On Earth, massive amounts of methane are trapped inside white, cage-like chemical structures. These deposits are primarily present in permanently frozen polar regions in addition to on the seafloor, but the important thing here is that they don’t seem to be specific to our planet. Similar reservoirs are known to exist on bodies across the solar system — from planets and their moons to comets zipping by. And though scientists think such deposits ultimately influence the composition of those worlds’ ocean waters and atmospheres it stays an open query whether or not they arise from biological processes. Many experts have long wondered how those methane cages remain stable under high-pressure ocean water conditions.
Now, a team of researchers studying considered one of these methane deposits — plucked from the seafloor off the coast of Oregon — have discovered a previously unknown class of proteins that seems to play a very important role in stabilizing the structure of the deposits.
“We wanted to grasp how these formations were staying stable under the seafloor, and precisely what mechanisms were contributing to their stability,” Jennifer Glass, who’s a professor within the School of Earth and Atmospheric Sciences at Georgia Institute of Technology and a co-author of the brand new study, said in a statement. “That is something nobody has done before.”
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On Earth, solid ice-like deposits referred to as methane clathrates form when microorganisms in ocean waters convert organic materials, like remnants of plankton, into methane, which then gets trapped in cages. These deposits transform into gas over time and rise upward. During this process, quite a lot of organisms start feasting on the methane. Eventually, the chemical is released into the atmosphere. But in regions just like the Arctic, where water is warming faster than the remainder of the planet, large amounts of methane escape ocean waters before those biological communities can eat them.
“These deep microbes encode genes which might be different from any found on the Earth’s surface,” Glass had previously said when the research had begun with support from the NASA Exobiology Program. “This project gives us the chance to unravel microbial survival strategies at extreme conditions, understand the roles of microbes within the fate [of] methane in hydrate reservoirs, and expands our research capability.”
To higher understand methane clathrates, researchers behind the brand new study identified the genes of the proteins present within the sediment. Then, the proteins were recreated within the lab for further evaluation. To check those proteins, the team also produced methane clathrates within the lab by recreating the high pressures and low temperatures found on the seafloor. A singular pressure chamber mimicking seafloor conditions was built from scratch and used to measure how much gas the clathrate consumed in a certain time, which shed insight on how quickly it formed, in line with the brand new study.
Results showed a category of proteins called the bacterial clathrate-binding proteins (CbpAs) influenced the expansion of clathrate by interacting directly with its structure. Proteins with antifreeze characteristics like people who help fish survive in colder temperatures stabilized the clathrate structure, scientists say.
“We were so lucky that this actually worked, because though we selected these proteins based on their similarity to antifreeze proteins, they’re completely different,” Abigail Johnson, a postdoctoral researcher on the University of Georgia who had formed methane clathrates within the lab for the brand new study, said in a recent statement. “They’ve the same function in nature, but achieve this through a totally different biological system, and I feel that basically excites people.”
Elsewhere within the solar system, previous research has suggested methane on Mars originates from hydrothermal reactions.
On Titan, which is Saturn‘s largest moon, scientists think the gas originated from its constructing blocks for the reason that early solar system. Saturn’s moon Enceladus and Jupiter‘s Europa, arguably the present best places to go looking for all times, are thought to host methane clathrates as well.
Findings from the brand new study suggest that if microbes exist on other worlds, they could create similar molecules to create and stabilize methane clathrates, which in turn affects the composition of ocean waters and the atmospheres of those worlds.
Thus, to search out alien life, possibly we’d like to follow the methane clathrate trail.
The research is described in a paper published last month within the journal PNAS Nexus.