Keeping the world fed is not an easy task; in fact, it causes immense environmental damage due to the massive use of land, water, fertilizer, pesticides, and fuel. From being used in everything from bread to paper, starch has a secured place in this list, yet we rely on plants to manufacture it, which is rather inefficient. For a more sustainable approach, a team at the Chinese Academy of Sciences has designed what they say is the first method to turn CO2 into starch more efficiently than plants do, according to a press release.
This is a significant breakthrough since it has been difficult to accelerate photosynthesis in plants or create starch artificially in the past. While scientists were successful at making starch from plant-derived cellulose or from sucrose by using enzymes, using CO2 hadn't been possible until now. The novel technique reported in the study published in Science uses chemical catalysts and a carefully selected combination of natural and engineered enzymes to convert CO2 to starch 8.5 times more efficiently than corn plants.
This hybrid solution involves the CO2 first being reduced to methanol with the help of an organic catalyst. The methanol is then treated with engineered enzymes, which convert it to sugar units, which are then converted into polymeric starch. The complete process consists of only 11 core reactions and has greater efficiency than corn. The resulting synthetic starch, according to the researchers behind it, has the same structure as real starch and could be made in significantly less space.
"If the overall cost of the process can be reduced to a level economically comparable with agricultural planting in the future, it is expected to save more than 90 percent of cultivated land and freshwater resources," explains Yanhe Ma, a microbiologist at the Tianjin Institute of Industrial Biotechnology and corresponding author of the study.
While the method is a long way from being scaled up due to problems such as manufacturing the right reactor, the researchers believe the breakthrough offers a new scientific foundation for future technologies that produce industrial quantities of starch from CO2, potentially opening up a new route for synthesizing other complex molecules from the gas. This could help to improve food security while reducing the usage of environmentally harmful pesticides and fertilizers. The researchers want to focus on increasing the efficiency of the technique in the future by working on improvements.
"Next, we will focus on increasing the activity and stability of the enzymes we used to significantly decrease the cost for artificial starch synthesis," Ma says.