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Liu J, Sun Z, Mao X, Gerken H, Wang X, Yang W. Multiomics analysis reveals a distinct mechanism of oleaginousness in the emerging model alga Chromochloris zofingiensis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:1060-1077. [PMID: 30828893 DOI: 10.1111/tpj.14302] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/15/2019] [Accepted: 02/19/2019] [Indexed: 06/09/2023]
Abstract
Chromochloris zofingiensis, featured due to its capability to simultaneously synthesize triacylglycerol (TAG) and astaxanthin, is emerging as a leading candidate alga for production uses. To better understand the oleaginous mechanism of this alga, we conducted a multiomics analysis by systematically integrating time-resolved transcriptomes, lipidomes and metabolomes in response to nitrogen deprivation. The data analysis unraveled the distinct mechanism of TAG accumulation, which involved coordinated stimulation of multiple biological processes including supply of energy and reductants, carbon reallocation from protein and starch, and 'pushing' and 'pulling' carbon to TAG synthesis. Unlike the model alga Chlamydomonas, de novo fatty acid synthesis in C. zofingiensis was promoted, together with enhanced turnover of both glycolipids and phospholipids, supporting the drastic need of acyls for TAG assembly. Moreover, genomewide analysis identified many key functional enzymes and transcription factors that had engineering potential for TAG modulation. Two genes encoding glycerol-3-phosphate acyltransferase (GPAT), the first committed enzyme for TAG assembly, were found in the C. zofingiensis genome; in vivo functional characterization revealed that extrachloroplastic GPAT instead of chloroplastic GPAT played a central role in TAG synthesis. These findings illuminate distinct oleaginousness mechanisms in C. zofingiensis and pave the way towards rational manipulation of this alga to becone an emerging model for trait improvements.
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Affiliation(s)
- Jin Liu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Zheng Sun
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, 201306, China
| | - Xuemei Mao
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Henri Gerken
- School of Sustainable Engineering and the Built Environment, Arizona State University Polytechnic campus, Mesa, AZ, 85212, USA
| | - Xiaofei Wang
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Wenqiang Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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Xin Y, Shen C, She Y, Chen H, Wang C, Wei L, Yoon K, Han D, Hu Q, Xu J. Biosynthesis of Triacylglycerol Molecules with a Tailored PUFA Profile in Industrial Microalgae. MOLECULAR PLANT 2019; 12:474-488. [PMID: 30580039 DOI: 10.1016/j.molp.2018.12.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/29/2018] [Accepted: 12/13/2018] [Indexed: 05/06/2023]
Abstract
The composition of polyunsaturated fatty acids (PUFAs) in triacylglycerols (TAGs) is key to health benefits and for oil applications, yet the underlying genetic mechanism remains poorly understood. In this study, by in silico, ex vivo, and in vivo profiling of type-2 diacylglycerol acyltransferases (DGAT2s) in Nannochloropsis oceanica we revealed two novel PUFA-preferring enzymes that discriminate individual PUFA species in TAG assembly, with NoDGAT2J for linoleic acid (LA) and NoDGAT2K for eicosapentaenoic acid (EPA). The LA and EPA composition of TAG molecules is mediated in vivo via the functional partitioning between NoDGAT2J and 2K, both of which are localized in the chloroplast envelope. By modulating transcript abundance of the DGAT2s, an N. oceanica strain bank was created, where proportions of LA and EPA in TAG vary by 18.7-fold (between 0.21% and 3.92% dry weight) and 34.7-fold (between 0.09% and 3.12% dry weight), respectively. These findings lay the foundation for producing designer TAG molecules with tailored health benefits or for biofuel applications in industrial microalgae and higher-plant crops.
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Affiliation(s)
- Yi Xin
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chen Shen
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiting She
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Chen
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Cong Wang
- Core Laboratory, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Li Wei
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kangsup Yoon
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Danxiang Han
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Sun XM, Ren LJ, Zhao QY, Ji XJ, Huang H. Enhancement of lipid accumulation in microalgae by metabolic engineering. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:552-566. [DOI: 10.1016/j.bbalip.2018.10.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/30/2018] [Accepted: 10/05/2018] [Indexed: 01/08/2023]
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High level of reactive oxygen species inhibits triacylglycerols accumulation in Chlamydomonas reinhardtii. ALGAL RES 2019. [DOI: 10.1016/j.algal.2018.101400] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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55
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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: 175] [Impact Index Per Article: 35.0] [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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Xu Y, Falarz L, Chen G. Characterization of Type-2 Diacylglycerol Acyltransferases in the Green Microalga Chromochloris zofingiensis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:291-298. [PMID: 30543104 DOI: 10.1021/acs.jafc.8b05755] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step of the acyl-CoA-dependent TAG biosynthesis and thus is a key target for manipulating oil production in microalgae. The microalga Chromochloris zofingiensis can accumulate substantial amounts of triacylglycerol (TAG) and represents a promising source of algal lipids. In this study, C. zofingiensis DGAT2s (CzDGAT2s) were characterized with in silico, in vivo (yeast), and in vitro assays. Putative CzDGAT2s were identified, and their functional motifs and evolutionary relationship with other DGAT2s were analyzed. When CzDGAT2s were individually expressed in a TAG-deficient Saccharomyces cerevisiae strain, only CzDGAT2C could restore the TAG biosynthesis. Further in vitro assays indicated that CzDGAT2C displayed typical DGAT activity, which was fitted to the Michaelis-Menten equation, and N- and C-terminals were important for the enzyme activity. In addition, membrane yeast two-hybrid assay revealed a possible DGAT2 activity modulation via the formation of homodimer/heterodimer among different DGAT2 isoforms.
