Recycle greenhouse gases with biotechnologies

Recycle greenhouse gases with biotechnologies

05 May 2022

(Nanowerk News) Acetone and isopropanol are important chemicals for industry. They are used to produce materials from jet fuel to solvents to cleaners to plastics. Currently, the industry produces these two chemicals from oil using processes that release carbon dioxide and other greenhouse gases.

Researchers have now developed a new fermentation process that efficiently converts carbon monoxide gases into acetone and isopropanol. Researchers used a combination of genomic analyzes, computer models and optimization of metabolic pathways outside the cells to design bacterial strains. The result is bacteria that convert carbon waste into valuable materials.

Scientists developed a process to convert industrial, agricultural and urban exhaust gases into important chemicals. This process captures more carbon gas than it releases. Scientists call this “carbon-negative” bioproduction. The new approach enables industry to produce plastics, fuels and other chemicals in a more sustainable way. This approach will also lead to faster development of efficient cell-based production methods. This will reduce greenhouse gas emissions and other environmental impacts of industrial activity. Schematic representation of the interdisciplinary approach used to develop a new carbon-negative pathway for the production of the basic chemicals acetone and isopropanol, providing a model for the accelerated development of new biological processes. (Image courtesy of Liew, F., et al., Carbon-negative production of acetone and isopropanol by gas fermentation on an industrial pilot scale. Nature Biotechnology 40 (3) (2022))

Researchers from Oak Ridge National Laboratory, LanzaTech Inc., Northwestern University and University of Tennessee used an interdisciplinary approach to optimize strains of the bacterium. Autoethanogenic Clostridium maximize the production of acetone and isopropanol from exhaust gases.

Scientists first searched the genomes of a collection of industrial strains for higher enzymes that produce acetone and isopropanol. They tested multiple combinations of those enzymes in these bacteria to select the most efficient engineered sets of enzymes.

The team then further optimized those metabolic pathways using computational modeling, cell-free enzyme screening, and proteomic analyzes to identify metabolic bottlenecks and competing pathways.

Finally, they adapted the process for high speed and stability and increased the crops to 120 liters for continuous conversion of the exhaust gases to acetone or isopropanol.

Applying a life cycle analysis, the team demonstrated that this bioproduction approach reduced greenhouse gas emissions by 165% compared to fossil fuel-based processes. While the production of these two chemicals from fossil fuels releases carbon gas, this biological process captures the carbon.

These results show that the engineered acetogenic bacteria enable the production of sustainable, highly efficient and highly selective chemicals. This multi-faceted optimization of the strain and process demonstrates the potential for continued advances in biotechnology to shift industrial practices towards more sustainable methods.

Publications

Liew, F .., et al., Carbon-negative production of acetone and isopropanol by gas fermentation on an industrial pilot scale. Biotechnology of nature 40 (3), 335–344 (2022). [DOI: https://www.nature.com/articles/s41587-021-01195-w ]

Pavan, M., et al., Advances in metabolic engineering of autotrophic biocatalyst systems that fix carbon monoxide towards a circular economy. Metabolic engineering 71, 117-141 (2022) [DOI: https://doi.org/10.1016/j.ymben.2022.01.015]

Fackler, N., et al., Stepping on Gas Towards a Circular Economy: Accelerating the Development of Carbon-Negative Chemical Production from Gas Fermentation. Annual review of chemical and biomolecular engineering 12, 439-470 (2021). [DOI: 10.1146/annurev-chembioeng-120120-021122]

Rasor, B., et al., Towards a sustainable and cell-free bioproduction. Current opinion in biotechnology 69, 136-144 (2021). [DOI: 10.1016/j.copbio.2020.12.012]

Köpke, M. & Simpson, S., Product pollution: recycling of carbon “above ground” by fermentation of gas ” Current opinion in biotechnology 65, 180-189 (2020). [DOI: 10.1016/j.copbio.2020.02.017]

Karim, A., et al., Modular cell-free expression plasmids to accelerate biological design in cells. Synthetic biology 5 (1), ysaa019 (2020). [DOI: 10.1093/synbio/ysaa019]

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