Cell-Free Chemoenzymatic Starch Synthesis From Carbon Dioxide

Updated: Feb 24

The scientists of the Chinese Academy of Sciences (CAS) made a breakthrough regarding the synthesis of artificial starch. Ma Yanhe, the director of the Tianjin Institute of Industrial Biology (TIB) and the author of the paper “Cell-free chemoenzymatic starch synthesis from carbon dioxide”, explained that their research team discovered an unprecedented bioconversion method of artificial carbon dioxide fixation and starch synthesis.

The converting process happens through an artificial starch anabolic pathway (ASAP), with 11 core reactions. Carbon dioxide is initially reduced to methanol by using inorganic catalysts such as ZnO-ZrO­­2. The resulting methanol is transformed into carbon sugar molecules with the help of engineered enzymes, including formolase. Then, the sugar units are finally processed to produce starch.

Current experimental data demonstrate that synthetic starch produced through the process they developed is structurally identical to natural starch, but with an 8.5-fold higher production rate. Starch synthesis through natural photosynthesis involves more than 60 biochemical reactions with 2 per cent energy efficiency. The newly presented approach can save more than 90 per cent of land and freshwater resources if the overall production cost can be reduced to a more economically feasible level. With sufficient energy supply and contemporary technology, the predicted starch production of 1cubic metre is equivalent to the annual production of starch of 5 mu (0.33 hectare) of corn.

“The design of artificial biological system to synthesize starch independent of plant photosynthesis is a major disruptive technology that will have a great impact on the world,” the expert with CAS told Global Times.

The research team believes that this new technology has the potential to replace conventional cultivation with industrial-scale manufacturing and open a new direction for future technology. Also, it is expected to present high potentials to support food security while preventing the usage and the negative consequences of pesticides and chemical fertilizers.

However, there are also negative opinions about this approach. Harvey Millar, the director of the Australian Research Council Centre of Excellence in Plant Energy Biology at the University of Western Australia, commented that switching from today’s agricultural practice to a new method will encounter many technological barriers and require a long time to prepare and implement. “It’s interesting for sure, but won’t be stopping people growing plants in agriculture for starch any time soon,” he said. He pointed out that the new method requires constant replacement of the synthetic enzymes as they lack high stability, which is an unnecessary step with plants.

The team also acknowledges that more study is needed before the carbon dioxide bioconversion method can be industrialized for large-scale production. Ma explained that their next challenge is to focus on improving the activity and stability of synthetic enzymes to decrease the cost for artificial starch synthesis.

Climate change and food shortage, in addition to soil and water contamination, are some of the many challenges humanity faces. Although further advancement in technology and extensive research on this new biotechnology is required, this breakthrough presents the potential of promoting carbon neutrality and the possibility of a new agricultural paradigm.

Edited by: Park, Jihye and Park, Changmo

References Cai, T., Ma, Y., Qiao, J., Sun, H., & Zhu, L. (2021, September 24). Cell-free chemoenzymatic starch synthesis from carbon dioxide. Science. Retrieved September 29, 2021, from https://www.science.org/doi/10.1126/science.abh4049 Qi, W. (2021, September 24). Chinese scientists complete starch synthesis from CO2, revolutionary for agricultural production and promoting carbon neutrality. Global Times. Retrieved September 29, 2021, from https://www.globaltimes.cn/page/202109/1235013.shtml

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