1
|
Pan Y, Zhang W, Wang X, Jouhet J, Maréchal E, Liu J, Xia XQ, Hu H. Allele-dependent expression and functionality of lipid enzyme phospholipid:diacylglycerol acyltransferase affect diatom carbon storage and growth. PLANT PHYSIOLOGY 2024; 194:1024-1040. [PMID: 37930282 DOI: 10.1093/plphys/kiad581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/06/2023] [Accepted: 10/11/2023] [Indexed: 11/07/2023]
Abstract
In the acyl-CoA-independent pathway of triacylglycerol (TAG) synthesis unique to plants, fungi, and algae, TAG formation is catalyzed by the enzyme phospholipid:diacylglycerol acyltransferase (PDAT). The unique PDAT gene of the model diatom Phaeodactylum tricornutum strain CCMP2561 boasts 47 single nucleotide variants within protein coding regions of the alleles. To deepen our understanding of TAG synthesis, we observed the allele-specific expression of PDAT by the analysis of 87 published RNA-sequencing (RNA-seq) data and experimental validation. The transcription of one of the two PDAT alleles, Allele 2, could be specifically induced by decreasing nitrogen concentrations. Overexpression of Allele 2 in P. tricornutum substantially enhanced the accumulation of TAG by 44% to 74% under nutrient stress; however, overexpression of Allele 1 resulted in little increase of TAG accumulation. Interestingly, a more serious growth inhibition was observed in the PDAT Allele 1 overexpression strains compared with Allele 2 counterparts. Heterologous expression in yeast (Saccharomyces cerevisiae) showed that enzymes encoded by PDAT Allele 2 but not Allele 1 had TAG biosynthetic activity, and 7 N-terminal and 3 C-terminal amino acid variants between the 2 allele-encoded proteins substantially affected enzymatic activity. P. tricornutum PDAT, localized in the innermost chloroplast membrane, used monogalactosyldiacylglycerol and phosphatidylcholine as acyl donors as demonstrated by the increase of the 2 lipids in PDAT knockout lines, which indicated a common origin in evolution with green algal PDATs. Our study reveals unequal roles among allele-encoded PDATs in mediating carbon storage and growth in response to nitrogen stress and suggests an unsuspected strategy toward lipid and biomass improvement for biotechnological purposes.
Collapse
Affiliation(s)
- Yufang Pan
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Wanting Zhang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiaofei Wang
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing 100871, China
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CEA, CNRS, INRA, IRIG-LPCV, Grenoble Cedex 9 38054, France
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CEA, CNRS, INRA, IRIG-LPCV, Grenoble Cedex 9 38054, France
| | - Jin Liu
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing 100871, China
| | - Xiao-Qin Xia
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hanhua Hu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
2
|
Fu Z, Zhao T, Chu B, Gao W, Li T, Zhang Z, Li Q, Sun D. Low and high temperatures promote docosahexaenoic acid accumulation in Crypthecodinium sp. SUN by regulating the polyunsaturated fatty acid synthase pathway and the expression of saturated fatty acid preferred diacylglycerol acyltransferases. BIORESOURCE TECHNOLOGY 2023; 389:129850. [PMID: 37813314 DOI: 10.1016/j.biortech.2023.129850] [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: 08/24/2023] [Revised: 10/06/2023] [Accepted: 10/06/2023] [Indexed: 10/11/2023]
Abstract
Low (15 °C) and high (35 °C) temperatures significantly increased DHA as a percentage of total fatty acids (TFAs) to 43.6 % and 40.46 %, respectively (1.28- and 1.18-fold of that at 25 °C, respectively). The incompleteness of the FAS pathway indicates that DHA synthesis does not occur via this pathway. Meanwhile, Comparative transcriptome analysis showed that the PUFA synthase pathway might be responsible for DHA synthesis in C. sp. SUN. Additionally, the three diacylglycerol acyltransferases all had a substrate preference for saturated fatty acid (SFA)-CoA, which also contributed to the decreased SFA and increased DHA at both low and high temperatures. Additionally, WGCNA analysis identifies key regulatory genes that may be involved in temperature-regulated DHA proportion. The findings of this study indicate the mechanisms of temperature-regulated DHA accumulation in C. sp. SUN and shed light on the manipulation of DHA proportion by changes in temperature.
Collapse
Affiliation(s)
- Zhongxiang Fu
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China; School of Life Sciences, Hebei University, Baoding 071000, China
| | - Tiantian Zhao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Baijun Chu
- Nutrition & Health Research Institute, China National Cereals, Oils and Foodstuffs Corporation (COFCO), Beijing 102209, China
| | - Weizheng Gao
- School of Life Sciences, Hebei University, Baoding 071000, China
| | - Tong Li
- School of Life Sciences, Hebei University, Baoding 071000, China
| | - Zhao Zhang
- School of Life Sciences, Hebei University, Baoding 071000, China
| | - Qingyang Li
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
| | - Dongzhe Sun
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
| |
Collapse
|
3
|
Gu J, Xiao Y, Wu M, Wang A, Cui X, Xin Y, Paithoonrangsarid K, Lu Y. Artificial switches induce the bespoke production of functional compounds in marine microalgae Chlorella by neutralizing CO 2. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:143. [PMID: 37759320 PMCID: PMC10537470 DOI: 10.1186/s13068-023-02381-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/11/2023] [Indexed: 09/29/2023]
Abstract
To improve the CO2 tolerance of a marine microalga Chlorella sp. of which the production capacity has been demonstrated industrially, a mutant library was created and a strain hct53 was screened. Compared to the parental strain, hct53 shows a high CO2 capture capacity, while starch biosynthesis is compromised, with increases in health beneficial metabolites and antioxidant capacity. Global gene expression and genome-wide mutation distribution revealed that transcript choreography was concomitant with more active CO2 sequestration, an increase in the lipid synthesis, and a decrease in the starch and protein synthesis. These results suggest that artificial trait improvement via mutagenesis, couple with multiomics analysis, helps discover genetic switches that induce the bespoke conversion of carbon flow from "redundant metabolites" to valuable ones for functional food.
Collapse
Affiliation(s)
- Jiahua Gu
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Yuan Xiao
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Mingcan Wu
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Aoqi Wang
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Xinyu Cui
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Yi Xin
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China
| | - Kalyanee Paithoonrangsarid
- Biochemical Engineering and Systems Biology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
| | - Yandu Lu
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Biology and Fisheries, Hainan University, Haikou, 570228, China.
- Hainan Provincial Key Laboratory of Tropical Hydrobiotechnology, Hainan University, Haikou, China.
- Haikou Technology Innovation Center for Research and Utilization of Algal Bioresources, Hainan University, Haikou, China.
| |
Collapse
|
4
|
Gu X, Deng Y, Wang A, Gan Q, Xin Y, Paithoonrangsarid K, Lu Y. Engineering a marine microalga Chlorella sp. as the cell factory. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:133. [PMID: 37679828 PMCID: PMC10485975 DOI: 10.1186/s13068-023-02384-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/19/2023] [Indexed: 09/09/2023]
Abstract
The use of marine microalgae in industrial systems is attractive for converting CO2 into value-added products using saline water and sunlight. The plant nature and demonstrated industrial potential facilitate Chlorella spp. as excellent model organisms for both basic research and commercial application. However, the transformation method has not been developed in marine Chlorella spp., thus genetic engineering is hindered in exploiting the industrial potentialities of these strains. In this study, we provided a transformation protocol for the marine Chlorella strain MEM25, which showed robust characteristics, including high production of proteins and polyunsaturated fatty acids in multiple cultivation systems over various spatial-temporal scales. We showed that transformants could be obtained in a dramatically time-saving manner (comparable to Saccharomyces cerevisiae) with four functional proteins expressed properly. The transgenes are integrated into the genome and can be successfully inherited for more than two years. The development of a marine Chlorella transformation method, in combination with the complete genome, will greatly facilitate more comprehensive mechanism studies and provide possibilities to use this species as chassis for synthetic biology to produce value-added compounds with mutual advantage in neutralization of CO2 in commercial scales.
Collapse
Affiliation(s)
- Xinping Gu
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China
| | - Ying Deng
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China
| | - Aoqi Wang
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China
| | - Qinhua Gan
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China
| | - Yi Xin
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China
| | - Kalyanee Paithoonrangsarid
- Biochemical Engineering and Systems Biology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency at King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand
| | - Yandu Lu
- Single-cell BioEngineering Group, State Key Laboratory of Marine Resource Utilization in South China Sea, School of Marine Life and Aquaculture, Hainan University, Haikou, 570228, China.
