Methane-eating microbes found in Illinois aquifer

Jul 25, 2013 by Louise Lerner

Methane-consuming microbes live deep underground in pristine aquifers, according to a study by the U.S. Department of Energy's Argonne National Laboratory and the Environmental Protection Agency. This type of organism, which can consume methane in the absence of oxygen, has previously been found only in marine sediments.

The team studied the microbial community living deep underground in the Mahomet Aquifer, a multi-trillion-gallon subterranean reservoir that provides drinking water to residents in central Illinois. It is uncontaminated by human activity.

"The problem we set out to address is that we didn't really have a good sense of what the microbial community in a pristine aquifer looks like," said Argonne postdoctoral fellow Ted Flynn. Microbes play an integral role in the of groundwater, and scientists are still teasing out their role in the .

The Mahomet aquifer is protected by its glacial ancestry; growing and receding glaciers laid alternating blankets of fine glacial "till" and coarser gravel. When humans spill something toxic aboveground, the silt and clay in the till layer act as a filter to delay its passage to the clean water below.

It's also a natural hotbed of . "In some parts of the Mahomet, the groundwater is so charged with methane that when you pump it to the surface, bubbles of the gas effervesce out—like champagne—and can be ignited," Flynn said.

Flynn and his colleagues knew that most existing studies on simply catalogued the in a sample of water pulled up from the aquifer. But they thought this method might not represent what lives in the solid lining the aquifer's walls and layers. So they lowered clean bags filled with sterile sediment down into the aquifer and let the microbes colonize them over three months.

This meant the scientists were sampling only live microbes that had been active in the past three months. By comparison, a sample of sediment directly lifted from the walls through a DNA sequencer would pull up DNA fragments from long-dead microbes, which wouldn't give a clear picture of the current microbe population.

Inside the aquifer, they discovered an odd organism that had previously only been noted along deep-sea vents on the ocean floor: tiny microorganisms, called anaerobic methane oxidizers, that consume methane even in the absence of oxygen. They are archaea, which make up one of the three evolutionary domains of life along with bacteria and eukaryotes, which includes humans. Anaerobic methane oxidizers were first found living along the ocean floor near deep-sea vents, living off the methane bubbling out of the vents. "This is the first time we've seen them in terrestrial habitats," Flynn said.

These organisms turn methane into bicarbonate, a compound that doesn't leak into the atmosphere but stays dissolved in water. (You've probably seen bicarbonate: it sometimes reacts with metal to leave a flaky white residue on drinking fountains, Flynn said.)

Explore further: NASA air campaigns focus on Arctic climate impacts

Related Stories

Paired microbes eliminate methane using sulfur pathway

Jan 17, 2008

Anaerobic microbes in the Earth's oceans consume 90 percent of the methane produced by methane hydrates – methane trapped in ice – preventing large amounts of methane from reaching the atmosphere. Researchers now have ...

Microbes surviving deep inside oceanic crust

Mar 15, 2013

(Phys.org) —A new study shows for the first time that microorganisms are thriving deep within the oceanic crust under the sea floor, and hence far from light or oxygen.

Oil-eating microbe communities a mile deep in the Gulf

Jul 09, 2013

The Deepwater Horizon explosion on April 20, 2010, caused the largest marine oil spill in history, with several million barrels of crude oil released into the Gulf of Mexico over the course of three months. ...

Life discovered on dead hydrothermal vents

Jan 25, 2012

Scientists at USC have uncovered evidence that even when hydrothermal sea vents go dormant and their blistering warmth turns to frigid cold, life goes on.

Recommended for you

NASA air campaigns focus on Arctic climate impacts

44 minutes ago

Over the past few decades, average global temperatures have been on the rise, and this warming is happening two to three times faster in the Arctic. As the region's summer comes to a close, NASA is hard at ...

NASA image: Smoke wafts over the Selway Valley in Idaho

48 minutes ago

Smoke from the fires in the Selway Complex is wafting into the Selway River valley in this image taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite on September ...

NASA HS3 instrument views two dimensions of clouds

17 hours ago

NASA's Cloud Physics Lidar (CPL) instrument, flying aboard an unmanned Global Hawk aircraft in this summer's Hurricane and Severe Storm Sentinel, or HS3, mission, is studying the changing profile of the atmosphere ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

SteveL
not rated yet Jul 25, 2013
It's also a natural hotbed of methane production. "In some parts of the Mahomet, the groundwater is so charged with methane that when you pump it to the surface, bubbles of the gas effervesce out—like champagne—and can be ignited," Flynn said.
This has been known for at least a century, but modernly it has been popularized as being due to hydraulic fracturing. Not that "fracking" may not be exacerbating the situation in some areas, but methane has been present in some water supplies long before the practice of fracking started.

Bicarbonates are important to us biologically, but by binding up oxygen these little critters may not be the most beneficial to us.

This indicates another type of life we may eventually find on other planets.