Norwegian scientists say bacteria to clean up after oil spills

March 24, 2014

Researchers in Trondheim have achieved surprising results by exploiting nature's own ability to clean up after oil spills, SINTEF’s press office said on March 7.

"We know that oil spills happen – and that they will happen again", says Roman Netzer, a researcher and biologist at SINTEF. "We also know that this can have a major negative impact on the natural environment. This is why we've been studying a series of chemical and biological analytical techniques to assess the levels of seriousness of oil spills. We also wanted to find out whether so-called bioremediation represents an effective approach to cleaning up after such accidents", he explains.

When we clean up after an oil spill of a given size, such as along our shorelines, we start by applying mechanical methods using spades and brooms, combined with chemicals. However, we shouldn't deceive ourselves, even when the worst of the spill has been cleared away. The surface usually conceals oil buried deeper in the sediment.

"It is here that biological, or bioremediation, methods, come into their own", says Netzer. "This approach can make cleaning up operations even more thorough, and cost-effective. We wanted to find out what works – and how. And not least to gather data that can be used to support decision-making processes in situations where nature needs that little extra help" he explains.

So the researchers set up a number of experiments in the marine laboratory. Their aim was to look into how the microscopic residents of the oceans, such as bacteria and other microbes, can assist us in cleaning up pollutants, and whether they are capable of restoring the natural balance afterwards. And not least, to determine the limiting factors involved in this process. It was only after they had failed to achieve any significant response from their initial experiments, causing them to change the experimental parameters, that their sensational results emerged.

Sixteen tanks were filled with sediments, together with naturally-occurring bacterial flora, oil and seawater. The researchers also simulated the action of the tides by replacing the seawater and thus ensuring that there was an adequate supply of oxygen and nutrients. What then happened in the tanks was carefully recorded. But after a month of observations, only minor amounts of contaminants had been removed.

"However, we noted that the biological approaches, which analyse the concentrations of bacteria, their DNA, and oxygen consumption, were very sensitive and provided us with a great deal of information. Chemical approaches have to be very advanced in order to achieve the same detection thresholds" says Netzer.

"Even the results of the bacterial experiments were obviously disappointing", he explains. "But the biological results indicated that we were on the right track, and this gave us the idea to give nature a helping hand. We already knew that the bacteria would reproduce – and thus be more effective in their work – if they were provided with additional nutrients. In nature, bacteria flourish best in the presence of high concentrations of phosphates and nitrogen", says