Ocean
Industrial ship in oil spill on sea, Gulf of Mexico, Mississippi. Nic Kirschner/Getty
  • The deepest part of our planet is the Mariana Trench, which stretches some 7km down into the depths of the Pacific Ocean.
  • This dark and deep world is home to many denizens that are a far cry from the cuddly marine life found closer to the surface. One such resident is a new group of bacteria that degrade hydrocarbons - molecules that are found in everyday crude oil and gas.
  • A new study reveals that these hydrocarbon-eating bacteria are more abundant in the Challenger Deep (the deepest part of the Mariana Trench) than anywhere else on the planet.
  • These oil-eating microbes could help clean-up the next major man-made oil spill on the ocean surface.

Scientists know more about the furthest reaches of deep space than they do about the deepest parts of our planet's oceans.

In the heart of the Pacific Ocean, some 201km north of Guam under nearly 11,000 metres of ocean, lies the Challenger Deep.

The deepest part of the infamous Mariana Trench - a 69 km-wide crescent canyon that cuts its way through 2,414 km of ocean at the edge of two tectonic plates - the Challenger Deep is home to a unique ecosystem of creatures and microorganisms. (It's also the final resting place of thousands of man-made microplastic pollutants.)

According to a new study published in the journal Microbiome, a group of bacteria trawled from the depths of the Challenger Deep can not only survive its extreme conditions, but also chomp on hydrocarbon molecules found in everyday crude oil and natural gas.

Oil-eating bacteria like these are also found on the ocean's surface, and helped degrade much of the oily refuse that spilled into the Gulf of Mexico after the 2010 Deepwater Horizon disaster. The scientists think these microbial deep ocean oil-eaters can also be used to clean up surface oil spills.

Challenger Deep is "inhospitable to nearly every organism on the planet. Cold and completely dark. What is most extreme is the intense water pressure which would crush most organisms in a fraction of a second," Jonathan Todd, a biologist from University of East Anglia in the UK and a co-author on the study, told Business Insider.

"How the microorganisms survive this environment is still a mystery and this is another of our key future research questions," he added.

Collecting samples from 11 km below the surface

Collecting samples from the crushing depths of the Challenger Deep is no easy feat. To date, only a few expeditions have investigated the denizens that make their homes 11 km below the ocean's surface (sorry Jason Statham fans, no live Megaladons have been discovered as of yet).

In order to get samples, researchers dropped bottles and corers into the ocean and sampled water and sediment at different depths in the Mariana Trench.

"Just think about the size and weight of the cable required to fish at depths of more than 10 kilometers," Todd said.

After they examined their samples, the team identified a new group of oil-eating bacteria, and determined that the proportion of hydrocarbon-munching bacteria in the Mariana Trench is higher than anywhere else on Earth. (These bacteria are found in nearly every environment on the planet.)

Todd and his team aren't sure yet why that's the case. "It may be that there is a higher proportion of hydrocarbons compared to other nutrient sources in the Mariana Trench, which supports this particularly large population," Todd said. These hydrocarbons could accumulate within the trench due to its unique topography, he added.

The study authors think the hydrocarbon nutrients could be the secret to these bacteria's success in the Challenger Deep's extreme environment, where pressures reach some 6,000 kg per square inch - more than 1,000 times the pressure at sea level.

These oil-chomping microbes could combat man-made spills

Hydrocarbon-eating organisms have already been used to help degrade man-made oil spills.

In 2010, the Deepwater Horizon spill off the coast of Louisiana poured some 200 million gallons of oil into the Gulf of Mexico. An area the size of Rhode Island was closed off from fishing, and local economies tanked.

Several species of hydrocarbon-eating bacteria, like Alcanivorax borkumensis, feasted on the spilled oil, assisting with the disaster clean-up efforts.

Alcanivorax was one of the types of bacteria that Todd and his group found in the Challenger Deep.

Todd thinks it's possible the bacteria pulled from the Mariana Trench could similarly assist in oil spill clean-ups. When tested in the lab, these microorganisms from the ocean depths "very efficiently consumed" the types of hydrocarbons that surface bacteria like Alcanivorax borkumensis degraded after the 2010 Gulf oil spill.

While Todd said further work is required "to test the potential of these novel bacteria," the team believes that the hydrocarbon-eating bacteria from the bottom of the ocean could consume any oil found on the surface.

For more, go to Business Insider South Africa.

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