichamy A, Das D, Noronha S, Wangikar PP, Srivastava S. Multi-omics Frontiers in Algal Research: Techniques and Progress to Explore Biofuels in the Postgenomics World. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2016; 20:387-99. [DOI: 10.1089/omi.2016.0065] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Vineeta Rai
- Department of Biosciences and Bioengineering, Proteomics Laboratory, Indian Institute of Technology Bombay, Mumbai, India
| | | | - Debasish Das
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, India
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology, Bombay, Mumbai, India
| | - Santosh Noronha
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology, Bombay, Mumbai, India
- Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Pramod P. Wangikar
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology, Bombay, Mumbai, India
- Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Sanjeeva Srivastava
- Department of Biosciences and Bioengineering, Proteomics Laboratory, Indian Institute of Technology Bombay, Mumbai, India
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology, Bombay, Mumbai, India
- Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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23
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Légeret B, Schulz-Raffelt M, Nguyen HM, Auroy P, Beisson F, Peltier G, Blanc G, Li-Beisson Y. Lipidomic and transcriptomic analyses of Chlamydomonas reinhardtii under heat stress unveil a direct route for the conversion of membrane lipids into storage lipids. PLANT, CELL & ENVIRONMENT 2016; 39:834-47. [PMID: 26477535 DOI: 10.1111/pce.12656] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/01/2015] [Accepted: 10/06/2015] [Indexed: 05/18/2023]
Abstract
Studying how photosynthetic cells modify membrane lipids in response to heat stress is important to understand how plants and microalgae adapt to daily fluctuations in temperature and to investigate new lipid pathways. Here, we investigate changes occurring in lipid molecular species and lipid metabolism genes during early response to heat stress in the model photosynthetic microorganism Chlamydomonas reinhardtii. Lipid molecular species analyses revealed that, after 60 min at 42 °C, a strong decrease in specific polyunsaturated membrane lipids was observed together with an increase in polyunsaturated triacylglycerols (TAGs) and diacylglycerols (DAGs). The fact that decrease in the major chloroplastic monogalactosyldiacylglycerol sn1-18:3/sn2-16:4 was mirrored by an accumulation of DAG sn1-18:3/sn2-16:4 and TAG sn1-18:3/sn2-16:4/sn3-18:3 indicated that newly accumulated TAGs were formed via direct conversion of monogalactosyldiacylglycerols to DAGs then TAGs. Lipidomic analyses showed that the third fatty acid of a TAG likely originated from a phosphatidylethanolamine or a diacylglyceryl-O-4'-(N,N,N,-trimethyl)-homoserine betaine lipid species. Candidate genes for this TAG synthesis pathway were provided through comparative transcriptomic analysis and included a phospholipase A2 homolog and the DAG acyltransferase DGTT1. This study gives insights into the molecular events underlying changes in membrane lipids during heat stress and reveals an alternative route for TAG synthesis.
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Affiliation(s)
- B Légeret
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - M Schulz-Raffelt
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - H M Nguyen
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - P Auroy
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - F Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - G Peltier
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
| | - G Blanc
- Laboratoire Information Génomique & Structurale, UMR7256 (IMM FR3479) CNRS Aix-Marseille Université, Marseille, France
| | - Y Li-Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR7265, Marseille, France
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24
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Hounslow E, Noirel J, Gilmour DJ, Wright PC. Lipid quantification techniques for screening oleaginous species of microalgae for biofuel production. EUR J LIPID SCI TECH 2016. [DOI: 10.1002/ejlt.201500469] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Emily Hounslow
- Department of Chemical and Biological Engineering; ChELSI Institute; The University of Sheffield; Sheffield UK
- Department of Molecular Biology and Biotechnology; The University of Sheffield; Sheffield UK
| | - Josselin Noirel
- Chaire de Bioinformatique; LGBA; Conservatoire National des Arts et Métiers; Paris France
| | - D. James Gilmour
- Department of Molecular Biology and Biotechnology; The University of Sheffield; Sheffield UK
| | - Phillip C. Wright
- Department of Chemical and Biological Engineering; ChELSI Institute; The University of Sheffield; Sheffield UK
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25
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Goncalves EC, Koh J, Zhu N, Yoo MJ, Chen S, Matsuo T, Johnson JV, Rathinasabapathi B. Nitrogen starvation-induced accumulation of triacylglycerol in the green algae: evidence for a role for ROC40, a transcription factor involved in circadian rhythm. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:743-57. [PMID: 26920093 DOI: 10.1111/tpj.13144] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 02/05/2016] [Accepted: 02/15/2016] [Indexed: 05/24/2023]
Abstract
Microalgal triacylglycerol (TAG), a promising source of biofuel, is induced upon nitrogen starvation (-N), but the proteins and genes involved in this process are poorly known. We performed isobaric tagging for relative and absolute quantification (iTRAQ)-based quantitative proteomics to identify Chlorella proteins with modulated expression under short-term -N. Out of 1736 soluble proteins and 2187 membrane-associated proteins identified, 288 and 56, respectively, were differentially expressed under -N. Gene expression analysis on select genes confirmed the same direction of mRNA modulation for most proteins. The MYB-related transcription factor ROC40 was the most induced protein, with a 9.6-fold increase upon -N. In a previously generated Chlamydomonas mutant, gravimetric measurements of crude total lipids revealed that roc40 was impaired in its ability to increase the accumulation of TAG upon -N, and this phenotype was complemented when wild-type Roc40 was expressed. Results from radiotracer experiments were consistent with the roc40 mutant being comparable to the wild type in recycling membrane lipids to TAG but being impaired in additional de novo synthesis of TAG during -N stress. In this study we provide evidence to support the hypothesis that transcription factor ROC40 has a role in -N-induced lipid accumulation, and uncover multiple previously unknown proteins modulated by short-term -N in green algae.