- Hainan Provincial Key Laboratory of Tropical Hydrobiotechnology, Hainan University, Haikou, China.
- Haikou Technology Innovation Center for Research and Utilization of Algal Bioresources, Hainan University, Haikou, China.
| |
Collapse
|
5
|
Koh HG, Cho JM, Jeon S, Chang YK, Lee B, Kang NK. Transcriptional insights into Chlorella sp. ABC-001: a comparative study of carbon fixation and lipid synthesis under different CO 2 conditions. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:113. [PMID: 37454088 PMCID: PMC10350272 DOI: 10.1186/s13068-023-02358-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/11/2023] [Indexed: 07/18/2023]
Abstract
BACKGROUND Microalgae's low tolerance to high CO2 concentrations presents a significant challenge for its industrial application, especially when considering the utilization of industrial exhaust gas streams with high CO2 content-an economically and environmentally attractive option. Therefore, the objectives of this study were to investigate the metabolic changes in carbon fixation and lipid accumulation of microalgae under ambient air and high CO2 conditions, deepen our understanding of the molecular mechanisms driving these processes, and identify potential target genes for metabolic engineering in microalgae. To accomplish these goals, we conducted a transcriptomic analysis of the high CO2-tolerant strain, Chlorella sp. ABC-001, under two different carbon dioxide levels (ambient air and 10% CO2) and at various growth phases. RESULTS Cells cultivated with 10% CO2 exhibited significantly better growth and lipid accumulation rates, achieving up to 2.5-fold higher cell density and twice the lipid content by day 7. To understand the relationship between CO2 concentrations and phenotypes, transcriptomic analysis was conducted across different CO2 conditions and growth phases. According to the analysis of differentially expressed genes and gene ontology, Chlorella sp. ABC-001 exhibited the development of chloroplast organelles during the early exponential phase under high CO2 conditions, resulting in improved CO2 fixation and enhanced photosynthesis. Cobalamin-independent methionine synthase expression was also significantly elevated during the early growth stage, likely contributing to the methionine supply required for various metabolic activities and active proliferation. Conversely, the cells showed sustained repression of carbonic anhydrase and ferredoxin hydrogenase, involved in the carbon concentrating mechanism, throughout the cultivation period under high CO2 conditions. This study also delved into the transcriptomic profiles in the Calvin cycle, nitrogen reductase, and lipid synthesis. Particularly, Chlorella sp. ABC-001 showed high expression levels of genes involved in lipid synthesis, such as glycerol-3-phosphate dehydrogenase and phospholipid-diacylglycerol acyltransferase. These findings suggest potential targets for metabolic engineering aimed at enhancing lipid production in microalgae. CONCLUSIONS We expect that our findings will help understand the carbon concentrating mechanism, photosynthesis, nitrogen assimilation, and lipid accumulation metabolisms of green algae according to CO2 concentrations. This study also provides insights into systems metabolic engineering of microalgae for improved performance in the future.
Collapse
Affiliation(s)
- Hyun Gi Koh
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jun Muk Cho
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Seungjib Jeon
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Yong Keun Chang
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Bongsoo Lee
- Department of Microbial Biotechnology, College of Science and Technology, Mokwon University, 88 Doanbuk-ro, Seo-gu, Daejeon, 35349, Republic of Korea.
| | - Nam Kyu Kang
- Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin, 17104, Republic of Korea.
| |
Collapse
|
6
|
Sun H, Gao Z, Zhang L, Wang X, Gao M, Wang Q. A comprehensive review on microbial lipid production from wastes: research updates and tendencies. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:79654-79675. [PMID: 37328718 DOI: 10.1007/s11356-023-28123-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 06/01/2023] [Indexed: 06/18/2023]
Abstract
Microbial lipids have recently attracted attention as an intriguing alternative for the biodiesel and oleochemical industries to achieve sustainable energy generation. However, large-scale lipid production remains limited due to the high processing costs. As multiple variables affect lipid synthesis, an up-to-date overview that will benefit researchers studying microbial lipids is necessary. In this review, the most studied keywords from bibliometric studies are first reviewed. Based on the results, the hot topics in the field were identified to be associated with microbiology studies that aim to enhance lipid synthesis and reduce production costs, focusing on the biological and metabolic engineering involved. The research updates and tendencies of microbial lipids were then analyzed in depth. In particular, feedstock and associated microbes, as well as feedstock and corresponding products, were analyzed in detail. Strategies for lipid biomass enhancement were also discussed, including feedstock adoption, value-added product synthesis, selection of oleaginous microbes, cultivation mode optimization, and metabolic engineering strategies. Finally, the environmental implications of microbial lipid production and possible research directions were presented.
Collapse
Affiliation(s)
- Haishu Sun
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
- Shunde Innovation School, University of Science and Technology Beijing, Foshan, 528399, China
| | - Zhen Gao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Lirong Zhang
- Tianjin College, University of Science and Technology, Beijing, Tianjin, 301811, China
| | - Xiaona Wang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
- Shunde Innovation School, University of Science and Technology Beijing, Foshan, 528399, China.
| | - Ming Gao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Qunhui Wang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
- Tianjin College, University of Science and Technology, Beijing, Tianjin, 301811, China
| |
Collapse
|
7
|
Yan B, Chang C, Gu Y, Zheng N, Fang Y, Zhang M, Wang G, Zhang L. Genome-Wide Identification, Classification, and Expression Analyses of the CsDGAT Gene Family in Cannabis sativa L. and Their Response to Cold Treatment. Int J Mol Sci 2023; 24:ijms24044078. [PMID: 36835488 PMCID: PMC9963917 DOI: 10.3390/ijms24044078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/03/2023] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Hempseed is a nutrient-rich natural resource, and high levels of hempseed oil accumulate within hemp seeds, consisting primarily of different triglycerides. Members of the diacylglycerol acyltransferase (DGAT) enzyme family play critical roles in catalyzing triacylglycerol biosynthesis in plants, often governing the rate-limiting step in this process. As such, this study was designed to characterize the Cannabis sativa DGAT (CsDGAT) gene family in detail. Genomic analyses of the C. sativa revealed 10 candidate DGAT genes that were classified into four families (DGAT1, DGAT2, DGAT3, WS/DGAT) based on the features of different isoforms. Members of the CsDGAT family were found to be associated with large numbers of cis-acting promoter elements, including plant response elements, plant hormone response elements, light response elements, and stress response elements, suggesting roles for these genes in key processes such as development, environmental adaptation, and abiotic stress responses. Profiling of these genes in various tissues and varieties revealed varying spatial patterns of CsDGAT expression dynamics and differences in expression among C. sativa varieties, suggesting that the members of this gene family likely play distinct functional regulatory functions CsDGAT genes were upregulated in response to cold stress, and significant differences in the mode of regulation were observed when comparing roots and leaves, indicating that CsDGAT genes may play positive roles as regulators of cold responses in hemp while also playing distinct roles in shaping the responses of different parts of hemp seedlings to cold exposure. These data provide a robust basis for further functional studies of this gene family, supporting future efforts to screen the significance of CsDGAT candidate genes to validate their functions to improve hempseed oil composition.
Collapse
Affiliation(s)
- Bowei Yan
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Chuanyi Chang
- Harbin Academy of Agricultural Science, Harbin 150028, China
| | - Yingnan Gu
- Remote Sensing Technique Center, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Nan Zheng
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Yuyan Fang
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Ming Zhang
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Guijiang Wang
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
- Correspondence: (G.W.); (L.Z.)
| | - Liguo Zhang
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
- Correspondence: (G.W.); (L.Z.)
| |
Collapse
|
8
|
Chen G, Harwood JL, Lemieux MJ, Stone SJ, Weselake RJ. Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control. Prog Lipid Res 2022; 88:101181. [PMID: 35820474 DOI: 10.1016/j.plipres.2022.101181] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 12/15/2022]
Abstract
Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.
