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World’s first CO2-fixing cycle in a test tube

A team of researchers led by Tobias J. Erb at the Max Planck Institute for Terrestrial Microbiology made the world’s first synthetic biological system that fixes CO2 more efficiently than plants. Plants have been using the enzyme rubisco to turn carbon dioxide into useful carbon compounds for millions of years, but it is slow and “fixes oxygen” instead of  COabout 20% of the time (according to Chemical and Engineering News). The article from Sarah Everts is summarized below.

The steps used to make a synthetic biology system that fixes CO2 more efficiently than plants:

  1. Primary Enzyme Selection. The enzyme crotonyl-CoA carboxylase/reductase was selected as a starting point. It is about 20 times as fast at fixing CO2 as rubisco in plants.  It is the CO2-fixing enzyme from the pink proteo­bacterium named Methylobacterium extorquens.
  2. Additional Enzymes. Researchers selected 16 additional enzymes from nine other life-forms—including humans, plants, and microorganisms—to run the world’s first CO2-fixing cycle in a test tube (Science 2016, DOI: 10.1126/science.aah5237).
  3. Cycle Output. The final output of the newly crafted cycle, named CETCH, is the two-carbon glyoxylate, which could then be converted to industrial products, such as biofuels or pharmaceuticals.

The next step would be to create this system in a living organism, not a desktop test-tube. This is very challenging. The energy-efficient CO2-fixing pathway is a “breakthrough for synthetic biology, and it extends the capabilities for recapturing atmospheric CO2 for use as a carbon feedstock,” say Fuyu Gong and Yin Li at the Chinese Academy of Sciences on the new study (Science 2016, DOI: 10.1126/science.aal1559). Thank you to original source Sarah Everts (Chemical and Engineering News).


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– Keri Kukral @kerikukral

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