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Affiliation(s)
- Elton C Goncalves
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611-0690, USA
| | - Jin Koh
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA
| | - Ning Zhu
- Department of Biology, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Mi-Jeong Yoo
- Department of Biology, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Sixue Chen
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611-0690, USA
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA
- Department of Biology, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Takuya Matsuo
- Center for Gene Research, Nagoya University, Furo, Chikusa, Nagoya, 464-8602, Japan
| | - Jodie V Johnson
- Chemistry Department, University of Florida, Gainesville, FL, 32611, USA
| | - Bala Rathinasabapathi
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611-0690, USA
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Li-Beisson Y, Nakamura Y, Harwood J. Lipids: From Chemical Structures, Biosynthesis, and Analyses to Industrial Applications. Subcell Biochem 2016; 86:1-18. [PMID: 27023229 DOI: 10.1007/978-3-319-25979-6_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Lipids are one of the major subcellular components, and play numerous essential functions. As well as their physiological roles, oils stored in biomass are useful commodities for a variety of biotechnological applications including food, chemical feedstocks, and fuel. Due to their agronomic as well as economic and societal importance, lipids have historically been subjected to intensive studies. Major current efforts are to increase the energy density of cell biomass, and/or create designer oils suitable for specific applications. This chapter covers some basic aspects of what one needs to know about lipids: definition, structure, function, metabolism and focus is also given on the development of modern lipid analytical tools and major current engineering approaches for biotechnological applications. This introductory chapter is intended to serve as a primer for all subsequent chapters in this book outlining current development in specific areas of lipids and their metabolism.
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Affiliation(s)
- Yonghua Li-Beisson
- Institut de Biologie Environnementale et Biotechnologie, UMR 7265 CEA - CNRS - Université Aix Marseille, CEA Cadarache, Saint-Paul-lez-Durance, 13108, France.
| | - Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - John Harwood
- School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
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Li X, Jonikas MC. High-Throughput Genetics Strategies for Identifying New Components of Lipid Metabolism in the Green Alga Chlamydomonas reinhardtii. Subcell Biochem 2016; 86:223-247. [PMID: 27023238 DOI: 10.1007/978-3-319-25979-6_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Microalgal lipid metabolism is of broad interest because microalgae accumulate large amounts of triacylglycerols (TAGs) that can be used for biodiesel production (Durrett et al Plant J 54(4):593-607, 2008; Hu et al Plant J 54(4):621-639, 2008). Additionally, green algae are close relatives of land plants and serve as models to understand conserved lipid metabolism pathways in the green lineage. The green alga Chlamydomonas reinhardtii (Chlamydomonas hereafter) is a powerful model organism for understanding algal lipid metabolism. Various methods have been used to screen Chlamydomonas mutants for lipid amount or composition, and for identification of the mutated loci in mutants of interest. In this chapter, we summarize the advantages and caveats for each of these methods with a focus on screens for mutants with perturbed TAG content. We also discuss technical opportunities and new tools that are becoming available for screens of mutants altered in TAG content or perturbed in other processes in Chlamydomonas.
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Affiliation(s)
- Xiaobo Li
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Martin C Jonikas
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA.
