A team of scientists from LanzaTech, Northwestern University, and the Department of Energy’s Oak Ridge National Laboratory have developed carbon capture technology that harnesses emissions from industrial processes to produce acetone and carbon dioxide. isopropanol, known as IPA. These widely used chemicals are the basis for thousands of products, from fuels and solvents to acrylic glass and fabrics.
The carbon-negative platform uses microorganisms as tiny but powerful factories that convert carbon from agricultural, industrial and societal waste streams into useful chemicals. The process recycles carbon that would otherwise be released as greenhouse gases that accelerate climate change. In the race to net zero emissions, this technology is a step towards a circular carbon economy that can replace products made from fossil resources.
Researchers relied on LanzaTech technology to develop an efficient new process that converts waste gases, such as heavy industry emissions or syngas generated from biomass, into acetone or IPA, to the using an artificial bacteria called Clostridium autoethanogenum, Where C. automatic. Their methods, including a pilot-scale demonstration and life-cycle analysis demonstrating economic viability, are published in the magazine Natural biotechnology.
“This bioprocess offers a sustainable alternative to current production pathways for these critical chemicals, which currently rely on fresh fossil feedstocks and result in significant toxic waste,” said Jennifer Holmgren, CEO of LanzaTech. “We can reduce greenhouse gases by more than 160%, achieve carbon negative output, and trap carbon that would have ended up in the atmosphere.”
LanzaTech is currently developing this technology, which can be inserted into their existing systems and deployed for use around the world.
“Synthetic biology can be a powerful tool in the quest to advance decarbonization and tackle climate change,” said Stan Wullschleger, associate director of the ORNL lab. “Our scientists harness world-class capabilities, working closely with industry to harness biological systems to produce valuable fuels and chemicals that support a thriving national bioeconomy.”
The research began at LanzaTech, where scientists had previously commercialized a process using VS. car strains that can produce ethanol, a common biofuel, from carbon emissions. Identifying the best enzymes for the production of acetone and IPA and designing microbial strains to achieve efficient and high-yield carbon-to-chemical conversion has been a complex scientific challenge.
Scientists used a three-pronged approach including innovations in pathway screening, strain optimization and process development. Initially, LanzaTech screened nearly 300 strains for enzymes that may be useful in acetone and IPA production pathways. After identifying useful strains, the scientists built a combinatorial DNA library – the largest ever for this class of microbes – to find enzyme variants that optimized acetone production.
Further optimization relied on state-of-the-art synthetic biology tools, including cell-free prototyping by Northwestern University, advanced modeling by LanzaTech, and molecular analyzes by ORNL.
“Oak Ridge has very unique capabilities in terms of DNA sequencing, systems biology, and various metabolomics and proteomics,” Michael Köpke, LanzaTech’s vice president for synthetic biology, said. “Oak Ridge’s expertise helped us troubleshoot the process to know which steps may be limiting.”
Proteomics, the study of proteins, and metabolomics, the study of small molecules called metabolites, provide a molecular level view of the specific chemicals used and produced by a microbe. Like any organism, when microbes consume or metabolize the substances they need to survive, they produce byproducts. For scientists who manufacture microbes to produce certain substances, these by-products represent bottlenecks.
“Protein and metabolite profiles show where a production bottleneck occurs inside the VS car cell,” said Tim Tschaplinski, head of ORNL’s Biodesign and Systems Biology Section. “We can see what needs to be changed next in the pathways to get more carbon to the product.”
In this case of VS car, ORNL scientists determined that the microbe produced a significant amount of the compound 3-hydroxybutyrate that would require downstream processing and increase processing costs. This compound sits in the middle of a key metabolic pathway where it can move carbon in different directions.
“We look at the enzyme pathways and say, ‘Here’s the block, and there may be a dozen different enzymes in the original collection that might do a better job,'” Tschaplinski said. “Then our partners at Northwestern University express these enzymes in cell-free systems, and we look at what accumulates, which feeds LanzaTech’s advanced computer models.”
The optimization process was enabled by ORNL’s holistic systems biology approach, which gives scientists a more complete view of what’s going on in the cell and how to improve it, Tschaplinski said. “We use one ‘omic to confirm another,” he said. “By looking at the system as a whole rather than just an individual data stream, we can explore different avenues to improve the generation of the desired product.”
“We found that one of the enzymes, in particular, gave a significant boost once we ramped up production,” Köpke said. “And we found that out through a lot of systems biology and proteomics analyzes that were done by Oak Ridge.”
This collaboration is the latest in a long-standing relationship between ORNL and LanzaTech. In 2015, a team of scientists from ORNL and LanzaTech sequence all C. atfor genome, laying the foundation for current research.
Acetone strain and process development, genome-scale modeling, life cycle analysis, and early pilot testing were supported by LanzaTech and the Office of Efficiency’s Bioenergy Technology Office DOE Energy and Renewable Energy. Cell-free prototyping and omics analyzes were funded by the DOE’s Office of Science Biological and Environmental Research Program. DNA sequencing was supported by the Joint Genome Institute, a user facility of the DOE Office of Science.
UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the largest support of basic physical science research in the United States. The Office of Science strives to meet some of the most pressing challenges of our time. For more information, please visit energy.gov/science. –Abby Bower and Kim Askey
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Carbon-negative production of acetone and isopropanol by gas fermentation at industrial pilot scale
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