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Affiliation(s)
- Yang Xu
- Department of Agricultural, Food and Nutritional Science , University of Alberta , Edmonton , Alberta , Canada T6G 2P5
| | - Lucas Falarz
- Department of Agricultural, Food and Nutritional Science , University of Alberta , Edmonton , Alberta , Canada T6G 2P5
- Department of Biological Sciences , University of Manitoba , Winnipeg , Manitoba , Canada R3T 2N2
| | - Guanqun Chen
- Department of Agricultural, Food and Nutritional Science , University of Alberta , Edmonton , Alberta , Canada T6G 2P5
- Department of Biological Sciences , University of Manitoba , Winnipeg , Manitoba , Canada R3T 2N2
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Mao X, Wu T, Kou Y, Shi Y, Zhang Y, Liu J. Characterization of type I and type II diacylglycerol acyltransferases from the emerging model alga Chlorella zofingiensis reveals their functional complementarity and engineering potential. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:28. [PMID: 30792816 PMCID: PMC6371474 DOI: 10.1186/s13068-019-1366-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/30/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND The green alga Chlorella zofingiensis has been recognized as an industrially relevant strain because of its robust growth under multiple trophic conditions and the potential for simultaneous production of triacylglycerol (TAG) and the high-value keto-carotenoid astaxanthin. Nevertheless, the mechanism of TAG synthesis remains poorly understood in C. zofingiensis. Diacylglycerol acyltransferase (DGAT) is thought to catalyze the committed step of TAG assembly in the Kennedy pathway. C. zofingiensis genome is predicted to possess eleven putative DGAT-encoding genes, the greatest number ever found in green algae, pointing to the complexity of TAG assembly in the alga. RESULTS The transcription start site of C. zofingiensis DGATs was determined by 5'-rapid amplification of cDNA ends (RACE), and their coding sequences were cloned and verified by sequencing, which identified ten DGAT genes (two type I DGATs designated as CzDGAT1A and CzDGAT1B, and eight type II DGATs designated as CzDGTT1 through CzDGTT8) and revealed that the previous gene models of seven DGATs were incorrect. Function complementation in the TAG-deficient yeast strain confirmed the functionality of most DGATs, with CzDGAT1A and CzDGTT5 having the highest activity. In vitro DGAT assay revealed that CzDGAT1A and CzDGTT5 preferred eukaryotic and prokaryotic diacylglycerols (DAGs), respectively, and had overlapping yet distinctive substrate specificity for acyl-CoAs. Subcellular co-localization experiment in tobacco leaves indicated that both CzDGAT1A and CzDGTT5 were localized at endoplasmic reticulum (ER). Upon nitrogen deprivation, TAG was drastically induced in C. zofingiensis, accompanied by a considerable up-regulation of CzDGAT1A and CzDGTT5. These two genes were probably regulated by the transcription factors (TFs) bZIP3 and MYB1, as suggested by the yeast one-hybrid assay and expression correlation. Moreover, heterologous expression of CzDGAT1A and CzDGTT5 promoted TAG accumulation and TAG yield in different hosts including yeast and oleaginous alga. CONCLUSIONS Our study represents a pioneering work on the characterization of both type I and type II C. zofingiensis DGATs by systematically integrating functional complementation, in vitro enzymatic assay, subcellular localization, yeast one-hybrid assay and overexpression in yeast and oleaginous alga. These results (1) update the gene models of C. zofingiensis DGATs, (2) shed light on the mechanism of oleaginousness in which CzDGAT1A and CzDGTT5, have functional complementarity and probably work in collaboration at ER contributing to the abundance and complexity of TAG, and (3) provide engineering targets for future trait improvement via rational manipulation of this alga as well as other industrially relevant ones.
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Affiliation(s)
- Xuemei Mao
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Tao Wu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Yaping Kou
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Ying Shi
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Yu Zhang
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Jin Liu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
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Li N, Zhang Y, Meng H, Li S, Wang S, Xiao Z, Chang P, Zhang X, Li Q, Guo L, Igarashi Y, Luo F. Characterization of Fatty Acid Exporters involved in fatty acid transport for oil accumulation in the green alga Chlamydomonas reinhardtii. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:14. [PMID: 30651755 PMCID: PMC6330502 DOI: 10.1186/s13068-018-1332-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/06/2018] [Indexed: 05/03/2023]
Abstract
BACKGROUND In the past few decades, microalgae biofuel has become one of the most interesting sources of renewable energy. However, the higher cost of microalgae biofuel compared to that of petroleum prevented microalgae biofuel production. Therefore, the research on increasing lipid productivity from microalgae becomes more important. The lipid production source, triacylglycerol biosynthesis in microalgae requires short chain fatty acids as substrates, which are synthesized in chloroplasts. However, the transport mechanism of fatty acids from microalgae chloroplasts to cytosol remains unknown. RESULTS cDNAs from two homologs of the Arabidopsis fatty acid exporter 1 (FAX1) were cloned from Chlamydomonas reinhardtii and were named crfax1 and crfax2. Both CrFAXs were involved in fatty acid transport, and their substrates were mainly C16 and C18 fatty acids. Overexpression of both CrFAXs increased the accumulation of the total lipid content in algae cells, and the fatty acid compositions were changed under normal TAP or nitrogen deprivation conditions. Overexpression of both CrFAXs also increased the chlorophyll content. The MGDG content was decreased but the TAG, DAG, DGDG and other lipid contents were increased in CrFAXs overexpression strains. CONCLUSION These results reveal that CrFAX1 and CrFAX2 were involved in mediating fatty acid export for lipids biosynthesis in C. reinhardtii. In addition, overexpression of both CrFAXs obviously increased the intracellular lipid content, especially the triacylglycerol content in microalgae, which provides a potential technology for the production of more biofuels using microalgae.
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Affiliation(s)
- Nannan Li
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
- Academy of Agricultural Science, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Yan Zhang
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Hongjun Meng
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Shengting Li
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Shufeng Wang
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Zhongchun Xiao
- Academy of Agricultural Science, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Peng Chang
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Xiaohui Zhang
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Qing Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Liang Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Yasuo Igarashi
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
| | - Feng Luo
- Research Center of Bioremediation and Bioenergy, College of Resources and Environment, Southwest University, Beibei, Chongqing, 400715 People’s Republic of China
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Zienkiewicz K, Benning U, Siegler H, Feussner I. The type 2 acyl-CoA:diacylglycerol acyltransferase family of the oleaginous microalga Lobosphaera incisa. BMC PLANT BIOLOGY 2018; 18:298. [PMID: 30477429 PMCID: PMC6257963 DOI: 10.1186/s12870-018-1510-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/29/2018] [Indexed: 05/05/2023]
Abstract
BACKGROUND Oleaginous microalgae are promising sources of energy-rich triacylglycerols (TAGs) for direct use for food, feed and industrial applications. Lobosphaera incisa is a fresh water unicellular alga, which in response to nutrient stress accumulates a high amount of TAGs with a high proportion of arachidonic acid (ARA). The final committed step of de novo TAG biosynthesis is catalyzed by acyl-CoA:diacylglycerol acyltransferases (DGATs), which add a fatty acid (FA) to the final sn-3 position of diacylglycerol (DAG). RESULTS Genome analysis revealed the presence of five putative DGAT isoforms in L. incisa, including one DGAT of type 1, three DGATs of type 2 and a single isoform of a type 3 DGAT. For LiDGAT1, LiDGAT2.1, LiDGAT2.2 and LiDGAT2.3 enzyme activity was confirmed by expressing them in the TAG-deficient yeast strain H1246. Feeding experiments of yeast transformants with fatty acids suggest a broad substrate specificity spectrum for LiDGAT1. A significant TAG production in response to exogenous ARA was found for LiDGAT2.2. Cellular localization of the four type 1 and type 2 DGATs expressed in yeast revealed that they all localize to distinct ER domains. A prominent association of LiDGAT1 with ER domains in close proximity to forming lipid droplets (LDs) was also observed. CONCLUSIONS The data revealed a distinct molecular, functional and cellular nature of type 1 and type 2 DGATs from L. incisa, with LiDGAT1 being a major contributor to the TAG pool. LiDGATs of type 2 might be in turn involved in the incorporation of unusual fatty acids into TAG and thus regulate the composition of TAG. This report provides a valuable resource for the further research of microalgae DGATs oriented towards production of fresh-water strains with higher oil content of valuable composition, not only for oil industry but also for human and animal nutrition.