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Abstract
Plant and algal oils are some of the most energy-dense renewable compounds provided by nature. Triacylglycerols (TAGs) are the major constituent of plant oils, which can be converted into fatty acid methyl esters commonly known as biodiesel. As one of the most efficient producers of TAGs, photosynthetic microalgae have attracted substantial interest for renewable fuel production. Currently, the big challenge of microalgae based TAGs for biofuels is their high cost compared to fossil fuels. A conundrum is that microalgae accumulate large amounts of TAGs only during stress conditions such as nutrient deprivation and temperature stress, which inevitably will inhibit growth. Thus, a better understanding of why and how microalgae induce TAG biosynthesis under stress conditions would allow the development of engineered microalgae with increased TAG production during conditions optimal for growth. Land plants also synthesize TAGs during stresses and we will compare new findings on environmental stress-induced TAG accumulation in plants and microalgae especially in the well-characterized model alga Chlamydomonas reinhardtii and a biotechnologically relevant genus Nannochloropsis.
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Affiliation(s)
- Zhi-Yan Du
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
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29
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Shen PL, Wang HT, Pan YF, Meng YY, Wu PC, Xue S. Identification of Characteristic Fatty Acids to Quantify Triacylglycerols in Microalgae. FRONTIERS IN PLANT SCIENCE 2016; 7:162. [PMID: 26941747 PMCID: PMC4761805 DOI: 10.3389/fpls.2016.00162] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 01/30/2016] [Indexed: 05/08/2023]
Abstract
The fatty acid profiles of lipids from microalgae are unique. Polyunsaturated fatty acids are generally enriched in polar lipids, whereas saturated and monounsaturated fatty acids constitute the majority of fatty acids in triacylglycerols (TAG). Each species has characteristic fatty acids, and their content is positively or negatively correlated with TAGs. The marine oleaginous diatom Phaeodactylum tricornutum was used as the paradigm to determine the quantitative relationship between TAG and characteristic fatty acid content. Fatty acid profiles and TAG content of Phaeodactylum tricornutum were determined in a time course. C16:0/C16:1 and eicosapentaenoic acid (EPA, C20:5n3) were identified as characteristic fatty acids in TAGs and polar lipids, respectively. The percentage of those characteristic fatty acids in total fatty acids had a significant linear relationship with TAG content, and thus, the correlation coefficient presenting r (2) were 0.96, 0.94, and 0.97, respectively. The fatty acid-based method for TAG quantification could also be applied to other microalgae such as Nannochloropsis oceanica in which the r (2) of C16:0 and EPA were 0.94 and 0.97, respectively, and in Chlorella pyrenoidosa r (2)-values for C18:1 and C18:3 with TAG content were 0.91 and 0.99, repectively. This characteristic fatty acid-based method provided a distinct way to quantify TAGs in microalgae, by which TAGs could be measured precisely by immediate transesterification from wet biomass rather than using conventional methods. This procedure simplified the operation and required smaller samples than conventional methods.
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Affiliation(s)
- Pei-Li Shen
- Marine Bioengineering Group, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- University of Chinese Academy of SciencesBeijing, China
| | - Hai-Tao Wang
- Marine Bioengineering Group, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- University of Chinese Academy of SciencesBeijing, China
| | - Yan-Fei Pan
- Department of Environmental Science and Engineering, College of Environment and Chemical Engineering, Dalian UniversityDalian, China
| | - Ying-Ying Meng
- School of Life Science and Biotechnology, Dalian University of TechnologyDalian, China
| | - Pei-Chun Wu
- Marine Bioengineering Group, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
| | - Song Xue
- Marine Bioengineering Group, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- *Correspondence: Song Xue
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Liang Y, Osada K, Sunaga Y, Yoshino T, Bowler C, Tanaka T. Dynamic oil body generation in the marine oleaginous diatom Fistulifera solaris in response to nutrient limitation as revealed by morphological and lipidomic analysis. ALGAL RES 2015. [DOI: 10.1016/j.algal.2015.09.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Yang D, Song D, Kind T, Ma Y, Hoefkens J, Fiehn O. Lipidomic Analysis of Chlamydomonas reinhardtii under Nitrogen and Sulfur Deprivation. PLoS One 2015; 10:e0137948. [PMID: 26375463 PMCID: PMC4574153 DOI: 10.1371/journal.pone.0137948] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 08/24/2015] [Indexed: 12/21/2022] Open
Abstract
Chlamydomonas reinhardtii accumulates lipids under complete nutrient starvation conditions while overall growth in biomass stops. In order to better understand biochemical changes under nutrient deprivation that maintain production of algal biomass, we used a lipidomic assay for analyzing the temporal regulation of the composition of complex lipids in C. reinhardtii in response to nitrogen and sulfur deprivation. Using a chip-based nanoelectrospray direct infusion into an ion trap mass spectrometer, we measured a diversity of lipid species reported for C. reinhardtii, including PG phosphatidylglycerols, PI Phosphatidylinositols, MGDG monogalactosyldiacylglycerols, DGDG digalactosyldiacylglycerols, SQDG sulfoquinovosyldiacylglycerols, DGTS homoserine ether lipids and TAG triacylglycerols. Individual lipid species were annotated by matching mass precursors and MS/MS fragmentations to the in-house LipidBlast mass spectral database and MS2Analyzer. Multivariate statistics showed a clear impact on overall lipidomic phenotypes on both the temporal and the nutrition stress level. Homoserine-lipids were found up-regulated at late growth time points and higher cell density, while triacyclglycerols showed opposite regulation of unsaturated and saturated fatty acyl chains under nutritional deprivation.