Collapse
Affiliation(s)
- Guanqun Chen
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Membrane Protein Disease Research Group, Edmonton T6G 2H7, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| | - Randall J Weselake
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada
| |
Collapse
|
9
|
Domergue F, Miklaszewska M. The production of wax esters in transgenic plants:
towards a sustainable source of bio-lubricants. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2817-2834. [PMID: 35560197 PMCID: PMC9113324 DOI: 10.1093/jxb/erac046] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 02/03/2022] [Indexed: 05/08/2023]
Abstract
Wax esters are high-value compounds used as feedstocks for the production of lubricants, pharmaceuticals, and cosmetics. Currently, they are produced mostly from fossil reserves using chemical synthesis, but this cannot meet increasing demand and has a negative environmental impact. Natural wax esters are also obtained from Simmondsia chinensis (jojoba) but comparably in very low amounts and expensively. Therefore, metabolic engineering of plants, especially of the seed storage lipid metabolism of oil crops, represents an attractive strategy for renewable, sustainable, and environmentally friendly production of wax esters tailored to industrial applications. Utilization of wax ester-synthesizing enzymes with defined specificities and modulation of the acyl-CoA pools by various genetic engineering approaches can lead to obtaining wax esters with desired compositions and properties. However, obtaining high amounts of wax esters is still challenging due to their negative impact on seed germination and yield. In this review, we describe recent progress in establishing non-food-plant platforms for wax ester production and discuss their advantages and limitations as well as future prospects.
Collapse
Affiliation(s)
- Frédéric Domergue
- Univ. Bordeaux, CNRS, LBM, UMR 5200, F-33140 Villenave d’Ornon, France
| | - Magdalena Miklaszewska
- Department of Functional and Evolutionary Ecology, Division of Molecular Systems Biology (MOSYS), Faculty of Life Sciences, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Department of Plant Physiology and Biotechnology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
| |
Collapse
|
10
|
Kang NK, Baek K, Koh HG, Atkinson CA, Ort DR, Jin YS. Microalgal metabolic engineering strategies for the production of fuels and chemicals. BIORESOURCE TECHNOLOGY 2022; 345:126529. [PMID: 34896527 DOI: 10.1016/j.biortech.2021.126529] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Microalgae are promising sustainable resources because of their ability to convert CO2 into biofuels and chemicals directly. However, the industrial production and economic feasibility of microalgal bioproducts are still limited. As such, metabolic engineering approaches have been undertaken to enhance the productivities of microalgal bioproducts. In the last decade, impressive advances in microalgae metabolic engineering have been made by developing genetic engineering tools and multi-omics analysis. This review presents comprehensive microalgal metabolic pathways and metabolic engineering strategies for producing lipids, long chain-polyunsaturated fatty acids, terpenoids, and carotenoids. Additionally, promising metabolic engineering approaches specific to target products are summarized. Finally, this review discusses current challenges and provides future perspectives for the effective production of chemicals and fuels via microalgal metabolic engineering.
Collapse
Affiliation(s)
- Nam Kyu Kang
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Kwangryul Baek
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hyun Gi Koh
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Christine Anne Atkinson
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Donald R Ort
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Global Change and Photosynthesis Research Unit, Agricultural Research Service, United States Department of Agriculture, Urbana, IL, USA; Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Yong-Su Jin
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
| |
Collapse
|
11
|
Zhang Y, Guo X, Yang H, Shi S. The Studies in Constructing Yeast Cell Factories for the Production of Fatty Acid Alkyl Esters. Front Bioeng Biotechnol 2022; 9:799032. [PMID: 35087801 PMCID: PMC8787340 DOI: 10.3389/fbioe.2021.799032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/19/2021] [Indexed: 12/25/2022] Open
Abstract
Fatty acid alkyl esters have broad applications in biofuels, lubricant formulas, paints, coatings, and cosmetics. Traditionally, these esters are mostly produced through unsustainable and energy-intensive processes. In contrast, microbial production of esters from renewable and sustainable feedstocks may provide a promising alternative and has attracted widespread attention in recent years. At present, yeasts are used as ideal hosts for producing such esters, due to their availability for high-density fermentation, resistance to phage infection, and tolerance against toxic inhibitors. Here, we summarize recent development on the biosynthesis of alkyl esters, including fatty acid ethyl esters (FAEEs), fatty acid short-branched chain alkyl esters (FASBEs), and wax esters (WEs) by various yeast cell factories. We focus mainly on the enzyme engineering strategies of critical wax ester synthases, and the pathway engineering strategies employed for the biosynthesis of various ester products. The bottlenecks that limit productivity and their potential solutions are also discussed in this review.
Collapse
Affiliation(s)
- Yang Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China.,CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xiao Guo
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Huaiyi Yang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Shuobo Shi
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| |
Collapse
|
12
|
Ma H, Zheng J, Li Y, Zhao L, Zou S, Hu Q, Han D. A Novel Bifunctional Wax Ester Synthase Involved in Early Triacylglycerol Accumulation in Unicellular Green Microalga Haematococcus pluvialis Under High Light Stress. Front Bioeng Biotechnol 2022; 9:794714. [PMID: 35111735 PMCID: PMC8802113 DOI: 10.3389/fbioe.2021.794714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/30/2021] [Indexed: 11/20/2022] Open
Abstract
The bulk of neutral lipids, including astaxanthin esters and triacylglycerols (TAGs), are accumulated in the green microalga Haematococcus pluvialis under high light (HL) stress. In this study, a novel bifunctional wax ester synthase (WS) gene was cloned from H. pluvialis upon HL stress. The overexpression of HpWS restored the biosynthesis of wax esters and TAGs in neutral lipid-deficient yeast mutant Saccharomyces cerevisiae H1246 fed with C18 alcohol and C18:1/C18:3 fatty acids, respectively. Under HL stress, HpWS was substantially upregulated at the transcript level, prior to that of the type I diacylglycerol:acyl-CoA acyltransferase encoding gene (HpDGAT1). HpDGAT1 is the major TAG synthase in H. pluvialis. In addition, the application of xanthohumol (a DGAT1/2 inhibitor) in the H. pluvialis cells did not completely eliminate the TAG biosynthesis under HL stress at 24 h. These results indicated that HpWS may contribute to the accumulation of TAGs in H. pluvialis at the early stage under HL stress. In addition, the overexpression of HpWS in Chlamydomonas reinhardtii bkt5, which is engineered to produce free astaxanthin, enhanced the production of TAGs and astaxanthin. Our findings broaden the understanding of TAG biosynthesis in microalgae and provide a new molecular target for genetic manipulation in biotechnological applications.
Collapse
Affiliation(s)
- Haiyan Ma
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- *Correspondence: Haiyan Ma,
| | - Jie Zheng
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yanhua Li
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Liang Zhao
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Song Zou
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Danxiang Han
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| |
Collapse
|
13
|
Metabolic engineering of the oleaginous alga Nannochloropsis for enriching eicosapentaenoic acid in triacylglycerol by combined pulling and pushing strategies. Metab Eng 2021; 69:163-174. [PMID: 34864212 DOI: 10.1016/j.ymben.2021.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 11/20/2021] [Accepted: 11/30/2021] [Indexed: 11/23/2022]
Abstract
The marine alga Nannochloropsis oceanica has been considered as a promising photosynthetic cell factory for synthesizing eicosapentaenoic acid (EPA), yet the accumulation of EPA in triacylglycerol (TAG) is restricted to an extreme low level. Poor channeling of EPA to TAG was observed in N. oceanica under TAG induction conditions, likely due to the weak activity of endogenous diacylglycerol acyltransferases (DGATs) on EPA-CoA. Screening over thirty algal DGATs revealed potent enzymes acting on EPA-CoA. Whilst overexpressing endogenous DGATs had no or slight effect on EPA abundance in TAG, introducing selected DGATs with strong activity on EPA-CoA, particularly the Chlamydomonas-derived CrDGTT1, which resided at the outermost membrane of the chloroplast and provided a strong pulling power to divert EPA to TAG for storage and protection, led to drastic increases in EPA abundance in TAG and TAG-derived EPA level in N. oceanica. They were further promoted by additional overexpression of an elongase gene involved in EPA biosynthesis, reaching 5.9- and 12.3-fold greater than the control strain, respectively. Our results together demonstrate the concept of applying combined pulling and pushing strategies to enrich EPA in algal TAG and provide clues for the enrichment of other desired fatty acids in TAG as well.
