Deep Sea Bacteria Releases Excess Carbon to the Oceans, Atmosphere

Researchers from the University of Minnesota discovered that deep-sea bacteria dissolve carbon-containing rocks, emitting excess carbon that settles in the ocean and the atmosphere.

Findings to Help Estimate Carbon Dioxide Levels in Earth's Atmosphere

The study results will help researchers to better assess the amount of carbon dioxide in the Earth's atmosphere, which drives global warming.

Findings of the study, "Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps," has been published in The ISME Journal: Multidisciplinary Journal of Microbial Ecology, a peer-reviewed scientific journal part of the Nature family of publications and the official journal of the International Society for Microbial Ecology (ISME).

"If CO2 is being released into the ocean, it's also being released into the atmosphere because they're constantly interchanging gases between them," said first author Dalton Leprich, a Ph.D. student in the University of Minnesota's Department of Earth and Environmental Sciences, as quoted in the study. "While it's not as big of an impact as what humans are doing to the environment, it is a flux of CO2 into the atmosphere that we didn't know about. These numbers should help us home in on that global carbon budget."

The researchers started analyzing sulfur-oxidizing bacteria, which is a group of microbes that utilize sulfur as an energy source, in the ocean floor's methane seeps. Similar to deep-sea coral reefs, these methane seeps contain limestone that confines large amounts of carbon, with the sulfur-oxidizing microbes settling on top of these rocks.

Bacteria Dissolves Carbon-Containing Limestone

After observing corrosion patterns and holes in the limestone, the researchers discovered that the sulfur-oxidizing process had bacteria creating an acidic reaction dissolving the rocks. This would then release carbon from the limestone.

"You can think of this like getting cavities on your teeth," Leprich said in the study. "Your tooth is a mineral. Some bacteria live on your teeth, and your dentist will typically tell you that sugars are bad for your teeth. Microbes are taking those sugars and fermenting them, and that fermentation process is creating acid and that will dissolve away at your teeth. It's a similar process to what's happening with these rocks."

Researchers are looking at trying out their findings on various mineral types. It could also help scientists utilize dissolution features, such as holes, crevices, or other proof of bacteria dissolving rocks, to search for life on other planets.

"These findings are but one of the many examples of the important and understudied role that microbes play in mediating the cycle of elements in the planet," said the corresponding author of the study Jake Bailey, a University of Minnesota Department of Earth and Environmental Sciences associate professor.

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