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Affiliation(s)
- Dawei Yang
- Zhong Yuan Academy of Biological Medicine, Liaocheng People's Hospital/Affiliated Liaocheng Hospital, Taishan Medical University, 67 Dong Chang Xi Lu, Liaocheng, Shandong, 252000, P. R. China
| | - Donghui Song
- Department of Marine Science, College of Marine Science & Engineering, Tianjin University of Science & Technology 29, the 13th St., TEDA, Tianjin, 300457, P. R. China
| | - Tobias Kind
- UC Davis Genome Center- Metabolomics, Davis, California 95616, United States of America
| | - Yan Ma
- UC Davis Genome Center- Metabolomics, Davis, California 95616, United States of America
| | - Jens Hoefkens
- Genedata Inc, Waltham, Massachusetts, United States of America
| | - Oliver Fiehn
- UC Davis Genome Center- Metabolomics, Davis, California 95616, United States of America
- King Abdulaziz University, Faculty of Science, Biochemistry Department, PO Box 80203, Jeddah 21589, Saudi Arabia
- * E-mail:
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32
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Allen JW, DiRusso CC, Black PN. Triacylglycerol synthesis during nitrogen stress involves the prokaryotic lipid synthesis pathway and acyl chain remodeling in the microalgae Coccomyxa subellipsoidea. ALGAL RES 2015. [DOI: 10.1016/j.algal.2015.04.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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33
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Simas-Rodrigues C, Villela HDM, Martins AP, Marques LG, Colepicolo P, Tonon AP. Microalgae for economic applications: advantages and perspectives for bioethanol. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:4097-108. [PMID: 25873683 DOI: 10.1093/jxb/erv130] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Renewable energy has attracted significant interest in recent years as a result of sustainability, environmental impact, and socio-economic considerations. Given existing technological knowledge and based on projections relating to biofuels derived from microalgae, microalgal feedstock is considered to be one of the most important renewable energy sources potentially available for industrial production. Therefore, this review examines microalgal bioethanol technology, which converts biomass from microalgae to fuel, the chemical processes involved, and possible ways of increasing the bioethanol yield, such as abiotic factors and genetic manipulation of fermenting organisms.
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Affiliation(s)
- Cíntia Simas-Rodrigues
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil
| | - Helena D M Villela
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil
| | - Aline P Martins
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil
| | - Luiza G Marques
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil
| | - Pio Colepicolo
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil
| | - Angela P Tonon
- Los Alamos National Laboratory, Bioscience Division, PO Box M888, Los Alamos, NM 87545, USA
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34
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Li-Beisson Y, Beisson F, Riekhof W. Metabolism of acyl-lipids in Chlamydomonas reinhardtii. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:504-522. [PMID: 25660108 DOI: 10.1111/tpj.12787] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/24/2015] [Accepted: 02/02/2015] [Indexed: 05/03/2023]
Abstract
Microalgae are emerging platforms for production of a suite of compounds targeting several markets, including food, nutraceuticals, green chemicals, and biofuels. Many of these products, such as biodiesel or polyunsaturated fatty acids (PUFAs), derive from lipid metabolism. A general picture of lipid metabolism in microalgae has been deduced from well characterized pathways of fungi and land plants, but recent advances in molecular and genetic analyses of microalgae have uncovered unique features, pointing out the necessity to study lipid metabolism in microalgae themselves. In the past 10 years, in addition to its traditional role as a model for photosynthetic and flagellar motility processes, Chlamydomonas reinhardtii has emerged as a model organism to study lipid metabolism in green microalgae. Here, after summarizing data on total fatty acid composition, distribution of acyl-lipid classes, and major acyl-lipid molecular species found in C. reinhardtii, we review the current knowledge on the known or putative steps for fatty acid synthesis, glycerolipid desaturation and assembly, membrane lipid turnover, and oil remobilization. A list of characterized or putative enzymes for the major steps of acyl-lipid metabolism in C. reinhardtii is included, and subcellular localizations and phenotypes of associated mutants are discussed. Biogenesis and composition of Chlamydomonas lipid droplets and the potential importance of lipolytic processes in increasing cellular oil content are also highlighted.
