Bacteria that absorbs CO2 and turns it into useful chemicals

You don’t hear it every day, but it’s (relatively) easy to make energy without oil. But there are a number of substances we rely on with production methods that are harder to decarbonise.

Among these are industrial chemicals such as acetone and isopropanol, which have a combined global market of $10 billion (US – around $14 billion AU). Acetone is used as a solvent for making plastics and in cleaning agents, while isopropanol is an ingredient in hand sanitisers (among other applications).

Now a group of US researchers have figured out a fossil-free way to make these chemicals. Their method – which relies on specially engineered bacteria – is actually carbon-fixing.

It revolves around the bacterial strain Clostridium autoethanogenum, which US company LanzaTech has engineered to convert carbon monoxide into ethanol.

With some genetic modifications, the researchers (who are based at LanzaTech and Northwestern University, US) found that C. autoethanogenum could absorb carbon dioxide and convert it into both acetone and isopropanol.

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According to the paper, every commercial kilogram of acetone produced releases an average 2.55 kilograms of carbon dioxide into the atmosphere, while a kilogram of isopropanol is responsible for 1.85 kg CO₂.

While the C. autoethanogenum doesn’t completely remove all the CO₂ it’s fermented with, it’s still a carbon negative process.

The researchers were able to demonstrate that they could make the process work in a 120-litre reactor, with carbon dioxide and monoxide gas being pumped through the bacteria. This means it could operate at an industrial scale, potentially collecting carbon emissions from agricultural or industrial waste.

They have described their discovery in a paper published in Nature Biotechnology.

“By harnessing our capacity to partner with biology to make what is needed, where and when it is needed, on a sustainable and renewable basis, we can begin to take advantage of the available CO₂ to transform the bioeconomy,” says co-author Michael Jewett, a researcher at Northwestern University.

“Today, most of our commodity chemicals are derived exclusively from new fossil resources such as oil, natural gas or coal,” says Jennifer Holmgren, CEO of LanzaTech.

“The acetone and IPA pathways developed will accelerate the development of other new products by closing the carbon cycle for their use in multiple industries.”