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Scientists have developed a synthetic way to absorb CO2 that's way faster than plants

Meet the new photosynthesis.

PETER DOCKRILL
18 NOV 2016
 

The conventional logic when it comes to addressing Earth's dangerously high carbon dioxide (CO2) levels is to figure out ways to make sure we pump less CO2 into the air in the first place.

But plant life also helps to reduce humanity's carbon footprint, sucking up about 25 percent of our carbon emissions to produce fuel for itself during photosynthesis. The only problem is, nature's system for doing this is pretty slow and inefficient, but what if it could be boosted?

 

That's the thinking behind a new study from German researchers, who have developed a synthetic system to incorporate CO2 into organic compounds – called carbon fixation – which is both dramatically faster than nature's method and more energy efficient.

When plants absorb carbon during what's known as the Calvin cycle – the second stage of photosynthesis – an enzyme called RuBisCO helps catalyse the reaction that turns CO2 into glucose, which plants use as an energy source.

The drawback with this system, according to lead researcher Tobias Erb from the Max Planck Institute for Terrestrial Microbiology, is that RuBisCO itself isn't exactly quick, which holds the whole process up.

"RuBisCO is slow," he told William Herkewitz at Popular Mechanics, adding that it's also error-prone.

"[I]t backfires often, meaning about every fifth attempt RuBisCO will mix up CO2 with oxygen gas," he explains, which further slows carbon absorption.

To see if they could engineer a better artificial system, Erb's team sifted through a library of some 40,000 known enzymes from all walks of life.

 

"Some enzymes are found in the human body, and gut bacteria," he says, while others were sourced "from plants, and microbes that live in the oceans and on the surface of plants".

From this massive catalogue, the researchers ended up identifying 17 different enzymes from 9 different organisms, and engineered them into a new 11-step system that effectively recreates the Calvin cycle – but with superior results.

These enzymes, which belong to a group called ECRs, could pave the way for a new kind of organic carbon capture system that's potentially way more effective than the shrub on your window sill.

"ECRs are supercharged enzymes that are capable of fixing CO2 at the rate of nearly 20 times faster than the most widely prevalent CO2-fixing enzyme in nature, RuBisCo, which carries out the heavy lifting involved in photosynthesis," Erb said in a press release.

Given that the process has only been trialled in a test tube so far, it's too early to say how much faster the system could be at capturing atmospheric carbon in the real world.

Erb estimates that it could potentially be up to two or three times as quick as plants, but acknowledges it's all speculation until further research is carried out.

"Thus far, our artificial CO2-fixation cycle is a proof-of-principle," he told Maarten Rikken at ResearchGate. "The transplantation of such a 'new metabolic heart' into living organisms, such as algae or plants is another big challenge."

But if scientists can figure out how to incorporate this synthetic carbon fixation cycle into living plants or some other kind of CO2-absorbing organism, it might one day be a big help in removing these heat-trapping molecules from our atmosphere – and that can only be a good thing.

"This is an exciting outcome for systems biology, demonstrating that novel theoretical CO2 fixation pathways can indeed be realised," plant biologist Lisa Ainsworth from the University of Illinois at Urbana-Champaign, who was not part of the research, told Eva Botkin-Kowacki at The Christian Science Monitor.

"Whether this pathway or another novel pathway could be engineered into plants is an open question, but this research certainly advances the possibility."

You can find out more about the research in the video below:

The findings are published in Science.

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