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Affiliation(s)
- Krzysztof Zienkiewicz
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, 37077 Goettingen, Germany
| | - Urs Benning
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, 37077 Goettingen, Germany
| | - Heike Siegler
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, 37077 Goettingen, Germany
| | - Ivo Feussner
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, 37077 Goettingen, Germany
- Department of Plant Biochemistry, Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, 37077 Goettingen, Germany
- Department of Plant Biochemistry, International Center for Advanced Studies of Energy Conversion (ICASEC), University of Goettingen, 37077 Goettingen, Germany
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Zhao W, Sun H, Ren Y, Wu T, He Y, Chen F. Chlorella zofingiensis as a promising strain in wastewater treatment. BIORESOURCE TECHNOLOGY 2018; 268:286-291. [PMID: 30086455 DOI: 10.1016/j.biortech.2018.07.144] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/27/2018] [Accepted: 07/28/2018] [Indexed: 06/08/2023]
Abstract
This study was conducted to evaluate the efficiency of treatment by C. zofingiensis, C. vulgaris and Scenedesmus sp. in terms of nutrient loading, lipid productivity and the activity of photosystem II. Results from nutrient loading suggested that the nitrogen loading of C. zofingiensis at 0.406 mg/L/h was higher than C. vulgaris and Scenedesmus sp., and the phosphorus loading of C. zofingiensis at 0.075 mg/L/h was higher than C. vulgaris. During the treating process, C. zofingiensis accumulated lipid with higher productivity of 26.57 mg/L/d than C. vulgaris and Scenedesmus sp. In combination with photosynthetic efficiency, C. zofingiensis possessed superior trophic transfer efficiency and absorption capability, even in worse environmental conditions. C. zofingiensis, therefore, exhibited the promising application prospect in wastewater treatment.
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Affiliation(s)
- Weiyang Zhao
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Han Sun
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Yuanyuan Ren
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Tao Wu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Yongjin He
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Feng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China.
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Zhang H, Zhang Z, Xiong T, Xiong X, Wu X, Guan C, Xiao G. The CCCH-type transcription factor BnZFP1 is a positive regulator to control oleic acid levels through the expression of diacylglycerol O-acyltransferase 1 gene in Brassica napus. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 132:633-640. [PMID: 30340175 DOI: 10.1016/j.plaphy.2018.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 06/08/2023]
Abstract
In China, the high-oleic acid rapeseed has an oil content of ∼42% and oleic acid (18:1) content of ∼80%. Compared to ordinary rapeseed, high-oleic acid rapeseed has higher levels of monounsaturated fatty acids and lower levels of saturated fatty acid and polyunsaturated fatty acids, and thus is of high nutritional and health value. In addition, high-oleic acid rapeseed oil imparts cardiovascular protective effects. Based on these properties, high-oleic acid oil crops have been extensively investigated and cultivated. We previously identified a CCCH-type transcription factor (BnZFP1, GenBank accession number XM_013796508) that is associated with high oleic acid traits from a Brassica napus subtractive hybridization library. In the present study, we overexpressed and silenced the BnZFP1 gene of B. napus. BnZFP1-overexpressing plants exhibited an 18.8% increase in oleic acid levels and a 3.8% increase in oil content. However, BNZFP1-silenced plants showed a 4.5% decrease in oleic acid levels, whereas no significant change in oil content was observed. Microarray and pull-down assays indicated that BnZFP1 has a total of thirty potential target genes. Further analysis and validation of one of the potential target genes, namely, diacylglycerol O-acyltransferases 1 (DGAT1) gene, indicated that it is positively regulated by BnZFP1. We also observed a correlation between elevated DGAT1 gene expression levels and higher oil content and oleic acid levels in rapeseed.
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Affiliation(s)
- Haiqiang Zhang
- Key Laboratory of Oil Crop Biology of Ministry of Agriculture, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, Hubei 430062, China; The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Zhenqian Zhang
- The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Teng Xiong
- The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Xinghua Xiong
- The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Xianmeng Wu
- Hunan Provincial Key Laboratory of Rice and Rapeseed Breeding for Disease Resistance, Changsha, Hunan, 410128, China
| | - Chunyun Guan
- The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China
| | - Gang Xiao
- Key Laboratory of Oil Crop Biology of Ministry of Agriculture, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, Hubei 430062, China; The National Oil Crops Improvement Center, Hunan Agricultural University, Changsha, Hunan, 410128, China; Hunan Provincial Key Laboratory of Rice and Rapeseed Breeding for Disease Resistance, Changsha, Hunan, 410128, China.
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Yang M, Meng Y, Chu Y, Fan Y, Cao X, Xue S, Chi Z. Triacylglycerol accumulates exclusively outside the chloroplast in short-term nitrogen-deprived Chlamydomonas reinhardtii. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:1478-1487. [PMID: 30266428 DOI: 10.1016/j.bbalip.2018.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 08/25/2018] [Accepted: 09/23/2018] [Indexed: 01/13/2023]
Abstract
In microalgae, triacylglycerol (TAG) biosynthesis occurs by parallel pathways involving both the chloroplast and endoplasmic reticulum. A better understanding of contribution of each pathway to TAG assembly facilitates enhanced TAG production via rational genetic engineering of microalgae. Here, using a UPLC-MS(/MS) coupled with TLC-GC-based lipidomic platform, the early response of the major glycerolipids to nitrogen stress was analyzed at both the cellular and chloroplastidic levels in the model green alga Chlamydomonas reinhardtii. Subcellular lipidomic analysis demonstrated that TAG was accumulated exclusively outside the chloroplast, and remained unaltered inside the chloroplast after 4 h of nitrogen starvation. This study ascertained the existence of the glycolipid, digalactosyldiacylglycerol (DGDG), outside the chloroplast and the betaine lipid, diacylglycerol-N,N,N-trimethylhomoserine (DGTS), inside the chloroplast. The newly synthesized DGDG and DGTS prominently increased at the extra-chloroplastidic compartments and served as the major precursors for TAG biosynthesis. In particular, DGDG contributed to the extra-chloroplastidic TAG assembly in form of diacylglycerol (DAG) and DGTS in form of acyl groups. The chloroplastidic membrane lipid, monogalactosyldiacylglycerol (MGDG), was proposed to primarily offer DAG for TAG formation outside the chloroplast. This study provides valuable insights into the subcellular glycerolipidomics and unveils the acyl flux into the extra-chloroplastidic TAG in microalgae.
