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5/9/2016  Bacteria more effective on oil spills without dispersants, study finds


EDINBURGH, UK – Heriot-Watt University claims to have cracked the genetic code of the marine bacteria that helped “eat” the oil spilled from the Deepwater Horizon.
Dr. Tony Gutierrez, Associate Professor of Microbiology at the university, was in the US at the time of the spill and shortly after was able to perform experiments with samples from the oil-contaminated waters containing species of bacteria that fed on the oil.
Analysis showed that certain bacteria had thrived on the escaped oil, devouring it as a preferred food source.
In a paper published in Nature Microbiology, Dr. Gutierrez and his colleagues from the University of Texas and University of North Carolina at Chapel Hill reveal the genetic pathways these bacteria use to consume the oil; the conditions they thrive in; the type of oil hydrocarbons they can eat; and how they “co-operate” during an oil spill.
 “Understanding which bacteria are important to breaking down oil could help lead to the design of emergency response plans that are more effective and environmentally friendly for combating a major spill,” Dr. Gutierrez said. “We knew that certain bacteria will respond to and thrive during an oil spill and helped break down oil, but we didn’t know how this was coordinated.
“By reconstructing the genomes of these bacteria, we’ve discovered the pathways they use to breakdown the different types of hydrocarbon chemicals in oil, including some of the highly toxic ones, and the way the bacteria work as a community to degrade the oil.
“Different bacteria have different appetites for different hydrocarbons, but they can work beautifully in concert together to clean up polluted water.”
The findings also reveal an ability of these bacteria to move toward oil droplets and use scarce nutrients, suggesting that these microbes are effectively sentinels in the ocean, adapted to respond quickly to the influx of oil in the event of a spill.
The bacteria that worked best at different depths in the Gulf during the Deepwater Horizon spill were Oceanospirillales, which degraded alkanes in the deepwater oil plume; and Rhodospiralles and Cycloclasticus, responsible for degrading polycyclic aromatic hydrocarbons, recognized as among the most toxic of chemicals.
Dr. Gutierrez said: “Following an oil spill, dispersants are commonly used to break up the oil into very small droplets, making it easier for the bacteria to break it down.
“Our findings show that someof the bacteria that responded to the spill in the Gulf are also able to degrade dispersants, potentially rendering them ineffective after they have done their job…
“The hope is that our findings will allow us to exploit their oil-degrading potential on a wider scale, such as through more effective bioremediation strategies.”
Dr. Gutierrez is currently studying the capabilities of oil-degrading bacteria in UK waters where future oil spills might occur, with a view to designing effective bioremediation solutions, including evaluating the effectiveness of using chemical dispersants.