news

한어Русский языкEnglishFrançaisIndonesianSanskrit日本語DeutschPortuguêsΕλληνικάespañolItalianoSuomalainenLatina

Our reporter Gong Xiangjuan

Artificially synthesized starch samples. Photo by Cui Xinyao (People's Vision)

Core Reading

The world today faces challenges such as climate change, food security, and energy resource shortages. How can we convert carbon dioxide into substances that are meaningful and valuable to humans? The artificial starch synthesis project is one of the attempts. The Tianjin Institute of Industrial Biotechnology of the Chinese Academy of Sciences achieved a breakthrough in the project in 2018, and has been continuously upgrading its technology since then. Today, the synthesis rate of artificial starch is 8.5 times that of corn starch, and the directional and controllable synthesis of different types of starch can be achieved as needed.

The blue that I've been dreaming about appears!

In Tianjin Airport Economic Zone, at the Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences (hereinafter referred to as "TIBI"), Qiao Jing, a researcher, is repeating the daily experimental process. When drops of iodine solution were added to the test tube, Qiao Jing could not help but be stunned: the reagent turned into the long-awaited color, "Although the blue is very light, it means that starch has appeared!" Recalling the scene in 2018, Qiao Jing is still excited.

Cai Tao, the project manager of artificial starch synthesis at Tianjin Institute of Industrial Biology, was also excited. He was unsure at first and ran all the way back to the laboratory from the conference room to design a repeat experiment. The next day, "starch blue" appeared as expected. "Great!" Cai Tao was relieved and smiled. His colleagues behind him applauded and cheered.

In 2021, the artificial starch synthesis team published a paper in the international journal Science magazine that combined artificial photosynthesis and enzyme catalysis to build a new system for synthesizing starch from water and carbon dioxide. "This is a milestone breakthrough that will have a transformative impact on the next generation of biomanufacturing and agricultural production," commented the reviewer.

The origin of the artificial starch synthesis project originated from a thought on the high-speed train. "The world today faces challenges such as climate change, food security, and energy resource shortages. How can we convert carbon dioxide into substances that are meaningful and valuable to humans?" This idea suddenly occurred to Ma Yanhe, then director of the Tianjin Institute of Industrial Biology, on the high-speed train on his way back to Tianjin on a business trip. After careful research and judgment by the institute, the artificial starch synthesis project was officially proposed in 2015.

When Cai Tao received the invitation to tackle the problem, he was both excited and worried. Artificial synthesis of starch is theoretically possible, but there have been no successful cases before. "We want to challenge something that others have not done."

In nature, crops such as corn, wheat, and potatoes convert sunlight, carbon dioxide, and water into starch through photosynthesis. However, this natural process requires a lot of land and fresh water resources and is greatly affected by the weather.

Is it possible to simulate the synthesis process of starch in nature and achieve artificial synthesis of starch through technical means?

"Our initial idea was to use renewable energy to decompose water to produce electrons or hydrogen, and then use the electrons or hydrogen to reduce carbon dioxide into simple compounds such as formic acid and methanol, and further use enzymes to catalyze the polymerization of simple compounds to produce starch." Cai Tao said that the artificial synthesis of starch is an experiment to find a "shortcut."

In crops, the synthesis of starch requires about 60 metabolic reactions. If industrial production is to be carried out, the steps must be simplified. Cai Tao and his team worked with a team in the institute that specializes in biological design to systematically explore and screen 6,568 biochemical reactions, starting from formic acid or methanol, and designed the shortest artificial starch synthesis path. Theoretically, carbon dioxide can synthesize starch through only 9 main reactions. "The fewer steps, the fewer problems," said Cai Tao.

The experiment lasted for three years, and the experimental records alone piled up half a person's height. The moods of the team members also fluctuated with the progress of the experiment.

What went wrong? "Just like when a river is cut off, we need to find out whether it is blocked upstream or the river is bifurcated. Only by figuring out the root cause can we solve the problem." Cai Tao said that the most prominent problem in the experiment is "enzyme". Most reactions in the starch synthesis process require enzymes. The reaction pathways in nature have evolved through long-term natural selection, and each enzyme can adapt and cooperate, but the artificially designed reaction pathways are different.

"The same enzyme can often catalyze multiple reactions, which may cause side effects; sometimes multiple enzymes will compete for one substrate, and some enzymes will produce multiple products." In order to reconcile the "contradictions" between enzymes, Cai Tao found a team in the institute that specializes in enzyme research, and together they carried out targeted modification of enzymes or artificially designed new enzymes to meet the enzyme needs of the artificial pathway for starch synthesis.

Discussion, experiment, overturn, discussion again, experiment again... The team tried to use the energy generated by the "hydrogen combustion" in methanol to drive the reaction of producing formaldehyde, solving the problem of mismatch between thermodynamics and kinetics in the reaction. The 9 main reactions were also expanded to 11 accordingly.

Scientific accumulation is a long process, but breakthroughs are sometimes just a moment. On the morning of July 24, 2018, Cai Tao received a picture from a team member. After opening it, Cai Tao saw the long-awaited "blue".

"Looking at it now, that was just version 1.0 of artificial starch synthesis." Cai Tao said that in recent years, the team has completed the iterative upgrade of artificial starch synthesis technology, continuously improving the starch synthesis output, and increasing the starch production intensity by 136 times compared to version 1.0. The artificial starch synthesis rate is 8.5 times that of corn starch, and the directional and controllable synthesis of different types of starch can be achieved as needed.

In Cai Tao's view, the greatest success of scientific research is to be able to put it into practical application and help improve social welfare. "Next, we will accelerate the pace of scientific research results from laboratories to industrial applications, and let technological creations paint a new picture of science and technology benefiting the people," said Cai Tao.

This issue's coordinator: Chen Shihan

Layout design: Cai Huawei

People's Daily (Page 04, August 6, 2024)