The mysterious methane exists in the seabed, in permafrost, and even on other planets?

Studying Earth's methane could inform the search for extraterrestrial life in our solar system

Methane clathrates may exist on the moons of Saturn and Jupiter, and fortunately, they also exist on Earth.

Methane clathrates have been found in sediments off the Oregon coast. A German research vessel discovered the hydrates in the surface layer of the seafloor, about 4,000 feet below the ocean's surface.

(Image source: Wusel007 via Wikimedia Commons)

On Earth, vast quantities of methane are trapped in white, cage-like chemical structures. These deposits are found primarily in deep permafrost and on the ocean floor, but the key is that these substances aren't just found on Earth. Similar deposits exist throughout the solar system, from the planets and their moons to comets zipping by. While scientists believe these deposits ultimately influence the composition of these worlds' oceans and atmospheres, whether they come from biological processes remains an open question. What has long puzzled many experts is how these methane cages remain stable in the high-pressure conditions of seawater.

Now, a team of researchers has extracted a methane deposit from the seafloor off the coast of Oregon and discovered an entirely new protein that appears to play an important role in stabilizing the sediment's structure.

"We wanted to understand how these formations remain stable on the seafloor and what mechanisms contribute to their stability," Jennifer Glass, a professor in Georgia Tech's School of Earth and Atmospheric Sciences and co-author of the new study, said in a statement. "This is something that no one has done before."

On Earth, solid, ice-like deposits called methane clathrates form when microbes in seawater convert organic matter, like plankton remnants, into methane. Over time, these deposits turn into a gas and rise upward. During this process, a variety of organisms begin to feed on the methane. Eventually, the chemical is released into the atmosphere. But in areas like the Arctic, where the water is warming faster than anywhere else on Earth, large amounts of methane are escaping from seawater before biological communities can consume it.

"These deep microbes carry genes unlike anything found on Earth's surface," said Glass, who began the research with support from NASA's Astrobiology Program. "This project gives us the opportunity to uncover strategies for survival in extreme conditions, understand the role of microbes in methane production in hydrate deposits, and expand our research capabilities."

To better understand methane clathrates, the researchers in the new study identified the genes for proteins present in the sediments. These proteins were re-synthesized in the lab to facilitate further analysis. To test these proteins, the team also created methane clathrates in the lab by recreating the high pressures and low temperatures of the seafloor. According to the new study, a unique pressure chamber that mimics the conditions on the seafloor was built from scratch and used to measure how much gas the clathrate consumes in a given time, which helps understand how quickly it forms.

The results suggest that a class of proteins called "bacterial inclusion complex binding proteins" influence the growth of the inclusion complex by interacting directly with its structure. Proteins with antifreeze properties, such as those that help fish survive cooler temperatures, stabilize the inclusion complex's cage structure, the scientists said.

“We were very lucky that this worked because, even though we chose these proteins based on their similarity to antifreeze proteins, they are completely different,” Abigail Johnson, a postdoctoral researcher at the University of Georgia who made the methane clathrates in her lab for the new study, said in a recent statement. “They have similar functions in nature, but they are accomplished by completely different biological systems. I think that’s what’s really getting people excited.”

Elsewhere in the solar system, previous studies have suggested that methane on Mars originates from hydrothermal reactions.

On Saturn's largest moon, Titan, scientists think the gas originated from the building blocks of the early solar system. Saturn's moons Enceladus and Jupiter's Europa, considered the best places to look for life, are also thought to contain methane clathrates.

The new study's findings suggest that if microbes exist on other worlds, they could potentially make similar molecules to create and stabilize methane clathrates, which in turn could influence the composition of the ocean water and atmosphere on those worlds.

So to find extraterrestrial life, perhaps we need to follow the trail of methane clathrates.

The research was published in the August 2023 issue of the journal PNAS Nexus.

BY:Sharmila Kuthunur

FY: Continent

If there is any infringement of related content, please contact the author to delete it after the work is published.

Please obtain authorization for reprinting, and pay attention to maintaining integrity and indicating the source