A breakthrough from 0 to 1!

——The significance and prospect of synthetic starch

  Our reporter Shen Hui

  Imagine that there is no need to cultivate land or green plants. Using sunlight, water and carbon dioxide as raw materials, starch can be produced continuously in the factory like plants.

Isn’t it amazing?

Today, this seemingly unattainable scene is expected to be realized in the near future.

  Recently, good news came from the Tianjin Institute of Industrial Biotechnology of the Chinese Academy of Sciences: After 6 years of technical research, the scientific research team has made major breakthroughs in the artificial synthesis of starch, and achieved the de novo synthesis of carbon dioxide into starch for the first time in the world.

  Do not rely on plant photosynthesis, design an artificial biological system to fix carbon dioxide and synthesize starch, which is considered by the international academia to be a major disruptive technology that will affect the world. What is so powerful?

What is the scientific and practical significance of the breakthrough?

The reporter interviewed the author of the paper and related experts.

Break through the bottleneck

  The Chinese prefer to eat carbon water. The Qing Dynasty gourmet Yuan Mei once wrote in "Suiyuan Food List", "The congee and rice are also served, and the rest of the vegetables are also at the end", which shows that Chinese people's love for carbon water.

The carbohydrates mentioned here are carbohydrates, which are composed of carbon, hydrogen, and oxygen, and are essential elements for human survival.

Starch is the most important carbohydrate in "porridge and rice". It is the main ingredient of flour, rice, corn and other grains. It is the most important food material to feed the global population, and it is also an important industrial material.

  For many years, crops have used photosynthesis to synthesize water, carbon dioxide and other inorganic compounds into carbohydrates such as sugars and starches that can be used as animal feed and human food. This is the most important biochemical reaction process on the earth.

But is this the most efficient way to produce starch?

the answer is negative.

  According to data provided by Ma Yanhe, the corresponding author of the paper and director of the Tianjin Institute of Industrial Biology, in corn and other crops, the conversion of carbon dioxide into starch involves about 60 metabolic reactions and complex physiological regulation, and the utilization efficiency of solar energy is less than 2%.

"Plants have evolved over hundreds of millions of years to adapt to the natural environment, and their inherent properties restrict the efficient synthesis of starch." Ma Yanhe said.

  Is there a way to get rid of plants to synthesize starch?

Since the birth of synthetic biology, people have tried to artificially construct unnatural pathways to realize the conversion of carbon dioxide into starch, in order to break through the bottleneck of plant-mediated photosynthesis.

However, due to unclear technical routes and unpredictable bottlenecks, there are many uncertainties in this scientific research road.

  Ma Yanhe and others decided to bravely enter the "no man's land."

Since 2015, with the support of the key deployment project of the Chinese Academy of Sciences and the special financial project of Tianjin, the Tianjin Institute of Industrial Biology has established a project to carry out research on carbon dioxide synthesis starch.

  After 6 years of fierce battle, the research team finally got its wish.

Cai Tao, the first author of the paper and an associate researcher at the Tianjin Institute of Industrial Biology, said excitedly: "We compare synthetic starch with natural starch, and the NMR results are exactly the same. It can be said that synthetic starch is actually indistinguishable from natural starch. of."

  what does this mean?

Statistics show that in 2019, nearly 750 million people in the world are facing severe food insecurity, accounting for nearly one-tenth of the world's total population.

"Even if it replaces a part of grain starch as industrial raw material or even feed, it is also a great contribution to alleviating agricultural pressure." Ma Yanhe said.

Technology path

  Using carbon dioxide to synthesize starch artificially, how is this disruptive technology made?

Ma Yanhe told reporters that from an energy perspective, the essence of photosynthesis is to convert sunlight energy into chemical energy stored in starch.

  How can light energy be converted into chemical energy more efficiently?