Collapse
|
14
|
Blasio M, Balzano S. Fatty Acids Derivatives From Eukaryotic Microalgae, Pathways and Potential Applications. Front Microbiol 2021; 12:718933. [PMID: 34659147 PMCID: PMC8511707 DOI: 10.3389/fmicb.2021.718933] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 08/24/2021] [Indexed: 11/13/2022] Open
Abstract
The exploitation of petrochemical hydrocarbons is compromising ecosystem and human health and biotechnological research is increasingly focusing on sustainable materials from plants and, to a lesser extent, microalgae. Fatty acid derivatives include, among others, oxylipins, hydroxy fatty acids, diols, alkenones, and wax esters. They can occur as storage lipids or cell wall components and possess, in some cases, striking cosmeceutical, pharmaceutical, and nutraceutical properties. In addition, long chain (>20) fatty acid derivatives mostly contain highly reduced methylenic carbons and exhibit a combustion enthalpy higher than that of C14–20 fatty acids, being potentially suitable as biofuel candidates. Finally, being the building blocks of cell wall components, some fatty acid derivatives might also be used as starters for the industrial synthesis of different polymers. Within this context, microalgae can be a promising source of fatty acid derivatives and, in contrast with terrestrial plants, do not require arable land neither clean water for their growth. Microalgal mass culturing for the extraction and the exploitation of fatty acid derivatives, along with products that are relevant in nutraceutics (e.g., polyunsaturated fatty acids), might contribute in increasing the viability of microalgal biotechnologies. This review explores fatty acids derivatives from microalgae with applications in the field of renewable energies, biomaterials and pharmaceuticals. Nannochloropsis spp. (Eustigmatophyceae, Heterokontophyta) are particularly interesting for biotechnological applications since they grow at faster rates than many other species and possess hydroxy fatty acids and aliphatic cell wall polymers.
Collapse
Affiliation(s)
- Martina Blasio
- Department of Marine Biotechnologies, Stazione Zoologica Anton Dohrn Napoli (SZN), Naples, Italy
| | - Sergio Balzano
- Department of Marine Biotechnologies, Stazione Zoologica Anton Dohrn Napoli (SZN), Naples, Italy.,Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg (Texel), Netherlands
| |
Collapse
|
15
|
Villanova V, Spetea C. Mixotrophy in diatoms: Molecular mechanism and industrial potential. PHYSIOLOGIA PLANTARUM 2021; 173:603-611. [PMID: 34076276 DOI: 10.1111/ppl.13471] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 05/20/2021] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Diatoms are microalgae well known for their high variability and high primary productivity, being responsible for about 20% of the annual global carbon fixation. Moreover, they are interesting as potential feedstocks for the production of biofuels and high-value lipids and carotenoids. Diatoms exhibit trophic flexibility and, under certain conditions, they can grow mixotrophically by combing photosynthesis and respiration. So far, only a few species of diatoms have been tested for their mixotrophic metabolism; in some cases, they produced more biomass and with higher lipid content when grown under this condition. Phaeodactylum tricornutum is the most studied diatom species for its mixotrophic metabolism due to available genome sequence and molecular tools. However, studies in additional species are needed to better understand the conservation of this process in diatoms and its potential in industrial applications. Here, we describe the photosynthetic and respiratory pathways involved in mixotrophy and provide an overview of the trophic variability in diatoms. This review also highlights promising areas of industrial applications for diatoms when cultivated under mixotrophy.
Collapse
Affiliation(s)
- Valeria Villanova
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Cornelia Spetea
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
16
|
Lu X, Cui Y, Chen Y, Xiao Y, Song X, Gao F, Xiang Y, Hou C, Wang J, Gan Q, Zheng X, Lu Y. Sustainable development of microalgal biotechnology in coastal zone for aquaculture and food. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 780:146369. [PMID: 33773342 DOI: 10.1016/j.scitotenv.2021.146369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/05/2021] [Accepted: 03/05/2021] [Indexed: 06/12/2023]
Abstract
Region-specific Research and Development (R&D) of microalga-derived product systems are crucial if "biotech's green gold" is to be explored in a rational and economically viable way. Coastal zones, particularly the locations around the equator, are typically considered to be optimum cultivation sites due to stable annual temperature, light, and ready availability of seawater. However, a 'cradle-to-grave' assessment of the development of microalgal biotechnology in these areas, not only under the laboratory conditions, but also in the fields has not yet been demonstrated. In this study, to evaluate the viability of microalga-derived multi-product technology, we showed the development of microalgal biotechnology in coastal zones for aquaculture and food. By creating and screening a (sub)tropical microalgal collection, a Chlorella strain MEM25 with a robust growth in a wide range of salinities, temperatures, and light intensities was identified. Evaluation of the economic viability and performance of different scale cultivation system designs (500 L and 5000 L closed photobioreactors and 60,000 L open race ponds, ORPs) at coastal zones under geographically specific conditions showed the stable and robust characteristics of MEM25 across different production system designs and various spatial and temporal scales. It produces high amounts of proteins and polyunsaturated fatty acids (PUFAs) in various conditions. Feeding experiments reveal the nutritional merits of MEM25 as food additives where PUFAs and essential amino acids are enriched and the algal diet improves consumers' growth. Economic evaluation highlights an appreciable profitability of MEM25 production as human or animal food using ORP systems. Therefore, despite the pros and cons, sound opportunities exist for the development of market-ready multiple-product systems by employing region-specific R&D strategies for microalgal biotechnology.
Collapse
Affiliation(s)
- Xiangning Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China
| | - Yulin Cui
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, Shandong Province, China
| | - Yuting Chen
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China
| | - Yupeng Xiao
- Hainan GreenEnergy Microalgal Biotechnology Co., Ltd, Danzhou 571700, Hainan Province, China
| | - Xiaojin Song
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China
| | - Fengzheng Gao
- Bioprocess Engineering, Wageningen University and Research, 6708PB Wageningen, Netherlands
| | - Yun Xiang
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China
| | - Congcong Hou
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, Fujian Province, China
| | - Jun Wang
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China
| | - Qinhua Gan
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China
| | - Xing Zheng
- Hainan GreenEnergy Microalgal Biotechnology Co., Ltd, Danzhou 571700, Hainan Province, China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228, China.
| |
Collapse
|
17
|
Xu Y, Pan X, Lu J, Wang J, Shan Q, Stout J, Chen G. Evolutionary and biochemical characterization of a Chromochloris zofingiensis MBOAT with wax synthase and diacylglycerol acyltransferase activity. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5584-5598. [PMID: 34037747 DOI: 10.1093/jxb/erab236] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
Wax synthase (WS) catalyzes the last step in wax ester biosynthesis in green plants. Two unrelated sub-families of WS, including the bifunctional acyltransferase and plant-like WS have been reported, but the latter is largely uncharacterized in microalgae. Here, we functionally characterized a putative plant-like WS (CzWS1) from the emerging model green microalga Chromochloris zofingiensis. Our results showed that plant-like WS evolved under different selection constraints in plants and microalgae, with positive selection likely contributing to functional divergence. Unlike jojoba with high amounts of wax ester in seeds and a highly active WS enzyme, C. zofingiensis has no detectable wax ester but a high abundance of WS transcripts. Co-expression analysis showed that C. zofingiensis WS has different expression correlation with lipid biosynthetic genes from jojoba, and may have a divergent function. In vitro characterization indicated that CzWS1 had diacylglycerol acyltransferase activity along with WS activity, and overexpression of CzWS1 in yeast and Chlamydomonas reinhardtii affected triacylglycerol accumulation. Moreover, biochemical and bioinformatic analyses revealed the relevance of the C-terminal region of CzWS1 in enzyme function. Taken together, our results indicated a functional divergence of plant-like WS in plants and microalgae, and the importance of its C-terminal region in specialization of enzyme function.
