Bacteria living in the Gulf of Mexico beaches were able to 'eat up' the contamination from the Deep Water Horizon oil spill by supplementing their diet with nitrogen, delegates at the Goldschmidt conference will be told today, Friday 30th August.
Professor Joel Kostka will tell geochemists gathered in Florence for the conference that detailed genetic analysis showed some of the bacteria thrived on a diet of oil because they were able to fix nitrogen from the air. The research -- the first to use next generation sequencing technologies to dig into the detail of how the native beach microbes are metabolising the oil over time -- could open the door to much more sophisticated clean up techniques.
"Oil is a natural product, made of decayed plants and animals, and so is similar to the normal food sources for these bacteria." explains Professor Kostka, a microbiologist from Georgia Institute of Technology in Atlanta. "But because oil is low in nutrients such as nitrogen, this can limit how fast the bacteria grow and how quickly they are able to break down the oil. Our analysis showed that some bacteria are able to solve this problem themselves -- by getting their own nitrogen from the air."
Professor Kostka worked with Professor Markus Huettel, a biogeochemist from Florida State University, to take more than 500 samples over two years from Pensacola beach in the Gulf of Mexico, starting when the Deep Water Horizon oil slick first came ashore in June 2010. By analysing every gene of every bacteria in the sample, they were able to see which bacteria were present and how they responded as the conditions on the beach changed.
The researchers looked at the prevalence of genes which encode for different types of activity -- such as nitrogen fixing or phosphorus uptake -- to identify exactly how the bacteria were degrading the oil.
"By understanding how the oil is degraded by microbes, which microbes do the work, and the impact of the surrounding environmental conditions, we can develop ways to intervene to support the natural clean-up process," says Professor Kostka. "However, we need to do this in a very measured and targeted way, to avoid long-term, unintended damage to the ecosystem. For example, in the past, nitrogen fertiliser has been sprayed onto contaminated beaches to speed up the work of the bacteria. Our analysis shows that, where bacteria can get this nitrogen naturally, such drastic intervention may not be necessary."
The genetic analysis carried out by Professor Kostka and his colleague Konstantinos Konstantinidis at Georgia Tech can show exactly how the oil-degrading bacteria are working at each part of an affected coastline, making it possible to identify which beaches are most effective at self-cleaning and target mitigation efforts -- such as offshore booms -- at the most vulnerable areas.
But not all the bacteria thrived on a diet of oil. Professor Kostka's research showed that some bacteria which play an important role in the ecosystem of the beaches experienced a sharp decline following the contamination in June 2010.
"There's a tendency to focus on the short-term, visible effects of an oil spill on the beach and assume that once the beach looks 'clean' then all is back to normal," he says. "Our analysis shows some of the invisible impact in the loss of these important microbes. We need to be aware of the long-term chronic damage both a spill -- and in some cases our attempts to deal with it -- can cause."
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Notes to editors:
1. The Goldschmidt Conference is jointly sponsored by the European Association of Geochemistry and the Geochemical Society. The annual, five-day event brings together around 4000 of the world's leading geochemists, covering topics as diverse as planetary formation, volcanoes, tectonics, climate change and oceans.
Goldschmidt2013 -- the 23rd Goldschmidt conference -- is being held in Florence between 25-30 August. It is managed this year by the European Association of Geochemistry (EAG). http://goldschmidt.
2. Founded in 1985 to promote geochemical research, the European Association of Geochemistry (EAG) has now grown to a membership of over 3000. It is a not-for-profit organisation which provides a forum for the presentation and exchange of ideas between geochemists across Europe. EAG produces two journals -- Chemical Geology and Geochemical Perspective. http://www.
3. The Geochemical Society (GS) was founded in 1955 with the aim of encouraging the application of chemistry to the solution of geological and cosmological problems. It now has over 3000 members and sponsors the journal Geochimica et Cosmochimica Acta. http://www.
4. Joel Kostka is a Professor in the Schools of Biology & Earth and Atmospheric Sciences at Georgia Institute of Technology and is internationally recognized for his research program in the areas of environmental microbiology and biogeochemistry. From 2008 to 2011, he served as Associate Director for Bioenergy Development in the Institute for Energy Systems, Economics, and Sustainability at Florida State University. Professor Kostka sits on the steering committee and as a coPI of the consortium "Deep-C: Deepsea to Coast Connectivity in the Eastern Gulf of Mexico" funded at $20 million by the Gulf of Mexico Research Initiative to study the environmental consequences of petroleum hydrocarbon release in the deep Gulf on living marine resources and ecosystem health.