How an army of oil-eating bacteria can clean up the Gulf

Some bacteria have serious oil-eating capabilities, say a team of researchers in their paper published Monday in the journal Nature Microbiology.

"This gives us an idea of who breaks down the oil and how they do it," author Nina Dombrowski, a postdoctoral researcher under co-author Brett Baker's lab at The University of Texas Marine Science Institute, tells The Christian Science Monitor. The team of researchers from UT, the University of North Carolina, and Heriot-Watt University analyzed bacterial species' relationships with oil in the context of BP's 2010 Deepwater Horizon spill in the Gulf of Mexico. "We are already naturally employing [the bacteria], nature is already doing it.... They can integrate it into their natural diet. Oil is a nutrient for them." 

The chemical makeup of oil is "extremely complicated," say the authors. Of the two main components, alkanes and aromatic hydrocarbons, the latter is "much trickier to get rid of," says Dr. Dombrowski. 

But through gene sequencing of commonly known oil-eating bacteria such as Alcanivorax and Neptuniibacter, as well as other less-studied bacteria, the UT researchers found that many species were indeed capable of breaking down the tricky hydrocarbons. 

"The presence of major genes for motility and for use of scarce nutrients suggests that the enriched organisms are well adapted ... for physiological responses to nutrient-limiting conditions that characterize oil-induced bacterial blooms," the authors explain in their paper. "Alternatively, these genes might be of general importance for survival and growth in the Gulf of Mexico." 

Since the 1969 oil well spill in Santa Barbara, there have been at least 44 oil spills of more than 10,000 barrels, or 420,000 gallons, in US waters, says the US National Oceanic and Atmospheric Administration. And NOAA says this is an underestimate: Their assessment does not take into account spills outside of NOAA involvement, terrestrial and underground spills, and spill volume-adjustment due to fire, sinking, and hurricanes.

By comparison, the Deepwater Horizon spill – often called the worst environmental disaster in US history – spilled 4.2 million barrels of oil into the Gulf.

But can microscopic bacteria really make a difference against millions of barrels of oil? 

"I would believe so," says Dombrowski. "A large proportion of the spilled oil was unaccounted for [at Deepwater Horizon], we didn't know where it went. So it's possible that these bacteria were able to get rid of a portion of this oil."

And to ensure bacterial species like Alcanivorax and Neptuniibacter continue to fight back against human pollution, we need to help them do their job says Dombrowski.

"We need to understand what our natural responses are doing to the bacteria community, we need to figure out how we can support these bacteria in doing their job better," explains Dombrowski. For example, after the Gulf spill, dispersants were added to the spilled oil in hopes of breaking down the concentrations of oil. "But by adding the dispersants, we might change the natural communities.... Everything you add after the spill could alter the communitive structure of bacteria. It's likely that the bacteria work together to break down oil, so if you alter this structure it won't be helpful."

Earlier this month, two biologists from Indiana University found that 1 trillion microbial species likely live on Earth, and humans only know about 0.001 percent of them. Even more reason, say the authors, to promote understanding and conservation in the world of microbiology. 

This recent catalogue of 1 trillion microorganisms demonstrates "the sheer diversity of microorganisms that surround us, and how little we know about them," Simon Malcomber, lead program director for the National Science Foundation's Dimensions of Biodiversity, which funded the IU study, told the Monitor earlier this month. "This study emphasizes how we need to increase our efforts to document and describe this microbial diversity and then start to understand the myriad roles these organisms likely play in global ecosystems." 

"It's equivalent to a concert," says Dombrowski in a press release. "All the musicians have to work together to make a piece of beautiful music. After the spill, all bacteria must work together to efficiently degrade oil."