Oil-eating microbe communities a mile deep in the Gulf

Jul 09, 2013 by Steven Powell
Oil-eating microbe communities a mile deep in the Gulf
The oil slick in the Gulf of Mexico, as seen from satellite on May 24, 2010.

The Deepwater Horizon explosion on April 20, 2010, caused the largest marine oil spill in history, with several million barrels of crude oil released into the Gulf of Mexico over the course of three months. Soon after the spill began, a massive oil slick was visible from orbiting satellites, yet once the underwater gusher was sealed, obvious traces of the crude oil disappeared much sooner than nearly all observers predicted.

Some of the oil evaporated; some was skimmed off. Microbes "ate" much of the oil as well – the ocean hosts a variety of that feed on the hydrocarbons that make up crude oil, digest them, and eventually release their remnants as carbon dioxide. These aerobic microbes use oxygen dissolved in the sea to oxidize hydrocarbons to carbon dioxide.

In the deep- of the , though, oxygen is a rarer commodity, so anaerobic microbes might have to shoulder the lion's share of any crude . And the is where some of the certainly settled – just how much, though, and its fate, is the subject of differing viewpoints in the scientific community.

Pamela Morris of the University of South Carolina helped lead a team of scientists that recently released a study shedding light on those questions. The team's metagenomic analysis of the deep-sea subsurface sediments was published in Frontiers of Microbiology.

In mid-September 2010, two months after the gusher was sealed, a Lawrence Berkeley National Laboratory team led by Terry Hazen began collecting deep-sea in the area surrounding the epicenter of the spill. The samples were shipped to Morris' laboratory at USC's Belle W. Baruch Institute in Georgetown, S.C., where she oversaw an analysis of the community genome in the deep-sea subsurface.

Using a pyrosequencing platform, the team quantified genes from three sample sites – two were less than 3 km from the Deepwater Horizon rig, and one was 128 km from it – and classified the microbes phylogenetically.

Owing to the extreme depth (1500 meters) of the waters in the area, the data were a substantial addition to the dearth of existing data points. "In the Gulf of Mexico, the only metagenomes that were available to compare to were the Brazos-Trinity and Peru Margin," said Morris, referring to samples obtained from off the coast of Texas and Peru, respectively.

In the sample areas closest to the spill site, the Deltaproteobacteria class was more abundant within the microbial community. Moreover, an early analysis of probable anaerobic hydrocarbon metabolites (alkylsuccinates) lent credence to the conclusion that anaerobic bacterial species in this class were responding to the presence of hydrocarbons on the seafloor.

"We weren't able to analyze as many samples as we would have liked," Morris said. "But in these deep-sea subsurface sediments, it does look like the microbial communities are becoming enriched in species that are capable of anaerobic oil degradation near the spill area. The metagenomic analysis we did suggests that there's a shift toward organisms with the capability to anaerobically degrade oil, and the preliminary metabolomic data validated that. We hope to explore this further."

Given the amount of oil that was released, Morris thinks developing a better understanding of the microbe community on the sea floor is crucial.

"Some of the oil most likely settled in some of these deep regions in the Gulf of Mexico. There's no idea of how much of it did – there are differing views in the scientific community," Morris said. "We need to get a better feel for what's going on in these deep-sea sediments that are contaminated."

Explore further: Dead floppy drive: Kenya recycles global e-waste

More information: dx.doi.org/10.3389/fmicb.2013.00050

add to favorites email to friend print save as pdf

Related Stories

Source of persistent Gulf sheen remains a mystery

Dec 18, 2012

Officials say underwater inspections at the site of BP's Deepwater Horizon rig disaster have failed to identify the source of a persistent sheen on the surface of the Gulf of Mexico.

Recommended for you

Dead floppy drive: Kenya recycles global e-waste

18 hours ago

In an industrial area outside Kenya's capital city, workers in hard hats and white masks take shiny new power drills to computer parts. This assembly line is not assembling, though. It is dismantling some ...

New paper calls for more carbon capture and storage research

22 hours ago

Federal efforts to reduce greenhouse gas emissions must involve increased investment in research and development of carbon capture and storage technologies, according to a new paper published by the University of Wyoming's ...

Coal gas boom in China holds climate change risks

Aug 22, 2014

Deep in the hilly grasslands of remote Inner Mongolia, twin smoke stacks rise more than 200 feet into the sky, their steam and sulfur billowing over herds of sheep and cattle. Both day and night, the rumble ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (4) Jul 09, 2013
I wish that you fucking Americans would use LITRES in your measurements....

Idiot scientific publication... "Oooooo barrels, hog's heads and furlongs"
2 / 5 (4) Jul 15, 2013
I wish that you fucking Americans would use LITRES in your measurements....

Idiot scientific publication... "Oooooo barrels, hog's heads and furlongs"

We haven't entirely managed to get them to stop using cubits or trying to legislate that pii equals exactly 3.