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Affiliation(s)
- Miao Yang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
| | - Yingying Meng
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yadong Chu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Yan Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Xupeng Cao
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Zhanyou Chi
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
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63
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Sun H, Mao X, Wu T, Ren Y, Chen F, Liu B. Novel insight of carotenoid and lipid biosynthesis and their roles in storage carbon metabolism in Chlamydomonas reinhardtii. BIORESOURCE TECHNOLOGY 2018; 263:450-457. [PMID: 29772507 DOI: 10.1016/j.biortech.2018.05.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 05/26/2023]
Abstract
Revenues of carotenoid and lipid biosynthesis under excess light and nitrogen starvation were firstly analyzed for the increased biomass value through carbon metabolism analysis. The results suggested excess light and nitrogen starvation resulted in carbon partitioning among protein, starch, lipid and carotenoid. Nitrogen starvation promoted more cellular lipid content than excess light, while excess light promoted carotenoid and polyunsaturated fatty acid accumulation. In the molecular level, the stresses redirected carbon skeletons into the central metabolite of pyruvate and oriented into starch and lipid as the primary and secondary carbon storage, respectively. Economic estimation revealed nitrogen starvation potentially increased 14.76 × 10-6 and 72.11 × 10-6 $/g revenues of biofuel production at per batch and cell weight scales, respectively. Excess light could increase 63.90 × 10-6 and 19.21 × 10-6 $/g at per cell weight scale of lipid and carotenoid, respectively. In combination with metabolism analysis, conversion procedure of process-compatible products was divided into four phases.
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Affiliation(s)
- Han Sun
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Xuemei Mao
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Tao Wu
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Yuanyuan Ren
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Feng Chen
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Bin Liu
- Institute for Food & Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China.
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Zhu Z, Yuan G, Fan X, Fan Y, Yang M, Yin Y, Liu J, Liu Y, Cao X, Tian J, Xue S. The synchronous TAG production with the growth by the expression of chloroplast transit peptide-fused ScPDAT in Chlamydomonas reinhardtii. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:156. [PMID: 29928307 PMCID: PMC5989348 DOI: 10.1186/s13068-018-1160-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 05/31/2018] [Indexed: 05/17/2023]
Abstract
BACKGROUND The synchronous triacylglycerol (TAG) production with the growth is a key step to lower the cost of the microalgae-based biofuel production. Phospholipid: diacylglycerol acyltransferase (PDAT) has been identified recently and catalyzes the phospholipid contributing acyl group to diacylglycerol to synthesize TAG, and is considered as the important source of TAG in Chlamydomonas reinhardtii. RESULTS Using a chimeric Hsp70A-RbcS2 promoter, exogenous PDAT form Saccharomyces cerevisiae fused with a chloroplast transit peptide was expressed in C. reinhardtii CC-137. Proved by western blot, the expression of ScPDAT showed a synchronous trend to the growth in the exponential phase. Compared to the wild type, the strain of Scpdat achieved 22% increase in the content of total fatty acids and 32% increase in TAG content. In addition, the fluctuation of C16 series fatty acid in monogalactosyldiacylglycerol, diacylglyceryltrimethylhomoserine and TAG indicated an enhancement in the TAG accumulation pathway. CONCLUSION The TAG production was enhanced in the regular cultivation without the nutrient stress by strengthening the conversion of polar lipid to TAG in C. reinhardtii and the findings provide a candidate strategy for rational engineered strain to overcome the decline in the growth during the TAG accumulation triggered by nitrogen starvation.
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Affiliation(s)
- Zhen Zhu
- School of Bioengineering, Dalian Polytechnic University, Dalian, 116034 China
| | - Guangze Yuan
- School of Bioengineering, Dalian Polytechnic University, Dalian, 116034 China
| | - Xuran Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
| | - Yan Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Miao Yang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yalei Yin
- Key Laboratory of Separation Science for Analytical Chemistry, Scientific Research Center for Translational Medicine, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
| | - Jiao Liu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
| | - Yang Liu
- Key Laboratory of Separation Science for Analytical Chemistry, Scientific Research Center for Translational Medicine, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
| | - Xupeng Cao
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
| | - Jing Tian
- School of Bioengineering, Dalian Polytechnic University, Dalian, 116034 China
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China
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Mao X, Wu T, Sun D, Zhang Z, Chen F. Differential responses of the green microalga Chlorella zofingiensis to the starvation of various nutrients for oil and astaxanthin production. BIORESOURCE TECHNOLOGY 2018; 249:791-798. [PMID: 29136934 DOI: 10.1016/j.biortech.2017.10.090] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/25/2017] [Accepted: 10/26/2017] [Indexed: 05/03/2023]
Abstract
Chlorella zofingiensis has been proposed as a potential producer of lipids and the high-value carotenoid astaxanthin. In this study, the responses of photoautotrophic C. zofingiensis with respect to growth, lipid profiles and astaxanthin accumulation were investigated upon the starvation of N (NS), P (PS) and S (SS). NS and SS stimulated triacylglycerol (TAG) accumulation, which reached 27% and 21% of dry weight (DW), respectively. Stresses also stimulated astaxanthin accumulation greatly, reaching 3.9 mg/g DW by NS. SS led to the highest TAG productivity (52.4 mg L-1 d-1) while NS gave rise to the highest astaxanthin productivity (0.624 mg L-1 d-1). In combination with transcriptional analysis, a working model for stress-associated TAG and astaxanthin biosynthesis was proposed. Taken together, these detailed data shed light on the elucidation of differential responses to nutrient stresses and may provide insights into future engineering of this promising alga for improving TAG and astaxanthin production.
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Affiliation(s)
- Xuemei Mao
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Tao Wu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Dongzhe Sun
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Zhao Zhang
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China
| | - Feng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China; BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China.
