Bacteria turns carbon waste into chemicals for fuels, fabric

International researchers have selected, engineered and optimised a bacteria strain to break down waste carbon dioxide (CO₂) and make valuable industrial chemicals — acetone and isopropanol (IPA).

The new gas fermentation process developed by researchers at Northwestern University is said to remove greenhouse gases from the atmosphere without using fossil fuels — which are typically needed to generate acetone and IPA. After performing life-cycle analysis, the team found the carbon-negative platform could reduce greenhouse gas emissions by 160% as compared to conventional processes, if widely adopted.

“The accelerating climate crisis, combined with rapid population growth, pose some of the most urgent challenges to humankind, all linked to the unabated release and accumulation of CO₂ across the entire biosphere,” said Northwestern’s Michael Jewett, co-senior author of the study. He co-led the study with Michael Koepke and Ching Leang, both researchers at LanzaTech.

“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.”

Necessary industrial bulk and platform chemicals, acetone and IPA are found nearly everywhere, with a combined global market topping $10 billion. Widely used as a disinfectant and antiseptic, IPA is the basis for one of the two World Health Organization-recommended sanitiser formulas, which are highly effective in killing the SARS-CoV-2 virus. And acetone is a solvent for many plastics and synthetic fibres, thinning polyester resin, cleaning tools and removing nail polish.

While these chemicals are incredibly useful, they are generated from fossil resources, leading to climate-warming CO₂ emissions.

To manufacture these chemicals more sustainably, the researchers developed a new gas fermentation process. They started with Clostridium autoethanogenum, an anaerobic bacterium engineered at LanzaTech. Then, the researchers used synthetic biology tools to reprogram the bacterium to ferment CO₂ to make acetone and IPA.

“These innovations, led by cell-free strategies that guided both strain engineering and optimisation of pathway enzymes, accelerated time to production by more than a year,” Jewett said.

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

“This discovery is a major step forward in avoiding a climate catastrophe,” said Jennifer Holmgren, LanzaTech CEO. “Today, most of our commodity chemicals are derived exclusively from new fossil resources such as oil, natural gas or coal. Acetone and IPA are two examples with a combined global market of $10 billion. 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.”

The study was supported by the U.S. Department of Energy (DOE) Bioenergy Technologies Office, DOE Office of Science, Biological and Environmental Research Division, Genomic Science, the David and Lucile Packard Foundation and the Camille Dreyfus Teacher-Scholar Program.

Image caption: Synthetic biologists have engineered bacteria to convert carbon waste into valuable chemicals. The carbon-negative approach could contribute to a net-zero emissions economy. Image credit: Justin Muir