How to Make Carbon-Negative Chemicals

Bacteria engineered to turn carbon dioxide into compounds used in paint remover and hand sanitiser could offer a carbon-negative way of manufacturing industrial chemicals.

Michael Köpke at LanzaTech in Illinois and his colleagues searched through strains of an ethanol-producing bacterium, Clostridium autoethanogenum, to identify enzymes that would allow the microbes to instead create acetone, which is used to make paint and nail polish remover. Then they combined the genes for these enzymes into one organism. They repeated the process for isopropanol, which is used as a disinfectant.

The engineered bacteria ferment carbon dioxide from the air to produce the chemicals. “You can imagine the process similar to brewing beer,” says Köpke. “But instead of using a yeast strain that eats sugar to make alcohol, we have a microbe that can eat carbon dioxide.” After scaling up the initial experiments by a factor of 60, the team found that the process locks in roughly 1.78 kilograms of carbon per kilogram of acetone produced, and 1.17 kg per kg of isopropanol. These chemicals are normally made using fossil fuels, emitting 2.55 kg and 1.85 kg of carbon dioxide per kg of acetone and isopropanol respectively.

This equates to up to a 160 per cent decrease in greenhouse gas emissions, if this method were to be broadly adopted, say the researchers. The technique could also be made more sustainable by using waste gas from other industrial processes, such as steel manufacturing.

Excerpt from Chen Ly, Engineered bacteria produce chemicals with negative carbon emissions, New Scientist, Feb. 21, 2022

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