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Endoplasmic reticulum acyltransferase with prokaryotic substrate preference contributes to triacylglycerol assembly in Chlamydomonas. Proc Natl Acad Sci U S A 2018; 115:1652-1657. [PMID: 29382746 DOI: 10.1073/pnas.1715922115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the unique features of triacylglycerol (TAG) metabolism in microalgae may be necessary to realize the full potential of these organisms for biofuel and biomaterial production. In the unicellular green alga Chlamydomonas reinhardtii a chloroplastic (prokaryotic) pathway has been proposed to play a major role in TAG precursor biosynthesis. However, as reported here, C. reinhardtii contains a chlorophyte-specific lysophosphatidic acid acyltransferase, CrLPAAT2, that localizes to endoplasmic reticulum (ER) membranes. Unlike canonical, ER-located LPAATs, CrLPAAT2 prefers palmitoyl-CoA over oleoyl-CoA as the acyl donor substrate. RNA-mediated suppression of CrLPAAT2 indicated that the enzyme is required for TAG accumulation under nitrogen deprivation. Our findings suggest that Chlamydomonas has a distinct glycerolipid assembly pathway that relies on CrLPAAT2 to generate prokaryotic-like TAG precursors in the ER.
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Cui Y, Zhao J, Wang Y, Qin S, Lu Y. Characterization and engineering of a dual-function diacylglycerol acyltransferase in the oleaginous marine diatom Phaeodactylum tricornutum. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:32. [PMID: 29449880 PMCID: PMC5806285 DOI: 10.1186/s13068-018-1029-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 01/23/2018] [Indexed: 05/03/2023]
Abstract
BACKGROUND Photosynthetic oleaginous microalgae are promising feedstocks for biofuels. Acyl-CoA:diacylglycerol acyltransferases (DGATs) represent rich sources for engineering microalgal lipid production. The principal activity of DGATs has been defined as a single-function enzyme catalyzing the esterification of diacylglycerol with acyl-CoA. RESULTS A dual-function PtWS/DGAT associated with diatom Phaeodactylum tricornutum is discovered in the current study. Distinctive to documented microalgal DGAT types, PtWS/DGAT exhibits activities of both a wax ester synthase (WS) and a DGAT. WS/DGATs are broadly distributed in microalgae, with different topology and phylogeny from those of DGAT1s, DGAT2s, and DGAT3s. In vitro and in vivo assays revealed that PtWS/DGAT, functioning as either a WS or a DGAT, exhibited a preference on saturated FA substrate. Endogenous overexpression of PtWS/DGAT demonstrated that the DGAT activity was dominant, whereas the WS activity was condition dependent and relatively minor. Compared with the wild type (WT), overexpression of PtWS/DGAT in the diatom resulted in increased levels of total lipids (TL) and triacylglycerol (TAG) regardless of nitrogen availability. The stability and scalability of the introduced traits were further investigated at a 10-L photobioreactor, where the mutant growth resembled WT, with moderately increased productivity of TL and TAG. Furthermore, the production of wax esters increased considerably (from undetectable levels to 2.83%) under nitrogen-deplete conditions. CONCLUSIONS PtWS/DGAT is a bifunctional enzyme and may serve as a promising target for the engineering of microalga-based oils and waxes for future industrial use.
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Affiliation(s)
- Yulin Cui
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Jialin Zhao
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
- University of Chinese Academy of Sciences, Beijing, 101408 China
| | - Yinchu Wang
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Song Qin
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228 China
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68
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Xin Y, Lu Y, Lee YY, Wei L, Jia J, Wang Q, Wang D, Bai F, Hu H, Hu Q, Liu J, Li Y, Xu J. Producing Designer Oils in Industrial Microalgae by Rational Modulation of Co-evolving Type-2 Diacylglycerol Acyltransferases. MOLECULAR PLANT 2017; 10:1523-1539. [PMID: 29107033 DOI: 10.1016/j.molp.2017.10.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/17/2017] [Accepted: 10/21/2017] [Indexed: 05/03/2023]
Abstract
Microalgal oils, depending on their degree of unsaturation, can be utilized as either nutritional supplements or fuels; thus, a feedstock with genetically designed and tunable degree of unsaturation is desirable to maximize process efficiency and product versatility. Systematic profiling of ex vivo (in yeast), in vitro, and in vivo activities of type-2 diacylglycerol acyltransferases in Nannochloropsis oceanica (NoDGAT2s or NoDGTTs), via reverse genetics, revealed that NoDGAT2A prefers saturated fatty acids (SFAs), NoDGAT2D prefers monounsaturated fatty acids (MUFAs), and NoDGAT2C exhibits the strongest activity toward polyunsaturated fatty acids (PUFAs). As NoDGAT2A, 2C, and 2D originated from the green alga, red alga, and eukaryotic host ancestral participants of secondary endosymbiosis, respectively, a mechanistic model of oleaginousness was unveiled, in which the indigenous and adopted NoDGAT2s formulated functional complementarity and specific transcript abundance ratio that underlie a rigid SFA:MUFA:PUFA hierarchy in triacylglycerol (TAG). By rationally modulating the ratio of NoDGAT2A:2C:2D transcripts, a bank of N. oceanica strains optimized for nutritional supplement or fuel production with a wide range of degree of unsaturation were created, in which proportion of SFAs, MUFAs, and PUFAs in TAG varied by 1.3-, 3.7-, and 11.2-fold, respectively. This established a novel strategy to simultaneously improve productivity and quality of oils from industrial microalgae.
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Affiliation(s)
- Yi Xin
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yandu Lu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi-Ying Lee
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA
| | - Li Wei
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Jia
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qintao Wang
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongmei Wang
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fali Bai
- Core Laboratory, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hanhua Hu
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Liu
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA; Institute for Food and Bioresource Engineering and Department of Energy and Resource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Yantao Li
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA.
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Physiological and Biochemical Changes Reveal Differential Patterns of Docosahexaenoic Acid Partitioning in Two Marine Algal Strains of Isochrysis. Mar Drugs 2017; 15:md15110357. [PMID: 29137149 PMCID: PMC5706046 DOI: 10.3390/md15110357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 10/31/2017] [Accepted: 11/06/2017] [Indexed: 01/08/2023] Open
Abstract
The marine microalgae Isochrysis are a good producer of natural docosahexaenoic acid (DHA). To better understand the patterns of DHA accumulation and distribution, two Isochrysis strains, CL153180 and CCMP462, were evaluated in this study. In a batch culture, CL153180 showed a decline in DHA content while CCMP462 exhibited a progressive increase during the late growth period when nitrogen was almost exhausted. In response to nitrogen deficiency (ND), both strains showed a considerable increase in neutral lipids (NL) at the expense of glycolipids (GL) but had little variation in phospholipids (PL). In CL153180, the DHA percentage of NL decreased gradually upon ND, while that in CCMP462 increased progressively to 21.4% after 4 days of ND, which is around 5-fold higher than CL153180. Accordingly, in contrast to CL153180 that stored DHA predominantly in GL, CCMP462 accumulated DHA mainly in NL in late days of ND. Taken together, we proposed a working model for the differential DHA partitioning patterns between two Isochrysis strains: for CCMP462, the degradation of GL released free fatty acids including DHA, which was incorporated into NL upon ND; whereas for CL153180, the released DHA from GL might not be incorporated into NL, and, consequently, might be subject to β-oxidation for degradation.
