▲ Scientific research team of synthetic starch.
▲ Cai Tao (left) discusses with technicians. Engineering model of synthetic starch.
Synthetic starch samples.
The synthetic starch turns blue with iodine.
Engineering test platform for synthetic starch.
The pictures in this version are all provided by Tianjin Institute of Engineering and Students except for the notes
■ Our reporter Liu Runan
Starting from Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences (hereinafter referred to as Tianjin Institute of Industrial Biotechnology), you will come to a place full of "magic" by walking 4000 meters southeast.
This is an engineering test platform, where various instruments are placed compactly and the test equipment is booming. Soon, methanol synthesized from carbon dioxide in the fermentation tank will react with specific biocatalyst enzyme one by one, and finally turn into tubes of white starch.
On September 24, 2021, Tianjin Institute of Engineering and Students achieved a major breakthrough in de novo synthesis of carbon dioxide to starch for the first time in the world, and related achievements were published online in Science. At the end of 2022, it will take another critical step from the laboratory to the production line, and build a tonnage pilot plant, which is currently undergoing testing.
First "from 0 to 1", and then "from 1 to 10", Tianjin Institute of Industrial and Health Sciences is committed to solving the food problem facing human development.
Is it possible to make starch by "emptiness"
As an important kind of high molecular carbohydrate, starch is the core product of agricultural civilization, providing the heat needed for human survival. For more than 10000 years, agricultural planting has been the only way to produce starch.
However, low energy efficiency of plant photosynthesis and long growth cycle may cause food security problems. For this reason, scientists have explored the methods of hybrid breeding, module breeding, molecular breeding, etc., and also established an artificial photosynthetic system.
"These are not separated from the carbon fixation mode of plants themselves. It is like running fast, but essentially relying on both feet. Can you jump out of this mode and directly build a 'car' to put food production on the fast track?" One day in 2014, on the high-speed railway from Beijing to Tianjin, Tianjin Institute of Engineering and Students, the founding director Ma Yanhe, the chief scientist of the carbon dioxide synthesis starch project, thinks like this.
As a scientific research institution dedicated to the development of industrial biology, Tianjin Institute of Industry and Students has always pursued an important goal - to cultivate organisms in industrial workshops and use them to produce agricultural materials, that is, to achieve "agricultural industrialization".
At a seminar held by Tianjin Institute of Engineering and Students, Ma Yanhe continued to open his mind: "We simply imitate a plant, synthesize a cell, and let it use the carbon dioxide in the air to synthesize the necessary substances. That is the real 'make things out of nothing, do what you want'!"
After careful demonstration, everyone agreed that it was too difficult to synthesize cells, but it might be possible to try to synthesize starch using carbon dioxide outside the cell.
Ma Yanhe said that today's world is facing a series of major challenges such as climate change, food security, shortage of energy resources, ecological environment pollution, and scientific and technological workers shoulder a heavy responsibility. The conversion and utilization of carbon dioxide and the industrial synthesis of grain starch are just one of the major scientific and technological issues to meet the challenges.
In January 2015, Cai Tao, an associate researcher of Tianjin Institute of Engineering and Students who was also visiting the University of Minnesota in the United States, received a phone call from Ma Yanhe: "The Institute is planning to do a project of making starch out of thin air."
"Made out of thin air? Is it possible?" Cai Tao was surprised and excited. At that time, he had joined Tianjin Institute of Engineering and Students for more than two years. With the idea of "doing application-oriented basic research", he turned from traditional biology to synthetic biology research, and went abroad to study in May 2014.
Cai Tao felt that this project was of great significance, but he was always in a state of mind about how to do it and whether it could be done.
The preliminary survey results are not optimistic. On hearing of this idea, even well-known experts in the field shook their heads. "Plant photosynthesis has existed for more than one billion years, and the system mechanism has not been fully understood yet. Can you synthesize from scratch?"