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Affiliation(s)
- Yonghua Li-Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, 13108, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique (CNRS), 13108, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR 7265, 13284, Marseille, France
| | - Fred Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, 13108, Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique (CNRS), 13108, Saint-Paul-lez-Durance, France
- Aix-Marseille Université, UMR 7265, 13284, Marseille, France
| | - Wayne Riekhof
- School of Biological Sciences and Center for Biological Chemistry, University of Nebraska - Lincoln, Lincoln, NE, 68588, USA
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35
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Goold H, Beisson F, Peltier G, Li-Beisson Y. Microalgal lipid droplets: composition, diversity, biogenesis and functions. PLANT CELL REPORTS 2015; 34:545-55. [PMID: 25433857 DOI: 10.1007/s00299-014-1711-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/12/2014] [Accepted: 11/19/2014] [Indexed: 05/03/2023]
Abstract
Lipid droplet is the major site of neutral lipid storage in eukaryotic cells, and increasing evidence show its involvement in numerous cellular processes such as lipid homeostasis, signaling, trafficking and inter-organelle communications. Although the biogenesis, structure, and functions of lipid droplets have been well documented for seeds of vascular plants, mammalian adipose tissues, insects and yeasts, relative little is known about lipid droplets in microalgae. Over the past 5 years, the growing interest of microalgae as a platform for biofuel, green chemicals or value-added polyunsaturated fatty acid production has brought algal lipid droplets into spotlight. Studies conducted on the green microalga Chlamydomonas reinhardtii and other model microalgae such as Haematococcus and Nannochloropsis species have led to the identification of proteins associated with lipid droplets, which include putative structural proteins different from plant oleosins and animal perilipins, as well as candidate proteins for lipid biosynthesis, mobilization, trafficking and homeostasis. Biochemical and microscopy studies have also started to shed light on the role of chloroplasts in the biogenesis of lipid droplets in Chlamydomonas.
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Affiliation(s)
- Hugh Goold
- CEA, IBEB, Lab Bioenerget Biotechnol Bacteries and Microalgues, Saint-Paul-lez-Durance, 13108, France
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36
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Luo Q, Li Y, Wang W, Fei X, Deng X. Genome-wide survey and expression analysis of Chlamydomonas reinhardtii U-box E3 ubiquitin ligases (CrPUBs) reveal a functional lipid metabolism module. PLoS One 2015; 10:e0122600. [PMID: 25822994 PMCID: PMC4378952 DOI: 10.1371/journal.pone.0122600] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/11/2015] [Indexed: 11/18/2022] Open
Abstract
E3 ubiquitin ligases determine the substrate specificity of ubiquitination. Plant U-box (PUB) E3 ligases, with a typical 70-amino acid U-box domain, participate in plant developmental processes and environmental responses. Thus far, 64 PUB proteins have been identified in Arabidopsis and 77 PUB proteins have been identified in Oryza. However, detailed studies on U-box genes in the model microalgae Chlamydomonas reinhardtii are lacking. Here, we present a comprehensive analysis of the genes encoding U-box family proteins in C. reinhardtii. Following BLASTP analysis, 30 full-length U-box genes were identified in the C. reinhardtii genome sequence. Bioinformatics analyses of CrPUB genes were performed to characterize the phylogenetic relationships, chromosomal locations and gene structures of each member. The 30 identified CrPUB proteins are clustered into 3 distinct subfamilies, and the genes for these proteins are unevenly distributed among 14 chromosomes. Furthermore, the quantitative real-time RT-PCR or semi-quantitative RT-PCR analysis of 30 CrPUB mRNA abundances under nitrogen starvation showed that 18 CrPUB genes were induced by N starvation and that 7 genes were repressed in the N-poor environment. We selected five CrPUB genes exhibiting marked changes in expression under N-free conditions for further analysis in RNAi experiments and examined the oil content of these gene-silenced transgenic strains. The silencing of CrPUB5 and CrPUB14, which are typically down-regulated under N starvation, induced 9.8%-45.0% and 14.4%-61.8% lipid accumulation, respectively. In contrast, the silencing of CrPUB11, CrPUB23 and CrPUB28, which are markedly up-regulated under N-free conditions, decreased the lipid content by 5.5%-27.8%, 8.1%-27.3% and 6.6%-27.9%, respectively. These results provide a useful reference for the identification and functional analysis of this gene family and fundamental information for microalgae lipid metabolism research.