Collapse
Affiliation(s)
- Yang Xu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Xue Pan
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Junhao Lu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Juli Wang
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Qiyuan Shan
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jake Stout
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Guanqun Chen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
18
|
Lu Y, Gu X, Lin H, Melis A. Engineering microalgae: transition from empirical design to programmable cells. Crit Rev Biotechnol 2021; 41:1233-1256. [PMID: 34130561 DOI: 10.1080/07388551.2021.1917507] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Domesticated microalgae hold great promise for the sustainable provision of various bioresources for human domestic and industrial consumption. Efforts to exploit their potential are far from being fully realized due to limitations in the know-how of microalgal engineering. The associated technologies are not as well developed as those for heterotrophic microbes, cyanobacteria, and plants. However, recent studies on microalgal metabolic engineering, genome editing, and synthetic biology have immensely helped to enhance transformation efficiencies and are bringing new insights into this field. Therefore, this article, summarizes recent developments in microalgal biotechnology and examines the prospects for generating specialty and commodity products through the processes of metabolic engineering and synthetic biology. After a brief examination of empirical engineering methods and vector design, this article focuses on quantitative transformation cassette design, elaborates on target editing methods and emerging digital design of algal cellular metabolism to arrive at high yields of valuable products. These advances have enabled a transition of manners in microalgal engineering from single-gene and enzyme-based metabolic engineering to systems-level precision engineering, from cells created with genetically modified (GM) tags to that without GM tags, and ultimately from proof of concept to tangible industrial applications. Finally, future trends are proposed in microalgal engineering, aiming to establish individualized transformation systems in newly identified species for strain-specific specialty and commodity products, while developing sophisticated universal toolkits in model algal species.
Collapse
Affiliation(s)
- Yandu Lu
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, China.,Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Xinping Gu
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, China
| | - Hanzhi Lin
- Institute of Marine & Environmental Technology, Center for Environmental Science, University of Maryland, College Park, MD, USA
| | - Anastasios Melis
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| |
Collapse
|
19
|
Chen H, Wang Q. Regulatory mechanisms of lipid biosynthesis in microalgae. Biol Rev Camb Philos Soc 2021; 96:2373-2391. [PMID: 34101323 DOI: 10.1111/brv.12759] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 02/01/2023]
Abstract
Microalgal lipids are highly promising feedstocks for biofuel production. Microalgal lipids, especially triacylglycerol, and practical applications of these compounds have received increasing attention in recent years. For the commercial use of microalgal lipids to be feasible, many fundamental biological questions must be addressed based on detailed studies of algal biology, including how lipid biosynthesis occurs and is regulated. Here, we review the current understanding of microalgal lipid biosynthesis, with a focus on the underlying regulatory mechanisms. We also present possible solutions for overcoming various obstacles to understanding the basic biology of microalgal lipid biosynthesis and the practical application of microalgae-based lipids. This review will provide a theoretical reference for both algal researchers and decision makers regarding the future directions of microalgal research, particularly pertaining to microalgal-based lipid biosynthesis.
Collapse
Affiliation(s)
- Hui Chen
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| |
Collapse
|
20
|
Zhang Y, Ye Y, Bai F, Liu J. The oleaginous astaxanthin-producing alga Chromochloris zofingiensis: potential from production to an emerging model for studying lipid metabolism and carotenogenesis. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:119. [PMID: 33992124 PMCID: PMC8126118 DOI: 10.1186/s13068-021-01969-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/07/2021] [Indexed: 05/05/2023]
Abstract
The algal lipids-based biodiesel, albeit having advantages over plant oils, still remains high in the production cost. Co-production of value-added products with lipids has the potential to add benefits and is thus believed to be a promising strategy to improve the production economics of algal biodiesel. Chromochloris zofingiensis, a unicellular green alga, has been considered as a promising feedstock for biodiesel production because of its robust growth and ability of accumulating high levels of triacylglycerol under multiple trophic conditions. This alga is also able to synthesize high-value keto-carotenoids and has been cited as a candidate producer of astaxanthin, the strongest antioxidant found in nature. The concurrent accumulation of triacylglycerol and astaxanthin enables C. zofingiensis an ideal cell factory for integrated production of the two compounds and has potential to improve algae-based production economics. Furthermore, with the advent of chromosome-level whole genome sequence and genetic tools, C. zofingiensis becomes an emerging model for studying lipid metabolism and carotenogenesis. In this review, we summarize recent progress on the production of triacylglycerol and astaxanthin by C. zofingiensis. We also update our understanding in the distinctive molecular mechanisms underlying lipid metabolism and carotenogenesis, with an emphasis on triacylglycerol and astaxanthin biosynthesis and crosstalk between the two pathways. Furthermore, strategies for trait improvements are discussed regarding triacylglycerol and astaxanthin synthesis in C. zofingiensis.
Collapse
Affiliation(s)
- Yu Zhang
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Ying Ye
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Fan Bai
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Jin Liu
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China.
| |
Collapse
|
21
|
Guéguen N, Le Moigne D, Amato A, Salvaing J, Maréchal E. Lipid Droplets in Unicellular Photosynthetic Stramenopiles. FRONTIERS IN PLANT SCIENCE 2021; 12:639276. [PMID: 33968100 PMCID: PMC8100218 DOI: 10.3389/fpls.2021.639276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
The Heterokonta or Stramenopile phylum comprises clades of unicellular photosynthetic species, which are promising for a broad range of biotechnological applications, based on their capacity to capture atmospheric CO2 via photosynthesis and produce biomolecules of interest. These molecules include triacylglycerol (TAG) loaded inside specific cytosolic bodies, called the lipid droplets (LDs). Understanding TAG production and LD biogenesis and function in photosynthetic stramenopiles is therefore essential, and is mostly based on the study of a few emerging models, such as the pennate diatom Phaeodactylum tricornutum and eustigmatophytes, such as Nannochloropsis and Microchloropsis species. The biogenesis of cytosolic LD usually occurs at the level of the endoplasmic reticulum. However, stramenopile cells contain a complex plastid deriving from a secondary endosymbiosis, limited by four membranes, the outermost one being connected to the endomembrane system. Recent cell imaging and proteomic studies suggest that at least some cytosolic LDs might be associated to the surface of the complex plastid, via still uncharacterized contact sites. The carbon length and number of double bonds of the acyl groups contained in the TAG molecules depend on their origin. De novo synthesis produces long-chain saturated or monounsaturated fatty acids (SFA, MUFA), whereas subsequent maturation processes lead to very long-chain polyunsaturated FA (VLC-PUFA). TAG composition in SFA, MUFA, and VLC-PUFA reflects therefore the metabolic context that gave rise to the formation of the LD, either via an early partitioning of carbon following FA de novo synthesis and/or a recycling of FA from membrane lipids, e.g., plastid galactolipids or endomembrane phosphor- or betaine lipids. In this review, we address the relationship between cytosolic LDs and the complex membrane compartmentalization within stramenopile cells, the metabolic routes leading to TAG accumulation, and the physiological conditions that trigger LD production, in response to various environmental factors.
Collapse
|
22
|
Rani A, Saini KC, Bast F, Mehariya S, Bhatia SK, Lavecchia R, Zuorro A. Microorganisms: A Potential Source of Bioactive Molecules for Antioxidant Applications. Molecules 2021; 26:molecules26041142. [PMID: 33672774 PMCID: PMC7924645 DOI: 10.3390/molecules26041142] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/08/2021] [Accepted: 02/16/2021] [Indexed: 12/17/2022] Open
Abstract
Oxidative stress originates from an elevated intracellular level of free oxygen radicals that cause lipid peroxidation, protein denaturation, DNA hydroxylation, and apoptosis, ultimately impairing cell viability. Antioxidants scavenge free radicals and reduce oxidative stress, which further helps to prevent cellular damage. Medicinal plants, fruits, and spices are the primary sources of antioxidants from time immemorial. In contrast to plants, microorganisms can be used as a source of antioxidants with the advantage of fast growth under controlled conditions. Further, microbe-based antioxidants are nontoxic, noncarcinogenic, and biodegradable as compared to synthetic antioxidants. The present review aims to summarize the current state of the research on the antioxidant activity of microorganisms including actinomycetes, bacteria, fungi, protozoa, microalgae, and yeast, which produce a variety of antioxidant compounds, i.e., carotenoids, polyphenols, vitamins, and sterol, etc. Special emphasis is given to the mechanisms and signaling pathways followed by antioxidants to scavenge Reactive Oxygen Species (ROS), especially for those antioxidant compounds that have been scarcely investigated so far.
Collapse
Affiliation(s)
- Alka Rani
- Department of Botany, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab 151401, India; (A.R.); (K.C.S.); (F.B.)
| | - Khem Chand Saini
- Department of Botany, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab 151401, India; (A.R.); (K.C.S.); (F.B.)
| | - Felix Bast
- Department of Botany, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab 151401, India; (A.R.); (K.C.S.); (F.B.)
| | - Sanjeet Mehariya
- Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, 00184 Rome, Italy;
- Correspondence: (S.M.); (A.Z.); Tel.: +39-347-494-0910 (S.M.); +39-06-4458-5598 (A.Z.)
