Researchers gathered samples of microbial communities in layers of sand containing oil from the Deepwater Horizon spill. They found that the perturbation led to growth of a succession of microbes that broke down portions of the oil over time. Photo: Markus Huettel.
When oil from the Deepwater Horizon spill began washing ashore on Pensacola Municipal Beach in June 2010, populations of sensitive microorganisms, including those that capture sunlight or fix nitrogen from the air, began to decline. At the same time, organisms able to digest light components of the oil began to multiply, starting the process of converting the pollutant to carbon dioxide and biomass.
Once the lightest fractions of the oil had been consumed, the organisms that had been digesting those compounds declined, replaced by others able to chew up the remaining heavier materials. A year after the spill, the oil had mostly disappeared and microbial populations buried in the beach sands looked much like they had before the spill, though there were as-yet unexplained differences.
That’s the progression observed by scientists who studied the oil’s impact on the complex microbial communities — which contain hundreds of different species of single-celled organisms — on this one Gulf Coast beach. Using advanced genomic identification techniques, they saw a succession of organisms and identified population changes in specific organisms that marked the progress of the bioremediation. They also identified the specific genes contained in the oil-eating microbes.
“We observed the succession of organisms whose populations rose and fell as the degradation of the oil proceeded,” said Kostas Konstantinidis, an associate professor in the Georgia Tech School of Civil and Environmental Engineering. “We also identified the indicator organisms that show the ecosystem’s response at different stages in the process. Knowing these indicators could help those who must manage these spills in the future.”
The research, reported in The ISME Journal and supported by the National Science Foundation and the BP/Gulf of Mexico Research Initiative to the Deep-C Consortium, provides a better understanding of the microbial succession process that follows such environmental perturbations. The project also involved researchers from Florida State University. — JOHN TOON