Bacteria engineered to convert carbon dioxide into useful chemicals

The bacteria are known to break down lactose to make yogurt and beer. Now researchers led by Northwestern University and the LanzaTech they exploited bacteria to break down waste carbon dioxide (CO2), obtaining precious industrial chemicals. In a new pilot study, researchers selected, engineered and optimized a bacterial strain and then successfully demonstrated its ability to convert CO2 into acetone and isopropanol (PAH).

This new gas fermentation process not only removes greenhouse gases from the atmosphere, but also avoids the use of fossil fuels, which are typically needed to generate acetone and PAHs. After performing the life cycle analysis, the team found that the carbon-negative platform could reduce greenhouse gas emissions by 160% compared to conventional processes, if widely adopted.

“The acceleration of the climate crisis, combined with rapid population growth, poses some of the most pressing challenges for humanity, all related to the relentless release and accumulation of CO2 throughout the biosphere,” said Michael Jewett of Northwestern, senior co-author of the study. “By harnessing our ability to collaborate with biology on a sustainable and renewable basis, we can begin to harness the available CO2 to transform the bioeconomy.”

Jewett is Walter P. Murphy Professor of Chemical and Biological Engineering at Northwestern’s McCormick School of Engineering and director of the Center for Synthetic Biology. He co-led the study with Michael Koepke and Ching Leang, both LanzaTech researchers.

Acetone and IPA are used in many industries, with a combined global market exceeding $ 10 billion. Widely used as a disinfectant and antiseptic, IPA is the basis for one of two disinfectant formulas recommended by the World Health Organization, which are highly effective in killing the SARS-CoV-2 virus. And acetone is a solvent for many plastics and synthetic fibers, polyester resin, cleaning tools and even for nail polish remover.

While these chemicals are incredibly useful, they are generated from fossil resources, leading to significant CO2 emissions. To produce these chemicals more sustainably, the researchers developed a new gas fermentation process. They started with Clostridium autoethanogenum, an anaerobic bacterium designed at LanzaTech. Then, the researchers used synthetic biology tools to reprogram the bacterium to ferment CO2 thereby producing acetone and PAHs.

The Northwestern and LanzaTech teams believe the developed strains and fermentation process will translate to industrial scale. The approach could also potentially be applied for the production of other valuable chemicals.

“This discovery is a major step forward in averting a climate catastrophe,” said Jennifer Holmgren, CEO of LanzaTech. “Today, most of our chemical raw materials derive exclusively from fossil resources such as oil, natural gas or coal. Acetone and IPA are two examples with a combined global market of $ 10 billion ”. The methods of producing acetone and PAHs through bacteria will accelerate the development of other new products by closing the carbon cycle.