Water droplets in the oil of asphalt were shown to be microhabitats for microbes and these microhabitats could be used to clean up oil spills. The microbial microhabitats were discovered in very small droplets of water that exist in the world’s largest asphalt lake, which is Pitch Lake in Trinidad and Tobago. The researchers also showed that the microbes were degrading the oil in the asphalt.
The droplets of water in the asphalt (which is like tar) were very small with a volume of only a few microliters, which is about one-twentieth the volume of a drop of water. Even though the composition of the asphalt includes very little water, the water droplets that were there had a mini ecosystem inside. The microbes in the water droplets were said to be metabolically active in that the microbes were able to carry out anaerobic (not needing oxygen) degradation of hydrocarbons at the oil-water transition zone. The microbial community degrades the oil into a variety of metabolites, according to the studies carried out by the scientists.
The low percentage of water content and the relatively large surface area of the droplets means there is a potential for oil biodegradation. The activity of this biodegradation can affect the quality of oil reservoirs. Oil companies are interested in reducing biodegradation in oil reservoirs, to prevent what is called “heavy oil,” and this discovery hints that they may want to try to prevent the development of the water droplets in oil, which would lessen the amount of biodegradation.
The study was carried out by scientists at institutions in Germany, The University of the West Indies in Trinidad and Tobago and Washington State University, and the report was published in the journal Science. DNA sequencing was used to analyze the microbial communities found in the water droplets.
A comparison of the chemical compositions from water samples of lake oil mixed with water, which acted as controls, showed they were distinctly different from the chemical compositions of the microdroplets. These results were said to indicate that the microorganisms in the microdroplets in the asphalt were actually eating and processing oil. The researchers thought that they would only find microbial communities at the bottom of the asphalt lake, because that is where groundwater could be found, and they considered the discovery of the microdroplets of water with microbial communities interspersed in the asphalt as unexpected.
In an interesting twist on the discovery, some have suggested that studying the microbial microhabitats may help to identify how life could exist on other planets. Astrobiologists have said that the asphalt lakes on Earth may be similar to conditions below the hydrocarbon lakes on Titan, which is Saturn’s moon. This similarity suggests that life similar to bacteria on Earth could possibly exist in these hydrocarbon lakes on Titan and other planets. Living in tiny water droplets may be a strategy for life to exist in inhospitable conditions on other planets.
Many more research studies are necessary before practical applications in oil spill clean-up will be possible. It is very hopeful, however, that use of these microbial microhabitats could be applied to clean up dangerous oil spills that create so much damage to the environment and animal life.
By Margaret Lutze