Researchers didn't know it until now, but two miles under the sea lies a new sulfate-breathing species, revealing just how little we really know about the ocean, new research shows.
The newly discovered microbe species, which is not yet named or classified, lives in massive aquifers, or networks of channels in porous rock beneath the ocean crust where water continually churns. Amazingly, about one-third of Earth's biomass is believed to exist in these uncharted waters.
While it seems nearly impossible for any organism to survive in sulfate-infested waters so far below the surface, these microbes find a way.
Sulfate, composed of sulfur and oxygen, naturally occurs in seawater, and is used in a range of products including car batteries and bath salts. There are many known microbes that can breathe sulfate and gain energy by reacting it with organic compounds, though they are considered to be some of the oldest organisms on Earth. They can be found in marshes and hydrothermal vents, but beneath the ocean surface is a different story.
"This is the first direct account of microbial activity in these type of environments," lead author Alberto Robador from the University of Southern California (USC) said in a statement, "and shows the potential of these organisms to respire organic carbon."
Robador and his colleagues, along with a team from the University of Hawaii, discovered the new species in the Juan de Fuca Ridge off the coast of Washington. They drilled through two miles of ocean and several hundred feet of sediment to reach the rock where the aquifer flows. However, this was easier said than done as the researchers didn't want to contaminate the environment with regular ocean water.
But eventually, using Circulation Obviation Retrofit Kit (CORK) observatories, which created a seal, they obtained microbe samples, finding that unlike their counterparts, this species lacks the oxygen that's used on land to create the necessary chemical reaction with sulfate.
Instead, these microbes can use sulfate to break down carbon from decaying biological material that sinks to the sea bottom and makes its way into the crustal aquifer, producing carbon dioxide.
Researchers hope that this surprising find can help them better understand the overall global carbon cycle, which holds significance considering human-made carbon dioxide emissions that exacerbate to climate change.
Their discovery is described further in the journal Frontiers in Microbiology.
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