To simulate and learn from natural processes to construct new artificial photosynthetic pathways, researchers thought of the energy conversion method of light energy-electricity-chemical energy. First, photovoltaic power was used to convert light energy into electrical energy, and hydrogen gas was generated through photovoltaic hydrolysis, and then through catalysis. The use of hydrogen to reduce carbon dioxide to methanol and convert electrical energy into chemical energy stored in methanol. The energy conversion efficiency of this process exceeds 10%, far exceeding the energy utilization efficiency of photosynthesis.

  Methanol stores energy from solar energy, but the life process of methanol synthesis of starch does not exist in nature.

As a result, researchers used the idea of ​​synthetic biology to design an artificial route ASAP from methanol to starch with a large amount of biochemical reaction data containing only 10 steps of the main reaction.

  In order to turn the blueprint into reality, the researchers also excavated and modified 62 bio-enzyme catalysts from 31 different species, including animals, plants, and microorganisms. In the end, the best was selected, and 10 enzymes were used to gradually convert one-carbon methanol into The three-carbon dihydroxyacetone is further converted into six-carbon glucose phosphate, and finally linear and amylopectin are synthesized.

  "This is a process of realizing artificial photosynthesis to synthesize starch." Ma Yanhe said, from the perspective of scientific breakthroughs, this artificial way of starch synthesis has taken a big step toward the realization of natural design and surpassing natural goals. The creation of new functional biological systems provides a new scientific basis.

  From the perspective of technological innovation, through the development of efficient artificial catalysts and biological enzymes, the research team designed a new way to fix carbon and artificially synthesize starch from 6,568 biochemical reactions.

According to the calculation of the photoelectric conversion efficiency of 20%, this new chemical and biological hybrid synthetic starch system has a theoretical energy conversion efficiency of 7%, and its starch synthesis rate is 3.5 times higher than that of natural photosynthesis.

  what does this mean?

Cai Tao explained that according to current technical parameters, under the condition of sufficient energy supply, the theoretical annual starch output of a 1 cubic meter bioreactor is equivalent to the starch output of 5 acres of corn planting (according to the average output of corn starch in my country) Calculation), "This achievement opens a window for industrial workshop manufacturing from carbon dioxide to starch production."

Application prospects

  According to Chen Jian, former president of Jiangnan University and academician of the Chinese Academy of Engineering, food production occupies about 40% of the world’s arable land and generates 25% of greenhouse gases. As one of the most important food ingredients, the sustainable supply of starch is the future of mankind. Important challenge.

This research result combines chemical and biological methods and uses a series of new technologies such as protein engineering and synthetic biology to directly synthesize starch from carbon dioxide, completely subverting the traditional starch production method.

This research work is a typical "0 to 1" original result, which not only has a revolutionary impact on future agricultural production, especially food production, but also has a milestone significance for the development of the global biomanufacturing industry.

  Ma Yanhe said that if the cost of the system is economically feasible compared with agricultural planting in the future, and it is practically applied, it will be possible to save more than 90% of arable land and fresh water resources, avoid the negative impact of pesticides and fertilizers on the environment, and increase Human food security level.

  However, he also emphasized that the results are still in the laboratory stage, and there is still a long way to go before practical applications, and they face many challenges.

  "Following up, the research team also needs to realize the conceptual breakthrough from '0 to 1'to the conversion from '1 to 10' and '10 to 100' as soon as possible, so that this technology will eventually become an effective means and tool for solving human development problems." Zhou Qi, vice president of the Chinese Academy of Sciences, said that the Chinese Academy of Sciences will integrate relevant scientific and technological forces and continue to support the in-depth advancement of this research.

  "The world today is facing a series of major challenges such as global climate change, food security, shortage of energy resources, and environmental pollution. Scientific and technological innovation has become a key factor in reshaping the global pattern and creating a better future for mankind. The conversion and utilization of carbon dioxide and artificially synthesized starch, It is one of the major scientific and technological issues to deal with the challenge." Zhou Qi said.

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