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Affiliation(s)
- Qiulan Luo
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou, 571101, China
| | - Yajun Li
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou, 571101, China
| | - Wenquan Wang
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou, 571101, China
| | - Xiaowen Fei
- School of Science, Hainan Medical College, Haikou, 571101, China
| | - Xiaodong Deng
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou, 571101, China
- * E-mail:
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37
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Meng Y, Jiang J, Wang H, Cao X, Xue S, Yang Q, Wang W. The characteristics of TAG and EPA accumulation in Nannochloropsis oceanica IMET1 under different nitrogen supply regimes. BIORESOURCE TECHNOLOGY 2015; 179:483-489. [PMID: 25575208 DOI: 10.1016/j.biortech.2014.12.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 12/05/2014] [Accepted: 12/06/2014] [Indexed: 05/23/2023]
Abstract
The strategy of nitrogen limitation has been widely applied to enhance lipid production in microalgae. The changes of cellular composition, and the characteristics of triacylglycerol (TAG) and eicosapentaenoic acid (EPA) accumulation in Nannochloropsis oceanica IMET1 were investigated. The results revealed that after nitrogen limitation TAG rather than carbohydrate was the dominant carbon sink in N. oceanica IMET1. Different nitrogen supplementation strategies were applied in order to achieve high TAG and EPA productivity, respectively. Limited nitrogen was supplied to improve TAG production, and a maximum productivity of 29.44 mg L(-1) d(-1) was obtained, which was a 6.74-fold increase compared to nitrogen-depleted cultivation. The highest EPA productivity of 7.66 mg L(-1) d(-1) was achieved under nitrogen-replete cultivation, which is different from the condition for TAG maximum productivity because the EPA is in glycolipids and phospholipids mainly. The fatty acid composition analysis identified the source of acyl group in TAG accumulation.
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Affiliation(s)
- Yingying Meng
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 16023, China; School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China
| | - Junpeng Jiang
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 16023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haitao Wang
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 16023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xupeng Cao
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 16023, China
| | - Song Xue
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 16023, China.
| | - Qing Yang
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China
| | - Weiliang Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
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38
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Deng X, Fan X, Li P, Fei X. A photoperiod-regulating gene CONSTANS is correlated to lipid biosynthesis in Chlamydomonas reinhardtii. BIOMED RESEARCH INTERNATIONAL 2015; 2015:715020. [PMID: 25654119 PMCID: PMC4310486 DOI: 10.1155/2015/715020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 10/09/2014] [Accepted: 10/13/2014] [Indexed: 01/01/2023]
Abstract
Background. The regulation of lipid biosynthesis is essential in photosynthetic eukaryotic cells. Thus far, no regulatory genes have been reported in the lipid metabolism pathway. Plant CONSTANS (CO) gene regulates blooming by participating in photoperiod and biological clock. Apart from regulating photoperiod, the Chlamydomonas CO gene also regulates starch content. Results. In this study, the results showed that, under HSM-S condition, cells accumulated more lipids at short-day conditions than at long-day conditions. The silencing of the CrCO gene via RNA interference resulted in an increase in lipid content and an increase in triacylglyceride (TAG) level by 24.5%. CrCO RNAi strains accumulated more lipids at short-day conditions than at long-day conditions. The decrease in CrCO expression resulted in the increased expression of TAG biosynthesis-related genes, such as DGAT2, PAP2, and PDAT3, whereas CIS and FBP1 genes showed a decrease in their mRNA when the CrCO expression was suppressed. On the other hand, the overexpression of CrCO resulted in the decrease in lipid content and TAG level. Conclusions. The results of this study revealed a relationship between CrCO gene and lipid metabolism in Chlamydomonas, suggesting that increasing oil by suppressing CrCO expression in microalgae is feasible.
