April 12 (UPI) -- Scientists have discovered oil-eating bacteria in the planet's deepest oceanic trench, the Mariana Trench.
An international team of researchers, including scientists from Britain, China and Russia, used a submersible to collect microbial samples from the trench, which bottoms out at 6.8 miles below sea level. For reference, the peak of Mount Everest is 5.5 miles above sea level.
Only a few expeditions to the Mariana Trench have been made, and the latest is one of the first to focus on the trench's microbial communities.
"We know more about Mars than the deepest part of the ocean," Xiao-Hua Zhang, a research professor at the Ocean University in China, said in a news release.
When researchers analyzed the microbial samples collected during the expedition, they found a new group of hydrocarbon degrading bacteria. They published the results of the study Friday in the journal Microbiome.
Hydrocarbons are organic compound made up of only hydrogen and carbon atoms. They're found in crude oil and natural gas, among other places.
"These types of microorganisms essentially eat compounds similar to those in oil and then use it for fuel," said Jonathan Toddy, researcher at the University of East Anglia. "Similar microorganisms play a role in degrading oil spills in natural disasters such as BP's 2010 oil spill in the Gulf of Mexico."
Researchers were surprised by the abundance of the oil-eating bacteria in the trench. Nowhere else on Earth are oil-eating bacteria so proportionally dominant.
To better understand where the microbes are getting their sustenance, scientists collected water samples the entire length of the water column, from sea surface to the sediments at the bottom of the Mariana Trench.
Scientists found the oil-eating microbes as deep as 4 miles beneath the ocean surface, and researchers suspect the microbes live at even greater depths.
The bacteria are likely deriving a significant portion of their food from pollution that sinks from the ocean surface. But scientists also found evidence that some of the hydrocarbons are sourced from below.
"To our surprise, we also identified biologically produced hydrocarbons in the ocean sediment at the bottom of the trench," said UEA researcher Nikolai Pedentchouk. "This suggests that a unique microbial population is producing hydrocarbons in this environment."
In addition to providing sustenance, researchers suspect the hydrocarbons help microbes survive the crushing pressures of extreme ocean depths.