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Ma X, Yao L, Yang B, Lee YK, Chen F, Liu J. RNAi-mediated silencing of a pyruvate dehydrogenase kinase enhances triacylglycerol biosynthesis in the oleaginous marine alga Nannochloropsis salina. Sci Rep 2017; 7:11485. [PMID: 28904365 PMCID: PMC5597597 DOI: 10.1038/s41598-017-11932-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 08/31/2017] [Indexed: 01/01/2023] Open
Abstract
Oleaginous microalgae have been emerging as the third-generation feedstocks for biofuel production. Genetic manipulation for improving triacylglycerol (TAG) accumulation represents a promising approach towards the economics of microalgal biofuels. Acetyl-CoA, the essential carbon precursor for de novo fatty acid biosynthesis, can be derived from pyruvate catalyzed by pyruvate dehydrogenase, which is negatively regulated by pyruvate dehydrogenase kinase (PDK). In the present study, we characterized a PDK gene (NsPDK) from Nannochloropsis salina. Subcellular localization assay assisted by green fluorescence protein (GFP) fusion indicated the localization of NsPDK in mitochondria of N. salina cells. NsPDK knockdown via RNA interference strategy attenuated NsPDK expression at the mRNA level and its enzymatic activity in vivo, leading to faster TAG accumulation without compromising cell growth under high light stress conditions. Interestingly, the TAG increase was accompanied by a decline in membrane polar lipids. NsPDK knockdown also altered fatty acid profile in N. salina. Furthermore, transcriptional analysis suggested that the carbon metabolic pathways might be influenced by NsPDK knockdown leading to diverted carbon flux towards TAG synthesis. Taken together, our results demonstrate the role of NsPDK in regulating TAG accumulation and provide valuable insights into future manipulation of oleaginous microalgae for improving biofuel production.
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Affiliation(s)
- Xiaonian Ma
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871, China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871, China
| | - Lina Yao
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore, Singapore
| | - Bo Yang
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Yuan Kun Lee
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore, Singapore
| | - Feng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871, China.
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871, China.
| | - Jin Liu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871, China.
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871, China.
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71
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Yang M, Jiang JP, Xie X, Chu YD, Fan Y, Cao XP, Xue S, Chi ZY. Chloroplasts Isolation from Chlamydomonas reinhardtii under Nitrogen Stress. FRONTIERS IN PLANT SCIENCE 2017; 8:1503. [PMID: 28900438 PMCID: PMC5581827 DOI: 10.3389/fpls.2017.01503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 08/14/2017] [Indexed: 06/07/2023]
Abstract
Triacylglycerols are produced in abundance through chloroplast and endoplasmic reticulum pathways in some microalgae exposed to stress, though the relative contribution of either pathway remains elusive. Characterization of these pathways requires isolation of the organelles. In this study, an efficient and reproducible approach, including homogenous batch cultures of nitrogen-deprived algal cells in photobioreactors, gentle cell disruption using a simple custom-made disruptor with mechanical shear force, optimized differential centrifugation and Percoll density gradient centrifugation, was developed to isolate chloroplasts from Chlamydomonas reinhardtii subjected to nitrogen stress. Using this approach, the maximum limited stress duration was 4 h and the stressed cells exhibited 19 and 32% decreases in intracellular chlorophyll and nitrogen content, respectively. Chloroplasts with 48 - 300 μg chlorophyll were successfully isolated from stressed cells containing 10 mg chlorophyll. These stressed chloroplasts appeared intact, as monitored by ultrastructure observation and a novel quality control method involving the fatty acid biomarkers. This approach can provide sufficient quantities of intact stressed chloroplasts for subcellular biochemical studies in microalgae.
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Affiliation(s)
- Miao Yang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- University of Chinese Academy of SciencesBeijing, China
- School of Life Sciences and Biotechnology, Dalian University of TechnologyDalian, China
| | - Jun-Peng Jiang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- University of Chinese Academy of SciencesBeijing, China
| | - Xi Xie
- Liaoning Ocean and Fisheries Science Research InstituteDalian, China
| | - Ya-Dong Chu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
| | - Yan Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
- University of Chinese Academy of SciencesBeijing, China
| | - Xu-Peng Cao
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of SciencesDalian, China
| | - Zhan-You Chi
- School of Life Sciences and Biotechnology, Dalian University of TechnologyDalian, China
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Peng H, Moghaddam L, Brinin A, Williams B, Mundree S, Haritos VS. Functional assessment of plant and microalgal lipid pathway genes in yeast to enhance microbial industrial oil production. Biotechnol Appl Biochem 2017. [DOI: 10.1002/bab.1573] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Huadong Peng
- Department of Chemical Engineering; Monash University; Clayton Australia
| | - Lalehvash Moghaddam
- Centre for Tropical Crops and Biocommodities; Queensland University of Technology; Brisbane Australia
| | - Anthony Brinin
- Centre for Tropical Crops and Biocommodities; Queensland University of Technology; Brisbane Australia
| | - Brett Williams
- Centre for Tropical Crops and Biocommodities; Queensland University of Technology; Brisbane Australia
| | - Sagadevan Mundree
- Centre for Tropical Crops and Biocommodities; Queensland University of Technology; Brisbane Australia
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73
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Meng Y, Cao X, Yao C, Xue S, Yang Q. Identification of the role of polar glycerolipids in lipid metabolism and their acyl attribution for TAG accumulation in Nannochloropsis oceanica. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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74
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Zienkiewicz K, Zienkiewicz A, Poliner E, Du ZY, Vollheyde K, Herrfurth C, Marmon S, Farré EM, Feussner I, Benning C. Nannochloropsis, a rich source of diacylglycerol acyltransferases for engineering of triacylglycerol content in different hosts. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:8. [PMID: 28070221 PMCID: PMC5210179 DOI: 10.1186/s13068-016-0686-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/10/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Photosynthetic microalgae are considered a viable and sustainable resource for biofuel feedstocks, because they can produce higher biomass per land area than plants and can be grown on non-arable land. Among many microalgae considered for biofuel production, Nannochloropsis oceanica (CCMP1779) is particularly promising, because following nutrient deprivation it produces very high amounts of triacylglycerols (TAG). The committed step in TAG synthesis is catalyzed by acyl-CoA:diacylglycerol acyltransferase (DGAT). Remarkably, a total of 13 putative DGAT-encoding genes have been previously identified in CCMP1779 but most have not yet been studied in detail. RESULTS Based on their expression profile, six out of 12 type-2 DGAT-encoding genes (NoDGTT1-NoDGTT6) were chosen for their possible role in TAG biosynthesis and the respective cDNAs were expressed in a TAG synthesis-deficient mutant of yeast. Yeast expressing NoDGTT5 accumulated TAG to the highest level. Over-expression of NoDGTT5 in CCMP1779 grown in N-replete medium resulted in levels of TAG normally observed only after N deprivation. Reduced growth rates accompanied NoDGTT5 over-expression in CCMP1779. Constitutive expression of NoDGTT5 in Arabidopsis thaliana was accompanied by increased TAG content in seeds and leaves. A broad substrate specificity for NoDGTT5 was revealed, with preference for unsaturated acyl groups. Furthermore, NoDGTT5 was able to successfully rescue the Arabidopsis tag1-1 mutant by restoring the TAG content in seeds. CONCLUSIONS Taken together, our results identified NoDGTT5 as the most promising gene for the engineering of TAG synthesis in multiple hosts among the 13 DGAT-encoding genes of N. oceanica CCMP1779. Consequently, this study demonstrates the potential of NoDGTT5 as a tool for enhancing the energy density in biomass by increasing TAG content in transgenic crops used for biofuel production.