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Affiliation(s)
- Xiaodong Deng
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China
| | - Xinzhao Fan
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China
| | - Ping Li
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China
| | - Xiaowen Fei
- School of Science, Hainan Medical College, Haikou 571101, China
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Targeted expression of nuclear transgenes in Chlamydomonas reinhardtii with a versatile, modular vector toolkit. Appl Microbiol Biotechnol 2015; 99:3491-503. [DOI: 10.1007/s00253-014-6354-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 12/09/2014] [Accepted: 12/22/2014] [Indexed: 12/13/2022]
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40
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Terashima M, Freeman ES, Jinkerson RE, Jonikas MC. A fluorescence-activated cell sorting-based strategy for rapid isolation of high-lipid Chlamydomonas mutants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:147-59. [PMID: 25267488 PMCID: PMC4280329 DOI: 10.1111/tpj.12682] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 08/22/2014] [Accepted: 09/19/2014] [Indexed: 05/22/2023]
Abstract
There is significant interest in farming algae for the direct production of biofuels and valuable lipids. Chlamydomonas reinhardtii is the leading model system for studying lipid metabolism in green algae, but current methods for isolating mutants of this organism with a perturbed lipid content are slow and tedious. Here, we present the Chlamydomonas high-lipid sorting (CHiLiS) strategy, which enables enrichment of high-lipid mutants by fluorescence-activated cell sorting (FACS) of pooled mutants stained with the lipid-sensitive dye Nile Red. This method only takes 5 weeks from mutagenesis to mutant isolation. We developed a staining protocol that allows quantification of lipid content while preserving cell viability. We improved separation of high-lipid mutants from the wild type by using each cell's chlorophyll fluorescence as an internal control. We initially demonstrated 20-fold enrichment of the known high-lipid mutant sta1 from a mixture of sta1 and wild-type cells. We then applied CHiLiS to sort thousands of high-lipid cells from a pool of about 60,000 mutants. Flow cytometry analysis of 24 individual mutants isolated by this approach revealed that about 50% showed a reproducible high-lipid phenotype. We further characterized nine of the mutants with the highest lipid content by flame ionization detection and mass spectrometry lipidomics. All mutants analyzed had a higher triacylglycerol content and perturbed whole-cell fatty acid composition. One arbitrarily chosen mutant was evaluated by microscopy, revealing larger lipid droplets than the wild type. The unprecedented throughput of CHiLiS opens the door to a systems-level understanding of green algal lipid biology by enabling genome-saturating isolation of mutants in key genes.
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Affiliation(s)
- Mia Terashima
- Department of Plant Biology, Carnegie Institution for Science260 Panama Street, Stanford, CA, 94305, USA
| | - Elizabeth S Freeman
- Department of Plant Biology, Carnegie Institution for Science260 Panama Street, Stanford, CA, 94305, USA
- Department of Biology, Stanford UniversityStanford, CA, 94305, USA
| | - Robert E Jinkerson
- Department of Plant Biology, Carnegie Institution for Science260 Panama Street, Stanford, CA, 94305, USA
| | - Martin C Jonikas
- Department of Plant Biology, Carnegie Institution for Science260 Panama Street, Stanford, CA, 94305, USA
- *For correspondence (e-mail )
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Wang B, Zhang Z, Hu Q, Sommerfeld M, Lu Y, Han D. Cellular capacities for high-light acclimation and changing lipid profiles across life cycle stages of the green alga Haematococcus pluvialis. PLoS One 2014; 9:e106679. [PMID: 25221928 PMCID: PMC4164365 DOI: 10.1371/journal.pone.0106679] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 07/30/2014] [Indexed: 12/27/2022] Open
Abstract
The unicellular microalga Haematococcus pluvialis has emerged as a promising biomass feedstock for the ketocarotenoid astaxanthin and neutral lipid triacylglycerol. Motile flagellates, resting palmella cells, and cysts are the major life cycle stages of H. pluvialis. Fast-growing motile cells are usually used to induce astaxanthin and triacylglycerol biosynthesis under stress conditions (high light or nutrient starvation); however, productivity of biomass and bioproducts are compromised due to the susceptibility of motile cells to stress. This study revealed that the Photosystem II (PSII) reaction center D1 protein, the manganese-stabilizing protein PsbO, and several major membrane glycerolipids (particularly for chloroplast membrane lipids monogalactosyldiacylglycerol and phosphatidylglycerol), decreased dramatically in motile cells under high light (HL). In contrast, palmella cells, which are transformed from motile cells after an extended period of time under favorable growth conditions, have developed multiple protective mechanisms—including reduction in chloroplast membrane lipids content, downplay of linear photosynthetic electron transport, and activating nonphotochemical quenching mechanisms—while accumulating triacylglycerol. Consequently, the membrane lipids and PSII proteins (D1 and PsbO) remained relatively stable in palmella cells subjected to HL. Introducing palmella instead of motile cells to stress conditions may greatly increase astaxanthin and lipid production in H. pluvialis culture.
