E. coli engineered to grow on carbon dioxide and formic acid as sole carbon sources

E. coli engineered to grow on CO₂ and formic acid as sole carbon sources
Metabolic engineering strategies and central metabolic pathways of the engineered E. coli strain that grows on CO2 and formic acid. Carbon assimilation and reducing power regeneration pathways are described. Engineering strategies and genetic modifications employed in the engineered strain are also described. Credit: Nature Microbiology

Most biorefinery processes have relied on the use of biomass as a raw material for the production of chemicals and materials. Even though the use of CO₂as a carbon source in biorefineries is desirable, it has not been possible to make common microbial strains such as E. coli grow on CO₂.

Now, a metabolic engineering research group at KAIST has developed a strategy to grow an E. coli strain to higher cell density solely onCO₂and formic . Formic acid is a one carbon , and can be easily produced from CO₂ using a variety of methods. Since it is easier to store and transport than CO₂, formic acid can be considered a good liquid-form alternative of CO₂.

With support from the C1 Gas Refinery R&D Center and the Ministry of Science and ICT, a research team led by Distinguished Professor Sang Yup Lee stepped up their work to develop an engineered E. coli strain capable of growing up to 11-fold higher cell density than those previously reported, using CO₂ and formic acid as sole carbon sources. This work was published in Nature Microbiology on September 28.

Despite the by several research groups on the development of E. coli capable of growing on CO₂ and formic acid, the maximum cell growth remained too low (optical density of around 1) and thus the production of chemicals from CO₂ and formic acid has been far from realized.

The team previously reported the reconstruction of the tetrahydrofolate cycle and reverse glycine cleavage pathway to construct an engineered E. coli strain that can sustain growth on CO₂ and formic acid. To further enhance the growth, the research team introduced the previously designed synthetic CO₂ and formic acid assimilation pathway, and two formate dehydrogenases.

Metabolic fluxes were also fine-tuned, the gluconeogenic flux enhanced, and the levels of cytochrome bo3 and bd-I ubiquinol oxidase for ATP generation were optimized. This engineered E. coli strain was able to grow to a relatively high OD600 of 7~11, showing promise as a platform strain growing solely on CO₂ and formic acid.

Professor Lee said, "We engineered E. coli that can grow to a higher cell density only using CO₂ and formic acid. We think that this is an important step forward, but this is not the end. The engineered strain we developed still needs further engineering so that it can grow faster to a much higher density."

Professor Lee's team is continuing to develop such a strain. "In the future, we would be delighted to see the production of chemicals from an engineered E. coli strain using CO₂ and as sole carbon sources," he added.


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Engineered E. coli using formic acid and CO2 as a C1-refinery platform strain

More information: Junho Bang et al. Escherichia coli is engineered to grow on CO2 and formic acid, Nature Microbiology (2020). DOI: 10.1038/s41564-020-00793-9
Journal information: Nature Microbiology

Citation: E. coli engineered to grow on carbon dioxide and formic acid as sole carbon sources (2020, September 29) retrieved 19 October 2020 from https://phys.org/news/2020-09-coli-carbon-dioxide-formic-acid.html
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