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 05029, Korea;
| | - Roberto Lavecchia
- Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, 00184 Rome, Italy;
| | - Antonio Zuorro
- Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, 00184 Rome, Italy;
- Correspondence: (S.M.); (A.Z.); Tel.: +39-347-494-0910 (S.M.); +39-06-4458-5598 (A.Z.)
| |
Collapse
|
23
|
Cui H, Zhao C, Xu W, Zhang H, Hang W, Zhu X, Ji C, Xue J, Zhang C, Li R. Characterization of type-2 diacylglycerol acyltransferases in Haematococcus lacustris reveals their functions and engineering potential in triacylglycerol biosynthesis. BMC PLANT BIOLOGY 2021; 21:20. [PMID: 33407140 PMCID: PMC7788937 DOI: 10.1186/s12870-020-02794-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 12/09/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND Haematococcus lacustris is an ideal source of astaxanthin (AST), which is stored in oil bodies containing esterified AST (EAST) and triacylglycerol (TAG). Diacylglycerol acyltransferases (DGATs) catalyze the last step of acyl-CoA-dependent TAG biosynthesis and are also considered as crucial enzymes involved in EAST biosynthesis in H. lacustris. Previous studies have identified four putative DGAT2-encoding genes in H. lacustris, and only HpDGAT2D allowed the recovery of TAG biosynthesis, but the engineering potential of HpDGAT2s in TAG biosynthesis remains ambiguous. RESULTS Five putative DGAT2 genes (HpDGAT2A, HpDGAT2B, HpDGAT2C, HpDGAT2D, and HpDGAT2E) were identified in H. lacustris. Transcription analysis showed that the expression levels of the HpDGAT2A, HpDGAT2D, and HpDGAT2E genes markedly increased under high light and nitrogen deficient conditions with distinct patterns, which led to significant TAG and EAST accumulation. Functional complementation demonstrated that HpDGAT2A, HpDGAT2B, HpDGAT2D, and HpDGAT2E had the capacity to restore TAG synthesis in a TAG-deficient yeast strain (H1246) showing a large difference in enzymatic activity. Fatty acid (FA) profile assays revealed that HpDGAT2A, HpDGAT2D, and HpDGAT2E, but not HpDGAT2B, preferred monounsaturated fatty acyl-CoAs (MUFAs) for TAG synthesis in yeast cells, and showed a preference for polyunsaturated fatty acyl-CoAs (PUFAs) based on their feeding strategy. The heterologous expression of HpDGAT2D in Arabidopsis thaliana and Chlamydomonas reinhardtii significantly increased the TAG content and obviously promoted the MUFAs and PUFAs contents. CONCLUSIONS Our study represents systematic work on the characterization of HpDGAT2s by integrating expression patterns, AST/TAG accumulation, functional complementation, and heterologous expression in yeast, plants, and algae. These results (1) update the gene models of HpDGAT2s, (2) prove the TAG biosynthesis capacity of HpDGAT2s, (3) show the strong preference for MUFAs and PUFAs, and (4) offer target genes to modulate TAG biosynthesis by using genetic engineering methods.
Collapse
Affiliation(s)
- Hongli Cui
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Chunchao Zhao
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Wenxin Xu
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Hongjiang Zhang
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Wei Hang
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Xiaoli Zhu
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Chunli Ji
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Jinai Xue
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Chunhui Zhang
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| | - Runzhi Li
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801 Shanxi China
| |
Collapse
|
24
|
Cui H, Xu W, Zhu X, Zhao C, Cui Y, Ji C, Zhang C, Xue J, Qin S, Jia X, Li R. Characterization of a Haematococcus pluvialis Diacylglycerol Acyltransferase 1 and Its Potential in Unsaturated Fatty Acid-Rich Triacylglycerol Production. FRONTIERS IN PLANT SCIENCE 2021; 12:771300. [PMID: 34950166 PMCID: PMC8688921 DOI: 10.3389/fpls.2021.771300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 11/08/2021] [Indexed: 05/17/2023]
Abstract
The unicellular green alga Haematococcus pluvialis has been recognized as an industry strain to produce simultaneously esterified astaxanthin (EAST) and triacylglycerol (TAG) under stress induction. It is necessary to identify the key enzymes involving in synergistic accumulation of EAST and TAG in H. pluvialis. In this study, a novel diacylglycerol acyltransferase 1 was systematically characterized by in vivo and in silico assays. The upregulated expression of HpDGAT1 gene was positively associated with the significant increase of TAG and EAST contents under stress conditions. Functional complementation by overexpressing HpDGAT1 in a TAG-deficient yeast strain H1246 revealed that HpDGAT1 could restore TAG biosynthesis and exhibited a high substrate preference for monounsaturated fatty acyl-CoAs (MUFAs) and polyunsaturated fatty acyl-CoAs (PUFAs). Notably, heterogeneous expression of HpDGAT1 in Chlamydomonas reinhardtii and Arabidopsis thaliana resulted in a significant enhancement of total oils and concurrently a high accumulation of MUFAs- and PUFAs-rich TAGs. Furthermore, molecular docking analysis indicated that HpDGAT1 contained AST-binding sites. These findings evidence a possible dual-function role for HpDGAT1 involving in TAG and EAST synthesis, demonstrating that it is a potential target gene to enrich AST accumulation in this alga and to design oil production in both commercial algae and oil crops.
Collapse
Affiliation(s)
- Hongli Cui
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Wenxin Xu
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Xiaoli Zhu
- College of Plant Protection, Shanxi Agricultural University, Taigu, China
| | - Chunchao Zhao
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Yulin Cui
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Chunli Ji
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Chunhui Zhang
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Jinai Xue
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
| | - Song Qin
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Xiaoyun Jia
- College of Life Sciences, Shanxi Agricultural University, Taigu, China
| | - Runzhi Li
- College of Agriculture, Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, China
- *Correspondence: Runzhi Li,
| |
Collapse
|
25
|
Choi KR, Jiao S, Lee SY. Metabolic engineering strategies toward production of biofuels. Curr Opin Chem Biol 2020; 59:1-14. [DOI: 10.1016/j.cbpa.2020.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 10/24/2022]
|
26
|
Lu Y, Jiang J, Zhao H, Han X, Xiang Y, Zhou W. Clade-Specific Sterol Metabolites in Dinoflagellate Endosymbionts Are Associated with Coral Bleaching in Response to Environmental Cues. mSystems 2020; 5:e00765-20. [PMID: 32994291 PMCID: PMC7527140 DOI: 10.1128/msystems.00765-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 08/18/2020] [Indexed: 11/20/2022] Open
Abstract
Cnidarians cannot synthesize sterols (which play essential roles in growth and development) de novo but often use sterols acquired from endosymbiotic dinoflagellates. While sterol availability can impact the mutualistic interaction between coral host and algal symbiont, the biosynthetic pathways (in the dinoflagellate endosymbionts) and functional roles of sterols in these symbioses are poorly understood. In this study, we found that itraconazole, which perturbs sterol metabolism by inhibiting the sterol 14-demethylase CYP51 in dinoflagellates, induces bleaching of the anemone Heteractis crispa and that bleaching perturbs sterol metabolism of the dinoflagellate. While Symbiodiniaceae have clade-specific sterol metabolites, they share features of the common sterol biosynthetic pathway but with distinct architecture and substrate specificity features of participating enzymes. Tracking sterol profiles and transcripts of enzymes involved in sterol biosynthesis across time in response to different environmental cues revealed similarities and idiosyncratic features of sterol synthesis in the endosymbiont Breviolum minutum Exposure of algal cultures to high levels of light, heat, and acidification led to alterations in sterol synthesis, including blocks through downregulation of squalene synthase transcript levels accompanied by marked growth reductions.IMPORTANCE These results indicate that sterol metabolites in Symbiodiniaceae are clade specific, that their biosynthetic pathways share architectural and substrate specificity features with those of animals and plants, and that environmental stress-specific perturbation of sterol biosynthesis in dinoflagellates can impair a key mutualistic partnership for healthy reefs.
