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Prof. Friedrich Widdel

Direktor Abteilung Mikrobiologie
Max Planck Institute for Marine Microbiology, Bremen
Phone:+49 421 2028-702Fax:+49 421 2028-790

Ecology . Microbiology

Growing bacteria to combat oil spills?

Each time a large oil spill occurs, experts argue about how such disasters could be avoided in the future and the best ways to tackle the pollution. Time and again, the use of laboratory-grown bacteria is brought up – bacteria that supposedly could devour the oil with lightning speed – much more quickly and efficiently than naturally occurring microbes. From a microbiological perspective, however, such a huge deployment of bacteria is hardly feasible. Even if the bacteria should survive the abrupt transition from the laboratory environment to the ocean and would begin to feed on the oil, the degradation would soon slow down because the microorganisms also consume essential minerals from the surrounding seawater.

Only if oil spills are dispersed into tiny droplets, can bacteria degrade them effectively. But even then, a deficiency of oxygen and nutrients slows down the degradation speed. Furthermore, anaerobes thrive too slowly to clean up vast areas of pollution. Zoom Image
Only if oil spills are dispersed into tiny droplets, can bacteria degrade them effectively. But even then, a deficiency of oxygen and nutrients slows down the degradation speed. Furthermore, anaerobes thrive too slowly to clean up vast areas of pollution. [less]

Another problem is that the aerobic bacteria, which break down oil very efficiently, require a lot of oxygen to do so. This leads to a lack of oxygen, often within a millimeter of the surface of an oil layer on the shore – and this in turn hampers the degradation process. The anaerobic bacteria, on the other hand, work too slowly to be able to eliminate the oil before it becomes a dense, tarry mass.

To make matters worse, the bacteria are active only in the boundary layer between water and oil. Hardly any degradation takes place in the middle of the oil layer, so as the oil slicks become thicker, the degradation rate decreases. 

 

GLOSSARY

Anaerobes
Organisms whose metabolism works without oxygen, in contrast to that of aerobes. To many of them, oxygen is even toxic.

Gas chromatograph
A device that separates the substances of a mixture. Using a carrier gas, the mixture is sent through a thin, 10- to 50- meter-long column that is wound into a coil. The capillary column is coated with a material to which substances will be absorbed for varying periods of time, depending on their polarity and their vapor pressure. The materials will thus exit the column after varying lengths of time.

Alkanes
Compounds consisting of carbon and hydrogen that contain no double bonds. The carbon atoms thus form a chain that may be branched or joined up in a ring. A hydrogen atom is bonded to any free bonding point. They are obtained primarily from crude oil.

 
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