UAF researchers discover sulfolane-eating microbe

December 13, 2019

University of Alaska Fairbanks scientists presented their work at the American Geophysical Union’s fall meeting in San Francisco this week. This article is part of a series highlighting UAF research from the world’s largest Earth and space science meeting.

University of Alaska Fairbanks research has identified a microbe that can break down the industrial chemical sulfolane, a discovery that could boost efforts to treat contaminated groundwater.

The chemical has been scrutinized by scientists and health officials since it was discovered in 2009 in groundwater surrounding an oil refinery in the city of North Pole. Since then, it has been detected in a 2.5-by-4-mile underground plume of contaminated water in the area.

UAF researchers were approached by the Alaska Department of Environment Conservation to study whether microbes exist in the North Pole aquifer that can biodegrade the chemical.

They found that some can, but only under the right circumstances.

“There were microbes present that could break it down very rapidly, but without oxygen they didn’t break it down at all,” said Mary Beth Leigh, a professor at UAF’s Institute of Arctic Biology. She discussed the findings at the fall meeting of the American Geophysical Union on Friday, Dec. 13.

Leigh, Ph.D. student Chris Kasanke, and David Barnes, a UAF professor of civil and environmental engineering, studied core samples and groundwater from the contaminated area. Only the samples that were exposed to oxygen showed biodegradation of sulfolane.

Isotope-labeling studies showed that just a single microbe, a type of bacteria from the genus Rhodoferax, was responsible for degrading the chemical. Researchers found the microbe is widespread in the North Pole aquifer, and is present in about 70 percent of wells tested.

However, Rhodoferax probably won’t be part of a solution for decontaminating North Pole groundwater, Leigh said. Although injecting air into the aquifer (known as air sparging) could stimulate the microbe’s ability to break down sulfolane, the plume has become too large to make that solution practical. Without the added oxygen, Rhodoferax seems to remain inactive underground.

However, the findings could provide a remedy for more concentrated spills, she said.

“One of the more positive things we’ve gained from this study is that things like air sparging can be helpful,” she said. “You just need to catch it early.”