Discovery of CO2-absorbing bacteria in Missouri bolsters wetlands’ importance in combating climate change
Although it receives less attention than the vast swaths of trees and plants absorbing carbon dioxide in the Amazon, a little-known type of bacteria found in wetlands across the United States — including here in Missouri — may be just as vital to the fight against climate change.
That’s the argument researchers at Washington University in St. Louis are making after publishing a study showing that wetland-dwelling microbes called photoferrotrophs are highly effective at absorbing carbon dioxide.
Separately from the study, the researchers also recently discovered samples of photoferrotrophs in a protected wetland in West Alton, just outside St. Louis. The implications of these combined findings have spurred a flurry of interest in the bacteria, both from other scientists and government agencies.
Photoferrotrophs thrive in oxygen-deprived environments, like waterlogged wetlands, where they feed on iron as a source of the electrons they need to conduct photosynthesis. During photosynthesis, they absorb planet-warming carbon dioxide and lock it away as carbon, just like any photosynthetic plant.
Photoferrotrophs are also likely far more prevalent than previously thought, explained Arpita Bose, an associate professor of biology at Washington University, who led the study.
“Everywhere we’re looking, we’re finding these organisms,” she said. “Right now, we are just scratching the surface.”
Past research on wetlands’ carbon sequestration — the long-term storage of carbon in natural features like plants and soil — has focused on coastal saltwater wetlands, such as those in Woods Hole, Massachusetts, where Bose first studied samples of photoferrotrophs in 2015. But more recent studies have found that freshwater, inland wetlands hold almost 10 times more carbon.
Carbon sequestration plays a key role in moderating the Earth’s climate. When wetlands and forests are destroyed, they release this stored carbon in the form of carbon dioxide, the greenhouse gas most responsible for climate change.
At a time when concentrations of atmospheric carbon dioxide are higher than at any point in the last 800,000 years, due in large part to human activities like deforestation, Bose’s findings underscore the need to preserve ecosystems like wetlands.
While it is still difficult to quantify just how widespread photoferrotrophs are and how much carbon dioxide they absorb in comparison to plants, Bose said she is confident they’re doing it on a huge scale.
“I would venture to say that they’re very common, and my guess would be that these organisms are sequestering quite a lot of carbon,” she said, adding that photoferrotrophs may even be abundant outside of wetlands in deep layers of soil in the earth’s crust.
So far, Bose’s research on photoferrotrophs, which are difficult to keep alive in a lab environment, has largely focused on convincing the scientific community that they are in fact photosynthetic.
But with that feature now established, scientists and government agencies are looking to quantify photoferrotrophs’ impact on the climate and their implications for conservation efforts.
Bose said that since her research team published their paper in May, they have been contacted by agencies such as the United States Fish and Wildlife Service, the Missouri Department of Conservation and Missouri Department of Natural Resources. The agencies are interested in forming a consortium to better understand photoferrotrophs’ relation to climate change.
It’s possible, she added, that the carbon dioxide-absorbing bacteria could be reproduced at a commercial scale as a way to counter climate change, given the abundance of the materials they need to survive and grow.
“We can grow vats of this stuff,” she said.
For now, though, the scientific findings regarding photoferrotrophs at least point to the need for a broader understanding of the vital role natural ecosystems like wetlands play in combating the climate crisis.
They also reveal yet another important function of wetlands, which already provide an array of environmental and societal benefits, such as curbing flooding and acting as natural water purifiers. In Missouri, 87% of the state’s original wetlands have been destroyed since the Revolutionary War, and wetlands are disappearing globally three times faster than forests are.
“[Photoferrotrophs] have always been here and they’re doing so much for us, we just don’t appreciate it,” Bose said. “And with no appreciation, we don’t understand — if we hurt an ecosystem and we lose these organisms — just how bad things could be.”
Mark Ossolinski is a graduate student studying public policy reporting at the Missouri School of Journalism.