Removing CO2 from the atmosphere could help with climate change, and there’s now a new biological method in the making to achieve this. Researchers have developed a new turbo-charged version of a metabolic pathway for fixing CO2, which is 20% more efficient than in plants.

As described in an article just published in Science, a German research team has shown the feasibility of fixing COvia its improved version of the dark cycle of photosynthesis. The pathway, made of 17 enzymes from 9 different organisms, outperforms the natural pathway in plants and could mitigate climate change. The research started out at ETH Zuricha key institution for emerging Biotechs in the area, and now goes on at the Max Planck Institute in Marburg, Germany.

The new metabolic pathway, CETCH, was designed to give the Calvin cycle, part of the photosynthesis in plants, a run for its money. The team leader of this project, Tobias Erb, had succeeded in isolating a very efficient CO2-fixing enzyme, which is faster and more accurate than the RuBisCo enzyme occurring naturally in plants. However, simply replacing the enzyme in the original Calvin cycle did not work, as the enzymes were not compatible. Consequently, there was a need to build an artificial pathway.


Figure 1: The CETCH metabolic pathway.

From large databases of known enzymes, researchers picked a few dozen candidates which could perform the required tasks. Then they spent two years combining enzymes in the laboratory to test their efficiency as a system. The 17 enzymes that made the final cut include 3 designer enzymes, which are one of the key challenges of synthetic biology.

The main goal of this work is to create, down the line, an efficient way to convert CO2 into useful chemical compounds. Using CO2 as feedstock is a popular idea, with other projects like EnobraQ, but this is is the first time a synthetic CO2-fixing cycle is developed.

While the pathway has still only been tested in vitro, it could be transferred to bacteria or algae to produce a wide range of products, as in biorefineries. A major selling point for using CO2 as a raw material is the reduction of the environmental impact, potentially even helping to remove the excess of this greenhouse gas in the atmosphere. In this interview about his work, Erb is careful with the impact of this designer pathway and the need to consider the emission reduction. Nevertheless, a CO2-based biotechnology can definitely be an important part of a greener future.

Tobias Erb talks about this synthetic pathway…

Feature Image Credit: mediomix / MPI for Terrestrial Microbiology

Figure 1 Credit: Schwander et al. (2016) A synthetic pathway for the fixation of carbon dioxide in vitro. Science (doi: 10.1126/science.aah5237)

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