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Affiliation(s)
- Baobei Wang
- Department of Chemical and Biochemical Engineering, Xiamen University, Xiamen, Fujian, China
- Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America
| | - Zhen Zhang
- Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Milton Sommerfeld
- Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America
| | - Yinghua Lu
- Department of Chemical and Biochemical Engineering, Xiamen University, Xiamen, Fujian, China
- * E-mail: (DH); (YL)
| | - Danxiang Han
- Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America
- * E-mail: (DH); (YL)
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Triglyceride quantification by catalytic saturation and LC–MS/MS reveals an evolutionary divergence in regioisometry among green microalgae. ALGAL RES 2014. [DOI: 10.1016/j.algal.2014.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Expression and knockdown of the PEPC1 gene affect carbon flux in the biosynthesis of triacylglycerols by the green alga Chlamydomonas reinhardtii. Biotechnol Lett 2014; 36:2199-208. [PMID: 24966045 DOI: 10.1007/s10529-014-1593-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/12/2014] [Indexed: 12/22/2022]
Abstract
The regulation of lipid biosynthesis is important in photosynthetic eukaryotic cells. This regulation is facilitated by the direct synthesis of fatty acids and triacylglycerol (TAG), and by other controls of the main carbon metabolic pathway. In this study, knockdown of the mRNA expression of the Chlamydomonas phosphoenolpyruvate carboxylase isoform 1 (CrPEPC1) gene by RNA interference increased TAG level by 20 % but decreased PEPC activities in the corresponding transgenic algae by 39-50 %. The decrease in CrPEPC1 expression increased the expression of TAG biosynthesis-related genes, such as acyl-CoA:diacylglycerol acyltransferase and phosphatidate phosphatase. Conversely, CrPEPC1 over-expression decreased TAG level by 37 % and increased PEPC activities by 157-184 %. These observations suggest that the lipid content of algal cells can be controlled by regulating the CrPEPC1 gene.
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Rezanka T, Nedbalová L, Procházková L, Sigler K. Lipidomic profiling of snow algae by ESI-MS and silver-LC/APCI-MS. PHYTOCHEMISTRY 2014; 100:34-42. [PMID: 24548555 DOI: 10.1016/j.phytochem.2014.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/20/2014] [Accepted: 01/24/2014] [Indexed: 05/16/2023]
Abstract
The main analytical benefit of this study is the development of methods enabling a rapid determination of total lipids of algae by lipidomic analysis and detailed identification and quantification of a complex mixture of natural TAGs by silver-LC/APCI-MS and NARP-LC/APCI-MS. Both types of chromatography can readily identify, both qualitatively and semiquantitatively, triacylglycerols containing 16:3 and 16:4 acids in the molecule. We conclude that the genus Chloromonas is a major producer of C16 PUFAs mostly contained in TAGs. Since more detailed studies in this field have been stymied by the shortage of 16:3 and 16:4 FAs, we decided to study the alga Chloromonas as a potential biotechnological source of C16 PUFAs.
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Affiliation(s)
- Tomáš Rezanka
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague, Czech Republic.
| | - Linda Nedbalová
- Charles University in Prague, Faculty of Science, Department of Ecology, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Lenka Procházková
- Charles University in Prague, Faculty of Science, Department of Ecology, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Karel Sigler
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague, Czech Republic
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Deng X, Cai J, Fei X. Effect of the expression and knockdown of citrate synthase gene on carbon flux during triacylglycerol biosynthesis by green algae Chlamydomonas reinhardtii. BMC BIOCHEMISTRY 2013; 14:38. [PMID: 24373252 PMCID: PMC3890626 DOI: 10.1186/1471-2091-14-38] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 12/26/2013] [Indexed: 11/10/2022]
Abstract
Background The regulation of lipid biosynthesis is essential in photosynthetic eukaryotic cells. This regulation occurs during the direct synthesis of fatty acids and triacylglycerols (TAGs), as well as during other controlling processes in the main carbon metabolic pathway. Results In this study, the mRNA levels of Chlamydomonas citrate synthase (CrCIS) were found to decrease under nitrogen-limited conditions, which suggests suppressed gene expression. Gene silencing by RNA interference (RNAi) was conducted to determine whether CrCIS suppression affected the carbon flux in TAG biosynthesis. Results showed that the TAG level increased by 169.5%, whereas the CrCIS activities in the corresponding transgenic algae decreased by 16.7% to 37.7%. Moreover, the decrease in CrCIS expression led to the increased expression of TAG biosynthesis-related genes, such as acyl-CoA:diacylglycerol acyltransferase and phosphatidate phosphatase. Conversely, overexpression of CrCIS gene decreased the TAG level by 45% but increased CrCIS activity by 209% to 266% in transgenic algae. Conclusions The regulation of CrCIS gene can indirectly control the lipid content of algal cells. Our findings propose that increasing oil by suppressing CrCIS expression in microalgae is feasible.
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Affiliation(s)
| | | | - Xiaowen Fei
- School of Science, Hainan Medical College, Haikou 571101, China.
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