Collapse
Affiliation(s)
- Yandu Lu
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, Hainan, China
| | - Jiaoyun Jiang
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, Hainan, China
- College of Life Sciences, Guangxi Normal University, Guilin, Guangxi, China
| | - Hongwei Zhao
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, Hainan, China
| | - Xiao Han
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, Hainan, China
| | - Yun Xiang
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, Hainan, China
| | - Wenxu Zhou
- Shandong Rongchen Pharmaceuticals Inc., Qingdao, China
| |
Collapse
|
27
|
Han X, Song X, Li F, Lu Y. Improving lipid productivity by engineering a control-knob gene in the oleaginous microalga Nannochloropsis oceanica. Metab Eng Commun 2020; 11:e00142. [PMID: 32995270 PMCID: PMC7516279 DOI: 10.1016/j.mec.2020.e00142] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/06/2020] [Accepted: 08/19/2020] [Indexed: 01/08/2023] Open
Abstract
Nannochloropsis spp. are promising industrial microalgae for scalable oil production and the lipid production can be boosted by nutrient starvation and high irradiance. However, these stimuli halt growth, thereby decreasing overall productivity. In this study, we created transgenic N. oceanica where AtDXS gene encoding 1-deoxy-D-xylulose 5-phosphate synthase (DXS) derived from Arabidopsis thaliana was overexpressed in vivo. Compared with the wild type (WT), engineered Nannochloropsis showed a higher CO2 absorption capacity and produced more biomass, lipids, and carbohydrates with more robust growth in either preferred conditions or various stressed conditions (low light, high light, nitrogen starvation, and trace element depletion). Specifically, relative to the WT, lipid production increased by ~68.6% in nitrogen depletion (~1.08 g L−1) and ~110.6% in high light (~1.15 g L−1) in the transgenic strains. As for neutral lipid (triacylglycerol, TAG), the engineered strains produced ~93.2% more in nitrogen depletion (~0.77 g L−1) and ~148.6% more in high light (~0.80 g L−1) than the WT. These values exceed available records in engineered industrial microalgae. Therefore, engineering control-knob genes could modify multiple biological processes simultaneously and enable efficient carbon partitioning to lipid biosynthesis with elevated biomass productivity. It could be further exploited for simultaneous enhancement of growth property and oil productivity in more industrial microalgae. An oil-rich strain Nannochloropsis AtDXSoe3 was genetically created. AtDXSoe3 produces ~110.6% more total lipids than wild-type stain. AtDXSoe3 produces ~148.6% more neutral lipid than wild-type stain. AtDXSoe3 exceeds documented engineered microalgae in oil production. Crucial algal traits could be improved by engineering a single ‘control knob’ gene.
Collapse
Affiliation(s)
- Xiao Han
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, 570228, Hainan Province, China
| | - Xiaojin Song
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
| | - Falan Li
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, 570228, Hainan Province, China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, 570228, Hainan Province, China
| |
Collapse
|
28
|
Leyland B, Boussiba S, Khozin-Goldberg I. A Review of Diatom Lipid Droplets. BIOLOGY 2020; 9:biology9020038. [PMID: 32098118 PMCID: PMC7168155 DOI: 10.3390/biology9020038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 12/20/2022]
Abstract
The dynamic nutrient availability and photon flux density of diatom habitats necessitate buffering capabilities in order to maintain metabolic homeostasis. This is accomplished by the biosynthesis and turnover of storage lipids, which are sequestered in lipid droplets (LDs). LDs are an organelle conserved among eukaryotes, composed of a neutral lipid core surrounded by a polar lipid monolayer. LDs shield the intracellular environment from the accumulation of hydrophobic compounds and function as a carbon and electron sink. These functions are implemented by interconnections with other intracellular systems, including photosynthesis and autophagy. Since diatom lipid production may be a promising objective for biotechnological exploitation, a deeper understanding of LDs may offer targets for metabolic engineering. In this review, we provide an overview of diatom LD biology and biotechnological potential.
Collapse
|
29
|
Vecchi V, Barera S, Bassi R, Dall’Osto L. Potential and Challenges of Improving Photosynthesis in Algae. PLANTS 2020; 9:plants9010067. [PMID: 31947868 PMCID: PMC7020468 DOI: 10.3390/plants9010067] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/24/2019] [Accepted: 12/30/2019] [Indexed: 11/16/2022]
Abstract
Sunlight energy largely exceeds the energy required by anthropic activities, and therefore its exploitation represents a major target in the field of renewable energies. The interest in the mass cultivation of green microalgae has grown in the last decades, as algal biomass could be employed to cover a significant portion of global energy demand. Advantages of microalgal vs. plant biomass production include higher light-use efficiency, efficient carbon capture and the valorization of marginal lands and wastewaters. Realization of this potential requires a decrease of the current production costs, which can be obtained by increasing the productivity of the most common industrial strains, by the identification of factors limiting biomass yield, and by removing bottlenecks, namely through domestication strategies aimed to fill the gap between the theoretical and real productivity of algal cultures. In particular, the light-to-biomass conversion efficiency represents one of the major constraints for achieving a significant improvement of algal cell lines. This review outlines the molecular events of photosynthesis, which regulate the conversion of light into biomass, and discusses how these can be targeted to enhance productivity through mutagenesis, strain selection or genetic engineering. This review highlights the most recent results in the manipulation of the fundamental mechanisms of algal photosynthesis, which revealed that a significant yield enhancement is feasible. Moreover, metabolic engineering of microalgae, focused upon the development of renewable fuel biorefineries, has also drawn attention and resulted in efforts for enhancing productivity of oil or isoprenoids.
Collapse
Affiliation(s)
| | | | | | - Luca Dall’Osto
- Correspondence: ; Tel.: +39-045-8027806; Fax: +39-045-8027929
| |
Collapse
|
30
|
Mao X, Zhang Y, Wang X, Liu J. Novel insights into salinity-induced lipogenesis and carotenogenesis in the oleaginous astaxanthin-producing alga Chromochloris zofingiensis: a multi-omics study. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:73. [PMID: 32322303 PMCID: PMC7161124 DOI: 10.1186/s13068-020-01714-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 04/09/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND Chromochloris zofingiensis, a freshwater alga capable of synthesizing both triacylglycerol (TAG) and astaxanthin, has been receiving increasing attention as a leading candidate producer. While the mechanism of oleaginousness and/or carotenogenesis has been studied under such induction conditions as nitrogen deprivation, high light and glucose feeding, it remains to be elucidated in response to salt stress, a condition critical for reducing freshwater footprint during algal production processes. RESULTS Firstly, the effect of salt concentrations on growth, lipids and carotenoids was examined for C. zofingiensis, and 0.2 M NaCl demonstrated to be the optimal salt concentration for maximizing both TAG and astaxanthin production. Then, the time-resolved lipid and carotenoid profiles and comparative transcriptomes and metabolomes were generated in response to the optimized salt concentration for congruent analysis. A global response was triggered in C. zofingiensis allowing acclimation to salt stress, including photosynthesis impairment, ROS build-up, protein turnover, starch degradation, and TAG and astaxanthin accumulation. The lipid metabolism involved a set of stimulated biological pathways that contributed to carbon precursors, energy and reductant molecules, pushing and pulling power, and storage sink for TAG accumulation. On the other hand, salt stress suppressed lutein biosynthesis, stimulated astaxanthin biosynthesis (mainly via ketolation), yet had little effect on total carotenoid flux, leading to astaxanthin accumulation at the expense of lutein. Astaxanthin was predominantly esterified and accumulated in a well-coordinated manner with TAG, pointing to the presence of common regulators and potential communication for the two compounds. Furthermore, the comparison between salt stress and nitrogen deprivation conditions revealed distinctions in TAG and astaxanthin biosynthesis as well as critical genes with engineering potential. CONCLUSIONS Our multi-omics data and integrated analysis shed light on the salt acclimation of C. zofingiensis and underlying mechanisms of TAG and astaxanthin biosynthesis, provide engineering implications into future trait improvements, and will benefit the development of this alga for production uses under saline environment, thus reducing the footprint of freshwater.