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Affiliation(s)
- Krzysztof Zienkiewicz
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Agnieszka Zienkiewicz
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Great Lakes Bioenergy Center, Michigan State University, East Lansing, MI 48824 USA
| | - Eric Poliner
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI 48824 USA
| | - Zhi-Yan Du
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Katharina Vollheyde
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Cornelia Herrfurth
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Sofia Marmon
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Dept. of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Eva M. Farré
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
| | - Ivo Feussner
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Department of Plant Biochemistry, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, 37073 Göttingen, Germany
- Department of Plant Biochemistry, International Center for Advanced Studies of Energy Conversion (ICASEC), Georg-August-University, 37073 Göttingen, Germany
| | - Christoph Benning
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Great Lakes Bioenergy Center, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
- Department Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
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75
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Yang B, Liu J, Ma X, Guo B, Liu B, Wu T, Jiang Y, Chen F. Genetic engineering of the Calvin cycle toward enhanced photosynthetic CO 2 fixation in microalgae. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:229. [PMID: 29034004 PMCID: PMC5629779 DOI: 10.1186/s13068-017-0916-8] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 09/26/2017] [Indexed: 05/18/2023]
Abstract
BACKGROUND Photosynthetic microalgae are emerging as potential biomass feedstock for sustainable production of biofuels and value-added bioproducts. CO2 biomitigation through these organisms is considered as an eco-friendly and promising alternative to the existing carbon sequestration methods. Nonetheless, the inherent relatively low photosynthetic capacity of microalgae has hampered the practical use of this strategy for CO2 biomitigation applications. RESULTS Here, we demonstrate the feasibility of improving photosynthetic capacity by the genetic manipulation of the Calvin cycle in the typical green microalga Chlorella vulgaris. Firstly, we fused a plastid transit peptide to upstream of the enhanced green fluorescent protein (EGFP) and confirmed its expression in the chloroplast of C. vulgaris. Then we introduced the cyanobacterial fructose 1,6-bisphosphate aldolase, guided by the plastid transit peptide, into C. vulgaris chloroplast, leading to enhanced photosynthetic capacity (~ 1.2-fold) and cell growth. Molecular and physiochemical analyses suggested a possible role for aldolase overexpression in promoting the regeneration of ribulose 1,5-bisphosphate in the Calvin cycle and energy transfer in photosystems. CONCLUSIONS Our work represents a proof-of-concept effort to enhance photosynthetic capacity by the engineering of the Calvin cycle in green microalgae. Our work also provides insights into targeted genetic engineering toward algal trait improvement for CO2 biomitigation uses.
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Affiliation(s)
- Bo Yang
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Jin Liu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, CREATE Tower, Singapore, 138602 Singapore
| | - Xiaonian Ma
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Bingbing Guo
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Bin Liu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Tao Wu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Yue Jiang
- Runke Bioengineering Co., Ltd., Zhangzhou, 363502 China
| | - Feng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
- Singapore-Peking University Research Centre for a Sustainable Low-Carbon Future, CREATE Tower, Singapore, 138602 Singapore
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76
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Wei H, Shi Y, Ma X, Pan Y, Hu H, Li Y, Luo M, Gerken H, Liu J. A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:174. [PMID: 28694845 PMCID: PMC5499063 DOI: 10.1186/s13068-017-0858-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 06/27/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND Photosynthetic oleaginous microalgae are considered promising feedstocks for biofuels. The marine microalga, Nannochloropsis oceanica, has been attracting ever-increasing interest because of its fast growth, high triacylglycerol (TAG) content, and available genome sequence and genetic tools. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step of TAG biosynthesis in the acyl-CoA-dependent pathway. Previous studies have identified 13 putative DGAT-encoding genes in the genome of N. oceanica, but the functional role of DGAT genes, especially type-I DGAT (DGAT1), remains ambiguous. RESULTS Nannochloropsis oceanica IMET1 possesses two DGAT1 genes: NoDGAT1A and NoDGAT1B. Functional complementation demonstrated the capability of NoDGAT1A rather than NoDGAT1B to restore TAG synthesis in a TAG-deficient yeast strain. In vitro DGAT assays revealed that NoDGAT1A preferred saturated/monounsaturated acyl-CoAs and eukaryotic diacylglycerols (DAGs) for TAG synthesis, while NoDGAT1B had no detectable enzymatic activity. Assisted with green fluorescence protein (GFP) fusion, fluorescence microscopy analysis indicated the localization of NoDGAT1A in the chloroplast endoplasmic reticulum (cER) of N. oceanica. NoDGAT1A knockdown caused ~25% decline in TAG content upon nitrogen depletion, accompanied by the reduced C16:0, C18:0, and C18:1 in TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. NoDGAT1A overexpression, on the other hand, led to ~39% increase in TAG content upon nitrogen depletion, accompanied by the enhanced C16:0 and C18:1 in the TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. Interestingly, NoDGAT1A overexpression also promoted TAG accumulation (by ~2.4-fold) under nitrogen-replete conditions without compromising cell growth, and TAG yield of the overexpression line reached 0.49 g L-1 at the end of a 10-day batch culture, 47% greater than that of the control line. CONCLUSIONS Taken together, our work demonstrates the functional role of NoDGAT1A and sheds light on the underlying mechanism for the biosynthesis of various TAG species in N. oceanica. NoDGAT1A resides likely in cER and prefers to transfer C16 and C18 saturated/monounsaturated fatty acids to eukaryotic DAGs for TAG assembly. This work also provides insights into the rational genetic engineering of microalgae by manipulating rate-limiting enzymes such as DGAT to modulate TAG biosynthesis and fatty acid composition for biofuel production.
