By replacing the natural enzyme plants use to convert carbon dioxide into organic compounds such as sugar, a team of biochemists have reportedly found a way to allow plants to remove the greenhouse gas from the atmosphere far more efficiently, according to a new study.
In a paper published Friday in the journal Science, Tobias Erb from the Max Planck Institute for Terrestrial Microbiology in Marburg, Germany and his colleagues described how they managed to reverse-engineer processes such as photosynthesis, through which plants convert CO2 in such organic compounds as sugar, and find a way to make the process exponentially faster.
What they did, Popular Mechanics and the Christian Science Monitor explained, was construct a synthetic biological pathway in vitro that is based on a new CO2-fixing enzyme that is almost 20 times faster at capturing carbon dioxide than its most efficient natural equivalent. This discovery could make the process 25% more energy efficient and up to three times faster, they noted.
“We actually have taken our inspiration from nature itself,” Erb told the Monitor, adding that “a lot of bacteria and microorganisms that can also fix CO2” using different biological mechanisms than plants, “which tells us that nature itself has the potential to find other ways to fix CO2.”
Findings suggest that CO2 fixation processes can be improved
According to Popular Mechanics, plants and algae currently absorb approximately 350 gigatons of carbon dioxide each year through a series of chemical reactions known as the Calvin cycle – a series of molecular transformations that turns simple CO2 molecules into complex sugars such as glucose. The problem, the Monitor said, it that humans emit four times that much CO2.
Looking to improve upon the process, Erb’s team developed a new carbon-absorbing cycle based on the Calvin cycle that they have dubbed the CETCH cycle. They sequenced and synthesized 17 total enzymes from nine different organisms and came up with a proof-of-principle CO2-fixation pathway that can more efficiently remove carbon dioxide from Earth’s atmosphere.
The researchers used a new enzyme known as ECR, which is several times at removing carbon from the air than the naturally-occurring RuBisCO enzyme. Their new carbon fixation process, Popular Mechanics explained, requires 11 steps to convert the atmospheric CO2 into a chemical compound called glyoxylate, and found that it was much faster under laboratory conditions.
Erb admitted that it is difficult to know how much quicker the CETCH cycle would be in nature, since it requires fewer steps and used enzymes that work more quickly than the Calvin cycle, but he speculates that it may be between two and three times faster. Furthermore, the glyoxylate that is produced by the process could be converted for use in biofuels or antibiotics, he added.
“This is an exciting outcome for systems biology, demonstrating that novel theoretical CO2 fixation pathways can indeed be realized,” Lisa Ainsworth, a plant biologist at the University of Illinois at Urbana-Champaign who was not involved in the study, told the Monitor via email. “Whether this pathway or another novel pathway could be engineered into plants is an open question, but this research certainly advances the possibility.”
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