e coli bacteria petri dish

Scientists use E. coli to convert carbon dioxide into storable form

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A new process allows E. coli to convert carbon dioxide (CO2) into a storable form and could be used to scrub emissions from polluting industries.

Scientists at the University of Dundee have developed the process, which involves starving the bacteria of oxygen and flooding it with CO2 instead at a high atmospheric pressure.

Cutting CO2 emissions to slow down and even reverse global warming has proved to be a considerable technological challenge.

The UK government has funded carbon capture trials that take CO2 produced by power stations and store it underground. However, these efforts were ultimately deemed not successful enough to be worth continued funding. 

Professor Frank Sargent, who worked on the project, said: “Reducing carbon dioxide emissions will require a basket of different solutions, and nature offers some exciting options. Microscopic, single-celled bacteria are used to living in extreme environments and often perform chemical reactions that plants and animals cannot do.

“For example, the E. coli bacterium can grow in the complete absence of oxygen. When it does this it makes a special metal-containing enzyme, called ‘FHL’, which can interconvert gaseous carbon dioxide with liquid formic acid. This could provide an opportunity to capture carbon dioxide into a manageable product that is easily stored, controlled or even used to make other things. The trouble is, the normal conversion process is slow and sometimes unreliable.

“What we have done is develop a process that enables the E. coli bacterium to operate as a very efficient biological carbon capture device. When the bacteria containing the FHL enzyme are placed under pressurised carbon dioxide and hydrogen gas mixtures – up to 10 atmospheres of pressure – then 100 per cent conversion of the carbon dioxide to formic acid is observed. The reaction happens quickly, over a few hours, and at ambient temperatures.

“This could be an important breakthrough in biotechnology. It should be possible to optimise the system still further and finally develop a ‘microbial cell factory’ that could be used to mop up carbon dioxide from many different types of industry. Not all bacteria are bad. Some might even save the planet.”

Not only capturing carbon dioxide but storing or recycling it is a major issue. There are millions of tonnes of CO2 being pumped into the atmosphere every year.

For the UK alone, the net emission of CO2 in 2015 was 404 million tonnes. There is a significant question of where can we put it all even if we capture it, with current suggestions including pumping it underground in to empty oil and gas fields.

“The E. coli solution we have found isn’t only attractive as a carbon capture technology; it converts it into a liquid that is stable and comparatively easily stored,” said Professor Sargent.

“Formic acid also has industrial uses, from a preservative and antibacterial agent in livestock feed, a coagulant in the production of rubber, and, in salt form, a de-icer for airport runways. It could also be potentially recycled into biological processes that produce CO2, forming a virtuous loop.”

Last week US researchers announced they had developed a chemical process for producing useful products, including electricity, from fossil fuels such as shale gas, coal and biomass without emitting CO2. 

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