Collapse
Affiliation(s)
- Xuemei Mao
- 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
| | - Xiaofei Wang
- 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
| |
Collapse
|
31
|
Vingiani GM, De Luca P, Ianora A, Dobson ADW, Lauritano C. Microalgal Enzymes with Biotechnological Applications. Mar Drugs 2019; 17:md17080459. [PMID: 31387272 PMCID: PMC6723882 DOI: 10.3390/md17080459] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/26/2022] Open
Abstract
Enzymes are essential components of biological reactions and play important roles in the scaling and optimization of many industrial processes. Due to the growing commercial demand for new and more efficient enzymes to help further optimize these processes, many studies are now focusing their attention on more renewable and environmentally sustainable sources for the production of these enzymes. Microalgae are very promising from this perspective since they can be cultivated in photobioreactors, allowing the production of high biomass levels in a cost-efficient manner. This is reflected in the increased number of publications in this area, especially in the use of microalgae as a source of novel enzymes. In particular, various microalgal enzymes with different industrial applications (e.g., lipids and biofuel production, healthcare, and bioremediation) have been studied to date, and the modification of enzymatic sequences involved in lipid and carotenoid production has resulted in promising results. However, the entire biosynthetic pathways/systems leading to synthesis of potentially important bioactive compounds have in many cases yet to be fully characterized (e.g., for the synthesis of polyketides). Nonetheless, with recent advances in microalgal genomics and transcriptomic approaches, it is becoming easier to identify sequences encoding targeted enzymes, increasing the likelihood of the identification, heterologous expression, and characterization of these enzymes of interest. This review provides an overview of the state of the art in marine and freshwater microalgal enzymes with potential biotechnological applications and provides future perspectives for this field.
Collapse
Affiliation(s)
- Giorgio Maria Vingiani
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Pasquale De Luca
- Research Infrastructure for Marine Biological Resources Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Adrianna Ianora
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Alan D W Dobson
- School of Microbiology, University College Cork, College Road, T12 YN60 Cork, Ireland
- Environmental Research Institute, University College Cork, Lee Road, T23XE10 Cork, Ireland
| | - Chiara Lauritano
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy.
| |
Collapse
|
32
|
Balzano S, Villanueva L, de Bar M, Sahonero Canavesi DX, Yildiz C, Engelmann JC, Marechal E, Lupette J, Sinninghe Damst� JS, Schouten S. Biosynthesis of Long Chain Alkyl Diols and Long Chain Alkenols in Nannochloropsis spp. (Eustigmatophyceae). PLANT & CELL PHYSIOLOGY 2019; 60:1666-1682. [PMID: 31058972 PMCID: PMC6872974 DOI: 10.1093/pcp/pcz078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 04/26/2019] [Indexed: 05/05/2023]
Abstract
We investigated potential biosynthetic pathways of long chain alkenols (LCAs), long chain alkyl diols (LCDs), and long chain hydroxy fatty acids (LCHFAs) in Nannochloropsis oceanica and Nannochloropsis gaditana, by combining culturing experiments with genomic and transcriptomic analyses. Incubation of Nannochloropsis spp. in the dark for 1 week led to significant increases in the cellular concentrations of LCAs and LCDs in both species. Consistently, 13C-labelled substrate experiments confirmed that both LCA and LCD were actively produced in the dark from C14-18 fatty acids by either condensation or elongation/hydroxylation, although no enzymatic evidence was found for the former pathway. Nannochloropsis spp. did, however, contain (i) multiple polyketide synthases (PKSs) including one type (PKS-Clade II) that might catalyze incomplete fatty acid elongations leading to the formation of 3-OH-fatty acids, (ii) 3-hydroxyacyl dehydratases (HADs), which can possibly form Δ2/Δ3 monounsaturated fatty acids, and (iii) fatty acid elongases (FAEs) that could elongate 3-OH-fatty acids and Δ2/Δ3 monounsaturated fatty acids to longer products. The enzymes responsible for reduction of the long chain fatty acids to LCDs and LCAs are, however, unclear. A putative wax ester synthase/acyl coenzyme A (acyl-CoA): diacylglycerol acyltransferase is likely to be involved in the esterification of LCAs and LCDs in the cell wall. Our data thus provide useful insights in predicting the biosynthetic pathways of LCAs and LCDs in phytoplankton suggesting a key role of FAE and PKS enzymes.
Collapse
Affiliation(s)
- Sergio Balzano
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
- Corresponding author: E-mail, ; Fax, +39 081 7641355. Present address: Stazione Zoologica Anton Dohrn, Istituto Nazionale di Biologia Ecologia e Biotecnologie Marine, Villa Comunale, Napoli, Italy
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Marijke de Bar
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
| | - Diana X Sahonero Canavesi
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
| | - Caglar Yildiz
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
| | - Julia C Engelmann
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
| | - Eric Marechal
- Laboratoire de Physiologie Cellulaire et V�g�tale, Unit� mixte de recherche CNRS, CEA, INRA, Universit� Grenoble Alpes, CEA Grenoble, 17 Avenue des Martyrs, Grenoble, France
| | - Josselin Lupette
- Laboratoire de Physiologie Cellulaire et V�g�tale, Unit� mixte de recherche CNRS, CEA, INRA, Universit� Grenoble Alpes, CEA Grenoble, 17 Avenue des Martyrs, Grenoble, France
- Present address: MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Jaap S Sinninghe Damst�
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Stefan Schouten
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, AB Den Burg, The Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| |
Collapse
|
33
|
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]
|
34
|
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.
Collapse
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
| |
Collapse
|
35
|
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.
Collapse
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
| |
Collapse
|
36
|
Song X, Wang J, Wang Y, Feng Y, Cui Q, Lu Y. Artificial creation of Chlorella pyrenoidosa mutants for economic sustainable food production. BIORESOURCE TECHNOLOGY 2018; 268:340-345. [PMID: 30096641 DOI: 10.1016/j.biortech.2018.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/02/2018] [Accepted: 08/03/2018] [Indexed: 06/08/2023]
Abstract
To improve the economic viability of Chlorella as feedstock for food commodities, a serial of concentrations of low-cost sweet sorghum juice (SSJ), alternative to glucose, were used for the fermentation of Chlorella pyrenoidosa. A high biomass and protein production (8.91 g L-1 biomass and 4.52 g L-1 protein) was revealed with 20% SSJ. To further increase productivity, heavy-ion irradiation-mediated mutagenesis was employed to create mutants where a strain K05, with desired phenotypes (increased biomass and protein production in pilot-scale fermentation), was screened. Compared with the parental strain, the production of biomass, proteins, and chlorophylls of mutant K05 increased by 11.6%, 31.8%, and 7.6%, respectively. Production capacities under industrial scale (two-ton) further pinpoint the stability and scalability of mutant K05. These results suggest that advances in cultivation techniques coupled with artificial strain improvement will further promote microalgae as an attractive platform of functional food.
Collapse
Affiliation(s)
- Xiaojin Song
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China
| | - Jie Wang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
| | - Yanchao Wang
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China
| | - Yingang Feng
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China
| | - Qiu Cui
- Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou 570228, Hainan Province, China.
| |
Collapse
|
37
|
Gan Q, Jiang J, Han X, Wang S, Lu Y. Engineering the Chloroplast Genome of Oleaginous Marine Microalga Nannochloropsis oceanica. FRONTIERS IN PLANT SCIENCE 2018; 9:439. [PMID: 29696028 PMCID: PMC5904192 DOI: 10.3389/fpls.2018.00439] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 03/21/2018] [Indexed: 05/21/2023]
Abstract
Plastid engineering offers an important tool to fill the gap between the technical and the enormous potential of microalgal photosynthetic cell factory. However, to date, few reports on plastid engineering in industrial microalgae have been documented. This is largely due to the small cell sizes and complex cell-wall structures which make these species intractable to current plastid transformation methods (i.e., biolistic transformation and polyethylene glycol-mediated transformation). Here, employing the industrial oleaginous microalga Nannochloropsis oceanica as a model, an electroporation-mediated chloroplast transformation approach was established. Fluorescent microscopy and laser confocal scanning microscopy confirmed the expression of the green fluorescence protein, driven by the endogenous plastid promoter and terminator. Zeocin-resistance selection led to an acquisition of homoplasmic strains of which a stable and site-specific recombination within the chloroplast genome was revealed by sequencing and DNA gel blotting. This demonstration of electroporation-mediated chloroplast transformation opens many doors for plastid genome editing in industrial microalgae, particularly species of which the chloroplasts are recalcitrant to chemical and microparticle bombardment transformation.
Collapse
Affiliation(s)
- Qinhua Gan
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, China
| | - Jiaoyun Jiang
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, China
| | - Xiao Han
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, China
| | - Shifan Wang
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Hainan University, Haikou, China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Hainan University, Haikou, China
- *Correspondence: Yandu Lu
| |
Collapse
|