Science and Technology News
Chinese scientists have once again turned carbon dioxide into waste: reducing it to produce glucose and oil
Schematic diagram of high energy long chain food molecules synthesized by carbon dioxide in vitro. Research team provided the picture
Beijing, April 28 (Reporter Sun Zifa) Can carbon dioxide "change" anything other than starch? The latest answer given by Chinese scientists is "yes" - can be reduced to synthesize glucose and oil.
After the first de nio synthesis of carbon dioxide to starch in the world, the team of Chinese scientists once again realized the "waste into treasure" of carbon dioxide, they successfully reduced the efficiency of carbon dioxide to synthesize high concentration acetic acid through electrocatalysis combined with biosynthesis, and further used microorganisms to synthesize glucose and oil.
Synthesis of acetic acid by CO reduction catalyzed by grain boundary copper. Research team provided the picture
Schematic illustration of the conversion of carbon dioxide and water into long-chain products through electrochemical coupled biological fermentation. Research team provided the picture
Industrial waste gas becomes "vinegar" under mild conditions
In this case, how exactly does carbon dioxide turn into glucose and oil?
Zeng Jiekop said that, first of all, it is necessary to convert carbon dioxide into raw materials that can be used by microorganisms to facilitate microbial fermentation. The clean, efficient electrocatalytic technology, which can work at normal temperature and pressure, is ideal for this process, and the team has developed a number of mature electrocatalyst systems.
As for what kind of "raw material" to turn into, the researchers set their sights on acetic acid. Because it is not only the main component of vinegar, but also an excellent source of biosynthetic carbon that can be converted into other biological substances such as glucose.
"Acetic acid can be obtained by direct electrolysis of carbon dioxide, but the efficiency is not high, so we adopt a 'two-step' strategy - first efficient to obtain carbon monoxide, and then from carbon monoxide to acetic acid." Zeng Jie said.
Natsuchuan pointed out that the acetic acid produced by conventional electrocatalytic devices is mixed with many electrolyte salts and cannot be directly used for biological fermentation. Therefore, in order to "feed" microorganisms, it is not only necessary to improve the conversion efficiency and ensure the quantity of "food", but also to obtain pure acetic acid without electrolyte salts to ensure the quality of "food".
The research team used a new solid electrolyte reaction device to replace the original electrolyte salt solution with a solid electrolyte, and directly obtained a pure acetic acid aqueous solution without further separation. With this device, acetic acid aqueous solution with purity up to 97% can be prepared continuously for more than 140 hours in a stable current density.
Glucose and fatty acids were synthesized from acetate and acetic acid as carbon sources. Research team provided the picture
Engineering transformation of Saccharomyces cerevisiae strains. Research team provided the picture
Microbes get jealous and produce glucose
Yu said that after obtaining the acetic acid, the research team tried to use saccharomyces cerevisiae, a microbe, to synthesize glucose. This process is like microbes in "vinegar", saccharomyces cerevisiae through continuous "vinegar" to synthesize glucose, but in this process, saccharomyces cerevisiae itself will metabolize part of the glucose, so the output is not high.
In this regard, the research team abolished the ability of saccharomyces cerevisiae to metabolize glucose by knocking out three key enzyme elements in saccharomyces cerevisiae. After the knockout, the engineered yeast strains in the experiment produced a glucose yield of 1.7 grams per liter under shake-flask fermentation conditions.
In order to further increase the production of synthetic glucose, it is necessary not only to abolish the capacity of saccharomyces cerevisiae, but also to strengthen its own ability to accumulate glucose. The researchers then knocked out two suspected glucose metabolizing enzyme elements and inserted glucose phosphatase elements from Pantothenia and E. coli.
Yu said the two enzymes can "find a new way" to convert phosphoric acid molecules from other pathways in the yeast body to glucose, increasing the yeast's ability to accumulate glucose. After the modification, the glucose yield of the engineered yeast strain reached 2.2 grams per liter, which increased the yield by 30%.
The yeast strain fermentation liquid (brown solution) for preparing glucose after modification, and the prepared glucose (white solution). Research team provided the picture
Solid electrolyte reactor. Research team provided the picture
New catalytic methods facilitate the production of high value-added compounds
In recent years, with the rapid rise of new energy power generation and the decrease of electricity costs, carbon dioxide electric reduction technology has the potential to compete with traditional chemical processes that rely on fossil energy. Therefore, the process of efficient carbon dioxide electroreduction to produce high value-added chemicals and fuels is considered to be one of the important research directions for the construction of future "zero carbon emission" substance conversion.
Xia Chuan said that in order to avoid the product limitations of carbon dioxide electroreduction, it can be considered to couple the carbon dioxide electroreduction process with the biological process, and use the electrocatalytic product as an electronic carrier for the subsequent fermentation of microorganisms to grow carbon chain chemical products for production and life.
As a living cell factory, microorganisms have the advantage of high product diversity and can synthesize many compounds that cannot be produced artificially or with low artificial production efficiency, which is a very rich "material synthesis toolbox".
Zeng Jie believes that through the new catalytic method of electrocatalysis combined with biosynthesis, the added value of carbon can be effectively increased. The research team will further study the compatibility and compatibility of the two platforms of electrocatalysis and biological fermentation. In the future, if you want to synthesize starch, make pigments, and produce drugs, you only need to keep the electric catalytic facilities unchanged and change the microorganisms used in fermentation.
The research team prepared sodium acetate powder through a solid electrolyte reactor. Research team provided the picture
Provide new technology for artificial semi-artificial synthesis of "food"
Li Can, academician of the Chinese Academy of Sciences and director of the Chinese Catalysis Committee, commented that the latest research work coupled the artificial electrocatalysis and biological enzyme catalysis process, developing a new way from water and carbon dioxide to small chemical molecules containing energy acetic acid, and then engineered yeast microorganisms catalyzed the synthesis of high value-added products such as glucose and free fatty acids. New technologies are provided for artificial and semi-artificial synthesis of "food".
Deng Zixin, academician of the Chinese Academy of Sciences and director of the State Key Laboratory of Microbial Metabolism of Shanghai Jiao Tong University, believes that the research work opens up a new strategy of electrochemical synthesis of food products such as glucose and living cell catalysis, provides a new paradigm for the further development of new agricultural and biological manufacturing based on electric drive, and is an important development direction in the utilization of carbon dioxide. (over)
Source: Chinanews.com