Everyone's doubts are not unreasonable. This is something that no one has ever done. We can't find any clues about the synthesis path and research methods through all the literature at home and abroad.
"Can you turn your head and think about what plants can do? How can we not do it?" Ma Yanhe said that at that time, Tianjin Institute of Engineering and Students had realized the heterologous cell synthesis of a number of effective components of medicinal and economic plants, such as ginseng, gastrodia elata, rhodiola, etc., designed a new route of biosynthesis for sugar, meat, oil, protein, etc., and had accumulated a lot in changing the traditional farming model.
2. Innovate the organizational model and institutionalize scientific research
On January 1, 2016, the key deployment project of the Chinese Academy of Sciences, "Artificial Biotransformation of Carbon Dioxide", was officially approved. This project is in the charge of Tianjin Institute of Engineering and Students. It aims to transform carbon dioxide into complex organic matter through efficient use of chemical energy, light energy, electric energy and other forms of energy, and allocate some funds from it for the early exploration of "carbon dioxide synthesis of starch".
Different from many scientific research organization models that rely on the leader responsibility system, the carbon dioxide synthesis starch project was carried out organically at the beginning, adopting the three-dimensional scientific research organization model of "overall research department - characteristic research group - platform laboratory".
The General Research Department is responsible for refining major scientific and technological tasks and determining key research goals around major scientific issues of engineering biology and key core technologies of the biological industry. Once the project is approved, a senior researcher will serve as the chief scientist and appoint a "project manager" in the whole institute and even the whole society.
Then, under the guidance and help of Ma Yanhe and Wang Qinhong, the assistant director of Tianjin Institute of Engineering and Students, the carbon dioxide synthesis starch project team condensed problems and divided tasks according to the project objectives, and recruited and organized elite teams for the Institute to carry out collaborative research.
At the beginning of the project, except Ma Yanhe, Wang Qinhong and Cai Tao, the project team only had four main technicians to undertake the experimental technical work. During the three-year cycle, they only do this project. If necessary, they will contact the internal and external scientific research teams to cooperate.
When the project was officially launched, all team members felt great pressure. In the natural reaction of plants, starch synthesis and accumulation involve about 60 steps of metabolic reaction and transportation between organelles. To carry out industrial production, it must be simplified, while ensuring that the reaction is sufficient and accurate.
To this end, the team cooperated with Ma Hongwu, a researcher of Tianjin Institute of Engineering and Health, to develop a new algorithm, and systematically mined and screened the synthesis path among 6568 biochemical reactions, and calculated the shortest synthesis path.
There are nine main reactions in this way, roughly chemical reaction is carried out first, carbon dioxide is reduced to carbon one compound by using high density electric/hydrogen energy, and then biological reaction is carried out to polymerize carbon one compound into carbon three compound, carbon six compound (i.e. glucose) and long chain starch molecule.
But this is just a virtual way of theory, and then it must be turned into reality.
3. Three years of research and development, "starch blue"
Although the difficulty of the project has been estimated, after the experiment started, the difficulty still exceeded everyone's imagination.
The most prominent one is the problem of enzymes. Each step of the reaction requires the participation of enzymes. According to the calculated path, many enzyme combinations have never appeared in reality.
Unlike "one key opens one lock", the same enzyme can often catalyze multiple reactions, which will bring "side effects". Sometimes, one substrate is competed by multiple enzymes, resulting in no substrate available for subsequent enzymes; Sometimes, it "hits the spot" with the substrate that does not need to be combined, but "has little interest" in the substrate that needs to be combined.
For a long time, team members were fighting with these enzymes. They cooperated with the team of Jiang Huifeng, a researcher who is best at new enzyme design in Tianjin Institute of Engineering and Students, and the team of Zhu Leilei, a researcher who is best at enzyme evolution and transformation, to carry out directional transformation of existing enzymes, or design new enzymes from scratch, create unnatural artificial enzymes, to solve the problem of enzyme combination optimization.
