Mystery Solved: Oil-Munching Bacteria Helped Clean Up the Deepwater Horizon Oil Spill

The Deepwater Horizon oil spill that began on April 20, 2010, was the largest maritime oil spill in history. Killing 11 people and discharging 4.1 million barrels of oil and natural gas into the Gulf of Mexico, the event was an unparalleled personal, environmental, and business disaster. It was also the first major oil spill to take place in the deep ocean.

As commercial and federal agencies struggled to stem the spill, marine life died or was born defective, and die-offs and environmental damage continued long after the undersea well was capped. Reports suggest the well continues to leak toxic contaminants. The blame was placed on British Petroleum, its rig operator and the contractor, Halliburton.

One of the world's most endangered turtles, this Kemp's Ridley Turtle was captured for cleaning and safe release

As a result of the explosion and flow of oil, about 40% of the crude, along with about 1.8 million gallons of chemical dispersant released into water, formed an ocean-going plume, nearly 100 miles long that slicked the surface — and the depths — of the ocean.

Considered an "important phenomena," the plume contained soluble and insoluble droplets of oil and chemicals that remained within the column of the plume and were degraded by ocean-dwelling microbial communities. At the time, obtaining samples below the slick over such a large area was difficult and dangerous, but some researchers found microbial communities within the plume were changing over time.

Four years later, a research team from the Lawrence Berkeley National Laboratory traveled to sample the still-polluted water. The researchers collected water to create a simulation of what occurred when oil, water, chemicals, and bacteria mix. The team was interested in naturally occurring bacteria in the water that helped to degrade the oil and the plume.

Researcher Gary Anderson, from Berkeley, explained in a press release: "We simulated the conditions of the Gulf of Mexico oil spill in the lab and were able to understand the mechanisms for oil degradation from all of the principal oil-degrading bacteria that were observed in the original oil spill."

The results of their study are published in the journal Proceedings of the National Academy of Sciences.

The slick of red and brown emulsion floating east of Louisiana

The study authors were looking for an as-yet undiscovered microbe believed to carry out a significant role early in the oil release. By carefully recreating conditions of the plume, with water samples from the site and analyzing the microbial actors, the team discovered a new microbe. It is tentatively named Bermanella macondoprimitus because of its similarity to already identified deep-sea microbes also present within the seawater cultures produced in the lab.

So now that we've discovered an oil-munching microbe — what is the big deal? By combining knowledge of the newly discovered organism along with earlier work on microbes that degrade hydrocarbons, Anderson says scientists can now identify specific microbes that could naturally degrade oil spills in other regions of the world. Their work also offers a process for estimating how long it would take for the bacteria to consume portions of a resulting plume.

To put it another way, the team was able to observe the successive generations of microbes that grew, died-back, and were replaced by other microbes. This is the same sort of process that occurs when bacteria colonize your coffee maker, or a bathtub that has not been cleaned in awhile. But in this case, science now has some idea of how to predict what microbes would take charge during a deep-sea oil well blowout, and how long they might take to degrade oil and chemicals released in the spill.

One of the tar balls formed from the oil spill. This one was found on Dauphin Island, Alabama.

The Conditions Were Right

Scientists believe the particular conditions in the Gulf of Mexico may have created a hospitable environment for hydrocarbon-eating microbes, even before the spill. Anderson said: "The Gulf of Mexico is home to one of the largest concentrations of underwater hydrocarbon seeps, and it has been speculated that this helped in the selection of oil-degrading microbes that were observed in the underwater plumes."

Scientists are still unsure about exactly how much oil pollution was handled by the microbes, and whether the chemical dispersants used to contain the oil helped, or hurt, the ongoing recovery of the natural environment. One limitation of the study, and all studies to date, is the inability to model or understand the impact of the enormous natural gas release that accompanied the explosion.

While everyone hopes a catastrophe of this nature does not occur again, it is probably only a matter of time before another avoidable accident fouls the waters, the skies, or the earth. When that happens, it just may be the very smallest organisms on the planet — microbes — to the rescue.

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Cover image via US Coast Guard