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Affiliation(s)
- Hehong Wei
- Institute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Ying Shi
- Institute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Xiaonian Ma
- Institute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Yufang Pan
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 China
| | - Hanhua Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 China
| | - Yantao Li
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland Baltimore County, Baltimore, MA 21202 USA
| | - Ming Luo
- Guangdong Provincial Key Laboratory of Applied Botany, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China
| | - Henri Gerken
- School of Sustainable Engineering and the Built Environment, Arizona State University Polytechnic campus, Mesa, AZ 85212 USA
| | - Jin Liu
- Institute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
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77
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Current advances in molecular, biochemical, and computational modeling analysis of microalgal triacylglycerol biosynthesis. Biotechnol Adv 2016; 34:1046-1063. [DOI: 10.1016/j.biotechadv.2016.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/08/2016] [Accepted: 06/12/2016] [Indexed: 12/12/2022]
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78
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Liu J, Mao X, Zhou W, Guarnieri MT. Simultaneous production of triacylglycerol and high-value carotenoids by the astaxanthin-producing oleaginous green microalga Chlorella zofingiensis. BIORESOURCE TECHNOLOGY 2016; 214:319-327. [PMID: 27152772 DOI: 10.1016/j.biortech.2016.04.112] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 05/03/2023]
Abstract
The production of lipids and astaxanthin, a high-value carotenoid, by Chlorella zofingiensis was investigated under different culture conditions. Comparative analysis revealed a good correlation between triacylglycerol (TAG) and astaxanthin accumulation in C. zofingiensis. Stress conditions promoted cell size and weight and induced the accumulation of neutral lipids, especially TAG and astaxanthin, with a concomitant decrease in membrane lipids. The highest contents of TAG and astaxanthin achieved were 387 and 4.89mgg(-1) dry weight, respectively. A semi-continuous culture strategy was developed to optimize the TAG and astaxanthin productivities, which reached 297 and 3.3mgL(-1)day(-1), respectively. Additionally, astaxanthin accumulation was enhanced by inhibiting de novo fatty acid biosynthesis. In summary, our study represents a pioneering work of utilizing Chlorella for the integrated production of lipids and high-value products and C. zofingiensis has great potential to be a promising production strain and serve as an emerging oleaginous model alga.
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Affiliation(s)
- Jin Liu
- Institute for Food and Bioresource Engineering and Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Xuemei Mao
- Institute for Food and Bioresource Engineering and Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Wenguang Zhou
- School of Resources, Environmental & Chemical Engineering and MOE Biomass Engineering Research Center, Nanchang University, Nanchang, China; Center for Biorefining, Bioproducts and Biosystems Engineering Department, University of Minnesota, Saint Paul, MN 55108, USA
| | - Michael T Guarnieri
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
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79
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Liu XY, Ouyang LL, Zhou ZG. Phospholipid: diacylglycerol acyltransferase contributes to the conversion of membrane lipids into triacylglycerol in Myrmecia incisa during the nitrogen starvation stress. Sci Rep 2016; 6:26610. [PMID: 27216435 PMCID: PMC4877601 DOI: 10.1038/srep26610] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/05/2016] [Indexed: 11/21/2022] Open
Abstract
In addition to the Kennedy pathway for de novo biosynthesis, triacylglycerol (TAG), the most important stock for microalgae-based biodiesel production, can be synthesized by phospholipid: diacylglycerol acyltransferase (PDAT) that transfers an acyl group from phospholipids (PLs) to diacylglycerol (DAG). This study presents a novel gene that encodes PDAT from the green microalga Myrmecia incisa Reisigl H4301 (designated MiPDAT ). MiPDAT is localized on the plasma membrane (PM) via the agroinfiltration of tobacco leaves with a green fluorescent protein-fused construct. MiPDAT synthesizes TAG based on functional complementary experiments in the mutant yeast strain H1246 and the membrane lipid phosphatidylcholine (PC) is preferentially used as substrates as revealed by in vitro enzyme activity assay. The gradually increased transcription levels of MiPDAT in M. incisa during the cultivation under nitrogen starvation conditions is proposed to be responsible for the decrease and increase of the PC and TAG levels, respectively, as detected by liquid chromatography-mass spectrometry after 4 d of nitrogen starvation. In addition, the mechanism by which MiPDAT in this microalga uses PC to yield TAG is discussed. Accordingly, it is concluded that this PM-located PDAT contributes to the conversion of membrane lipids into TAG in M. incisa during the nitrogen starvation stress.
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Affiliation(s)
- Xiao-Yu Liu
- College of Aqua-life Sciences and Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Long-Ling Ouyang
- College of Aqua-life Sciences and Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Zhi-Gang Zhou
- College of Aqua-life Sciences and Technology, Shanghai Ocean University, Shanghai 201306, China
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80
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Ma XN, Chen TP, Yang B, Liu J, Chen F. Lipid Production from Nannochloropsis. Mar Drugs 2016; 14:md14040061. [PMID: 27023568 PMCID: PMC4849066 DOI: 10.3390/md14040061] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 03/01/2016] [Accepted: 03/11/2016] [Indexed: 12/18/2022] Open
Abstract
Microalgae are sunlight-driven green cell factories for the production of potential bioactive products and biofuels. Nannochloropsis represents a genus of marine microalgae with high photosynthetic efficiency and can convert carbon dioxide to storage lipids mainly in the form of triacylglycerols and to the ω-3 long-chain polyunsaturated fatty acid eicosapentaenoic acid (EPA). Recently, Nannochloropsis has received ever-increasing interests of both research and public communities. This review aims to provide an overview of biology and biotechnological potential of Nannochloropsis, with the emphasis on lipid production. The path forward for the further exploration of Nannochloropsis for lipid production with respect to both challenges and opportunities is also discussed.
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Affiliation(s)
- Xiao-Nian Ma
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Tian-Peng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Bo Yang
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Jin Liu
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Feng Chen
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing 100871, China.
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