In 2018, the 3-year project is about to be completed. The team has achieved the synthesis of carbon compounds to starch, but is stuck in the previous step - from carbon dioxide to carbon compounds reduction reaction.
At that time, there were two alternative routes: one was to convert carbon dioxide into formic acid, and then formic acid into formaldehyde; The second is to convert carbon dioxide into methanol, and then convert methanol into formaldehyde. Either way, the amount of formaldehyde obtained from the reaction is not enough to support the subsequent reaction.
In those days, team members became extremely sensitive, doubting every step they did, guessing whether the solution was added incorrectly, the dosage was not accurate, or they made other low-level mistakes. However, after repeated, they had to face the fact that there were no mistakes in the operation and the reaction could not be advanced.
Cai Tao can't remember how many times he discussed the formaldehyde reaction amount with Ma Yanhe and You Chun, a researcher at Tianjin Institute of Engineering and Students. He gradually found a way of thinking through continuous discussion - to use the energy generated by the "hydrogen combustion" in methanol to drive the reaction to generate formaldehyde, and solve the thermodynamic matching problem in the formaldehyde reaction.
On the afternoon of July 24, 2018, Cai Tao was in the conference room on the upstairs of the laboratory, preparing to attend the stage review meeting of key projects of the Chinese Academy of Sciences, when he suddenly received a photo from the laboratory technician. The three reagent tubes in the picture are side by side, and the iodine solution in the intermediate reagent tube added with the latest test product is light blue purple, which is obviously compared with the colorless reagent tubes on the left and right sides and dark blue reagent tubes.
Cai Tao immediately called to confirm, still worried after receiving a positive reply, and trotted back to the laboratory. Until he saw the reagent tube with his own eyes, he couldn't help shouting: "Great! The manufacturing path has finally been opened up!"
On that day, everyone's face changed from the seriousness of the past few days and was full of smiles. Cai Tao immediately reported to Ma Yanhe, "This is the most beautiful color I have ever seen.".
So far, the carbon dioxide de novo synthesis of starch has finally achieved "from 0 to 1", and the synthetic output has reached 30 mg/l.
4 institutes seek cooperation outside to welcome the highlight moment
The project team did not stop at this point, but decided to continue to carry out follow-up research and "fight" with the enzyme to improve the synthesis rate and output.
In the following months, they solved the problems of low rate limiting enzyme activity, cofactor inhibition, adenosine triphosphate (ATP) competition and so on through targeted modification of key enzymes.
At the end of 2018, the key deployment project of the Chinese Academy of Sciences, "Artificial Biotransformation of Carbon Dioxide", was concluded. The project team increased the yield of starch synthesis by 8 times to 200 to 300 mg/L, far exceeding the initial goal of the project. This means that the carbon dioxide synthetic starch project ushered in the era of 2.0.
"From the initial 'blind confidence', to being hit to the bottom by various difficulties, until the 1.0 and 2.0 versions were gradually made, everyone's confidence was gradually built up," Cai Tao said.
On June 24, 2019, under the guidance of Ma Yanhe, Cai Tao and Jiang Huifeng came to Dalian Institute of Chemical Physics, Chinese Academy of Sciences (hereinafter referred to as Dalian Institute of Chemical Physics) with the latest progress information to seek cooperation.
At that time, the Li Can team, an academician of the Chinese Academy of Sciences and a researcher of Dalian Institute of Chemical Physics, had been working hard for more than 20 years and realized the production of green hydrogen by electrolysis of water and methanol by adding green hydrogen and carbon dioxide. If this path can be coupled with the biological reaction path of carbon dioxide synthesis of starch, a new breakthrough may be achieved.
After listening to the introduction of the project team, Li Can showed great interest and the two teams hit it off.
Later, the project team took the methanol synthesized by Li Can's team back to the laboratory of Tianjin Institute of Engineering and Students for subsequent starch synthesis experiments, and found that it could be synthesized normally, and the reaction rate was the same as that of commercial methanol.
