Deep in the Mariana Trench, the deepest part of the Earth’s oceans, scientists have discovered a unique oil-eating bacteria that can play a role in cleaning up man-made oil spills.
In a study published in the journal Microbiome, researchers from the University of East Anglia (UEA), and China and Russia, detail how they undertook the most comprehensive analysis of microbial populations in the trench, located in the Western Pacific Ocean and which reaches a depth of approximately 36,089 feet (11,000 meters).
To date, only a few expeditions have investigated the organisms inhabiting this ecosystem. One of them was organized and led by noted marine explorer and Academy Award-winning film director James Cameron, who built a specialized submersible to collect samples in the trench.
“We know more about Mars than the deepest part of the ocean,” Xiao-Hua Zhang of the Ocean University in China, who led the study, said in a statement.
Zhang and his team collected samples of the microbial population at the deepest part of the Mariana Trench, studied the samples that were brought back, and identified a new group of hydrocarbon degrading bacteria.
“Hydrocarbons are organic compounds that are made of only hydrogen and carbon atoms, and they are found in many places, including crude oil and natural gas,” said Dr. Jonathan Todd, from UEA’s School of Biological Sciences. “So these types of microorganisms essentially eat compounds similar to those in oil and then use it for fuel. Similar microorganisms play a role in degrading oil spills in natural disasters such as BP’s 2010 oil spill in the Gulf of Mexico.”
The team not only found that the hydrocarbon degrading bacteria was abundant at the bottom of the Mariana Trench, they found that the proportion of bacteria in the Trench is the highest on Earth.
The scientists isolated some of these microbes and demonstrated that they consume hydrocarbons in the laboratory under environmental conditions that simulate those in the Mariana Trench.
In order to understand the source of the hydrocarbons ‘feeding’ this bacteria, the team analyzed samples of sea water taken at the surface, and all the way down a column of water to the sediment at the bottom of the trench.
“We found that hydrocarbons exist as deep as 6,000 meters below the surface of the ocean and probably even deeper. A significant proportion of them probably derived from ocean surface pollution,” said Dr. Nikolai Pedentchouk, from UEA’s School of Environmental Sciences.
To the researchers’ surprise, they also identified biologically produced hydrocarbons in the ocean sediment at the bottom of the trench, which suggests that a unique microbial population is producing hydrocarbons in this environment.
“These hydrocarbons, similar to the compounds that constitute diesel fuel, have been found in algae at the ocean surface but never in microbes at these depths,” Pedentchouk said.
According to the study, these hydrocarbons may help microbes survive the crushing pressure at the bottom of the Mariana Trench, which is equal to 1,091 kilograms pressed against a fingernail.
Said Dr. David Lea-Smith, of UEA’s School of Biological Sciences: “They may also be acting as a food source for other microbes, which may also consume any pollutant hydrocarbons that happen to sink to the ocean floor. But more research is needed to fully understand this unique environment.”
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