The CO2 Wrangler
Chemical biologist is developing enzymatic ways to turn the excess CO2 in our atmosphere into useful stuff
The vast amount of carbon dioxide churning in our atmosphere and warming up the planet has many researchers chasing efficient ways to remove it from the air.
“At the moment, the only thing humans can do is dump it in the ground or the ocean. Or we can trap and sequester it,” says Tobias J. Erb, a synthetic biologist at Max Planck Institute for Terrestrial Microbiology, in Marburg, Germany. Erb has a different strategy: Use bacterial enzymes to pull CO2 from the atmosphere and then convert it into useful carbon-based compounds, such as biofuel or polymers.
As a graduate student, Erb nailed the first step in the process by plucking the world’s fastest and most efficient CO2-fixing enzyme from an ancient purple photosynthetic Proteobacteria called Rhodobacter sphaeroides. The enzyme, crotonyl-CoA carboxylase/reductase (CCR), is nearly 100 times as fast at pulling CO2 out of the atmosphere as the enzyme that plants use.
Plants convert CO2 into useful carbon-based compounds by the gigaton each year, but the enzyme responsible for this transformation, called Rubisco, is not only slow, it’s a bit fickle: About 20% of the time, it chooses to fix oxygen instead of CO2.
Since discovering CCR, Erb has been dissecting the way the enzyme extracts CO2 from the air to make the process more efficient. He’s also assembled an orchestra of 15 enzymes that can work in harmony with CCR to produce basic three-carbon compounds. His goal is to get this system working optimally in a test tube, export it to a bacterial or plant cell, and ramp up the variety and usefulness of products it makes.—Sarah Everts
Research At A Glance
Erb wants to reduce the greenhouse gas CO2 in Earth’s atmosphere with bacterial enzymes and turn it into useful carbon-based compounds. He’s already discovered a CO2-fixing enzyme, called CCR, that can carry out the toughest step: Pull CO2 out of the air and attach it to an organic molecule, crotonyl-CoA. The long-term goal is to build more complicated, useful compounds such as fuel.