The spatiotemporal separation strategy of reaction was further adopted to solve the problem of incompatibility between chemical and biological reactions, and a biochemical cascade reaction system was established. The project team increased the yield of starch synthesis by 17 times to 1.6 g/L, realizing the controllable synthesis of different types of starch.
The 3.0 version of carbon dioxide synthesis of starch appeared, and the rate of starch synthesis in this artificial way was significantly higher than that of corn starch.
On September 24, 2021, Science magazine published this achievement online, and the team finally achieved fruitful results after six years of technical research.
After the release of the results, the academic circle and social public opinion were suddenly ignited, and "carbon dioxide synthesis of starch" quickly became a hot topic.
Experts at home and abroad have said that this achievement is a "typical original breakthrough from 0 to 1"; It is a major breakthrough in the frontier research field of expanding and improving the ability of artificial photosynthesis, and has the great significance of "standing tall and upright"; It 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 bio manufacturing industry.
5. Fully reduce costs and promote industrialization
The morning after the paper was published, the cell phones of team members kept ringing. In addition to media reports and peer congratulations, research teams, biotechnology companies and consulting companies seeking cooperation have also come in droves. There are also people's expectations and doubts about the industrialization of this achievement.
At the center of the information vortex, Cai Tao was excited, nervous and worried. "At that time, the whole person was very confused, and I didn't expect that it would cause so much attention."
How to do the follow-up scientific research? Dare to do industrialization? If the engineering test is carried out with huge investment, what if it fails? We have reached a new fork in the road and must make a choice. After careful consideration, the project team finally made up its mind to do!
"Industrialization is our initial ideal as well as our ultimate goal. How can we be reconciled when we are halfway through such a difficult climb?" Ma Yanhe said.
In August 2022, Tianjin Institute of Industry and Health established the Research Center for Synthetic Starch (hereinafter referred to as the Starch Center) to accelerate the engineering application of synthetic starch, promote the manufacturing of grain component workshops, and focus on solving the cutting-edge basic science and applied basic science problems behind the industrial application.
The starch center still adopts the three-dimensional scientific research organization mode, operates according to the overall research department mechanism, provides stable support and tolerant scientific research environment at the research institute level, and cultivates the core R&D team willing to sit on the "bench".
"Early practice has shown that the three-dimensional scientific research organization model can effectively overcome the problem of scientific research fragmentation, give play to the advantages of different disciplines, integrate the advantages of scientific research institutes and enterprises to carry out efficient collaborative research, and give full play to the advantages of systematization and institutionalization," Ma Yanhe said.
At present, the starch center has gathered about 20 elite people, and will increase to about 30 people in the future.
By the end of 2022, the engineering test platform for carbon dioxide synthetic starch will be completed, and 100 upgraded and ton scale pilot plants will be launched for testing. This means that the whole synthesis path is out of the laboratory and into the production line for the first time, and the scientific research team is officially moving towards the goal of "from 1 to 10".
The good news coming together with the completion of the test platform is that the project of "Key Technology and Application of Synthetic Starch" has received special support from the Chinese Academy of Sciences for strategic leading science and technology. Ma Yanhe said: "This makes our researchers full of confidence and confidence again."
Today, the main goal of the scientific research team is to "reduce costs", and the core problem is still enzymes. They hope to continuously improve the reaction efficiency of enzymes, so that expensive enzymes can be recycled. At the same time, efforts should be made to find and solve the problems that may occur after the reaction scale is expanded, such as blocked efficiency, blocking, mutual inhibition, etc., and constantly improve the process flow.
Mayanhe expects to reduce the cost of starch synthesis to the same level or even lower than that of agricultural planting. "That will save more than 90% of cultivated land and fresh water resources, avoid the negative impact of pesticides, fertilizers, etc. on the environment, ease agricultural pressure, and help carbon neutral bio economy development."
There is still a long way to go. Now, the research team of synthetic starch is more convinced that: although the road is far, the line will come; Difficult as it is, you will succeed.
