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Industrial oil-producing microalgae can directly synthesize carbon dioxide and water into high-energy-density oil molecules (triglycerides; TAGs) through photosynthesis. The saturation of the fatty acid carbon chain on the triglyceride determines whether the algal oil is suitable for biodiesel or is suitable as a nutrient. Therefore, saturation is one of the most critical factors determining the quality, use and economic value of algae oil. However, can rational design of algal oil saturation be based on industrial microalgae cells? The International Cooperation Team led by the Single Cell Center of the Institute of Bioenergy and Biotechnology, Chinese Academy of Sciences, including the University of Maryland, Peking University, Institute of Hydrobiology, Chinese Academy of Sciences, etc., through the elucidation and regulation of a series of endogenous type II The division of labor and cooperation mechanism of diacylglycerol acyltransferase (DGAT2) proved that the algal oil saturation of industrial microalgae can be manually customized, and the microalgae cell plant was pushed into the “Customer Oil Quality†(Designer Oil). era. The work was published online at the Molecular Plant on October 27.
Nannochloropsis is a kind of industrial microalgae that can be cultivated on a large scale outdoors in all parts of the world. It has the outstanding advantages of fast growth, strong carbon dioxide tolerance, strong accumulation of oils and fats, and the cultivation of seawater and fresh water. One of the main research models and industrial representative algae in the bioenergy field at home and abroad. Microarcenic algae oil contains both saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA). If the MUFA content is high, the algae oil is suitable as a high-quality liquid fuel to serve the energy market; and if the PUFA (such as EPA, etc.) has a high content, the algal oil is more suitable as a human health product to serve the nutrition and food market. Therefore, if the artificial regulation and even rational design of SFA, MUFA, and PUFA ratios can be realized in the same chassis cell, a highly controllable and flexible switching of algal oil quality, use, and value can be achieved. This cell plant characteristic is of great importance in adapting to the ever-changing demand of the bio-energy market, minimizing the cost of product production and switching, and at the same time constructing a carbon-based “single carbon photomultiple†under harsh environmental extremes (such as Mars et al.). "Production mode" has a special strategic value for the flexible and controllable synthesis of energy, materials and foods necessary for human survival.
Previously, a single cell center found that up to 11 type II diacylglycerol acyltransferase-encoding genes (DGAT2) are encoded in the marine Nannochloropsis genome, which catalyzes the final and critical step in triglyceride synthesis. Only 1-2 DGAT2 are often found in animals and higher plants. Why does the marine Nannochloropsis have more DGAT2 family members than all known species? In order to solve the above problems, the researchers found that DGAT2A, DGAT2A, was identified through in-depth expression of expression and function analysis in yeast, in vitro enzyme activity identification, and further overexpression and gene knockdown in Nannochloropsis. DGAT2D and DGAT2C have TAG synthase activity, and the three DGAT2 family members prefer saturated, monounsaturated and polyunsaturated fatty acyl CoA substrates, respectively. Based on this, the researchers proposed a deeper step than the previous work (Li, et al, Plant Cell, 2014) of the oil synthesis mechanism model, which is believed to have come from three different ancestors DGAT2A, DGAT2D and DGAT2C, in the long-term In the process of co-evolution, we formed different but complementary substrate preferences, and we carried out exquisite functional division and time-space collaboration in the TAG synthesis pipeline.
Surprisingly, the relative abundances of DGAT2A, DGAT2D, and DGAT2C transcripts are positively correlated with the proportions of SFA, MUFA, and PUFA on TAG, heralding an exquisite but simple control mechanism for algal oil saturation. Using this, the researchers went a step further by artificially controlling the relative abundance of transcripts between DGAT2A, DGAT2D, and DGAT2C to achieve a rational design of the proportion of SFA, MUFA, and PUFA in algae oil, resulting in a saturation "customization." "Algae oil." In the TAG products of nearly 20 strains of Nannochloropsis, the changes in specific gravity of SFA, MUFA and PUFA reached 1.3 times, 3.7 times and 11.2 times respectively, indicating that algae oil was used as a fuel on a single industrial microalgae chassis. Or the use and value of nutritional products have good controllability and plasticity.
This work was done by the cooperation of the labs of Qingdao Institute of Energy Xu Jian, University of Maryland Li Yantao and Peking University Liu Jin, and was supported by the research institutes of Hushui Hu and Hu Xiaohua. The paper's joint work is Xin Yi and Lu Yanyi of the Single Cell Center of Qingdao Energy Institute and Yi-Ying Lee of the University of Maryland. This thesis and its predecessor work have been supported by the National Outstanding Youth Fund, the 863 Synthetic Biology Special Project of the Ministry of Science and Technology, the Carbon Gas Bio-Manufacturing Project of the Chinese Academy of Sciences, the Natural Science Youth Fund of Shandong Province, and the National Natural Science Foundation of the United States.
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