[Germany] By tinkering with the process that plants use to breathe in carbon dioxide, a team of German scientists has just discovered a far more efficient way to get rid of it. Biochemists led by Tobias Erb at the Max Planck Institute for Terrestrial Microbiology in Marburg, Germany, have developed a new, super-efficient method for living organisms to suck CO2 out of the atmosphere.
Plants, algae, and other organisms turn CO2 into fuel. Erb and his colleagues reengineered this process, making it about 25 percent more energy efficient and potentially up to two or three times faster. The study appears in Science.
Plants and algae are already pretty damn good at getting rid of carbon dioxide. Globally, they consume about 350 gigatons of CO2 per year. Almost all of that carbon absorption is done through same chemical process, a series of chemical reactions called the Calvin cycle.
To put it simply, the Calvin cycle is a set of molecular transformations that slowly turns simple three-atom CO2 molecules into glucose, a complex sugar. Plants use it and get by just fine. From an engineering perspective, however, it’s easy to see how life’s Calvin cycle could use a tuneup.
For one things, the process hinges on a specific molecular tool called RuBisCO, which grabs hold of CO2 gas, and forms it into a bigger molecule to get things started. The problem? “RuBisCO is slow,” and, like a puttering car, “it backfires often, meaning about every 5th attempt RuBisCO will mix up CO2 with oxygen gas,” says Erb. Grabbing the wrong gas slows down the carbon absorbing process.
Erb designed a carbon-absorbing cycle much like the Calvin cycle, but which relies on a much faster and more efficient molecular tool. The tool is an enzyme called ECR, which does the same job as RuBisCO but around 9 times faster. Erb calls his new process the CETCH cycle.
Erb’s new CETCH cycle requires 11 steps to turn airborne CO2 into a chemical called glyoxylate. Each of these 11 steps requires a molecule-transforming enzyme, and each enzyme was carefully selected from the library of 40,000 known enzymes. “Some enzymes are found in the human body, and gut bacteria,” says Erb, others are taken “from plants, and microbes that live in the oceans and on the surface of plants.”
Erb and his colleagues tested their CETCH cycle in their lab. To oversimplify matters, they mixed together all their enzymes with some chemical fuel and calculated how much CO2 was being pulled out of the air. They found that their CETCH cycle is about 25 percent more energy-efficient than the Calvin cycle plants and algae use.
“Right now the entire chemical industry is based on fossil fuels, whether you’re talking about making plastics or textiles, antibiotics or your mobile phone,”
Erb says that it’s hard to estimate how much faster the CETCH cycle would be compared to Calvin if it was working in an organism, but because it uses less steps and faster enzymes than the Calvin cycle, it could potentially be up to two or three times as quick. “But right now the speed is speculation. It could even be slightly slower,” Erb says. They just don’t know for sure.
Erb says that while the weird glyoxylate chemical the CETCH cycle produces is largely useless on its own, it can actually be easily transformed into a wide variety of different chemicals that have uses, including biofuels and antibiotics.
Erb hopes that one day the CETCH cycle could be genetically engineered into living organisms, helping them more rapidly reduce atmospheric CO2 while producing useful materials. But it’s certainly not an easy task and one that would require a lot more study, as the scientists have no idea what might happen their 11 steps when placed inside the chaotic system of a living cell.
“But you can imagine one day producing something like an artificial leaf, or another hybrid system where photovoltaic solar cells could provide energy for algae or bacteria living under them, which are using this CETCH cycle to adsorb CO2 and produce useful chemicals,” he says.
While Erb argues that this kind of technology is decades away—at the closest—it could provide a radical environmental and economic shift.
“Right now the entire chemical industry is based on fossil fuels, whether you’re talking about making plastics or textiles, antibiotics or your mobile phone,” he says. Erb says that instead of adding to Earth’s CO2 burden, industrial chemical production using these types of organisms could be actively fighting climate change while creating useful products.
View original article at: New way of transforming CO2 is more efficient than what plants do