During an oil spill, liquid petroleum is released into the environment and the black sticky substance covers everything it touches: soil, water and wildlife. Between 1970 and 2007, nearly 6,062,712 tons (5.5 million metric tons) of oil were spilled in incidents around the world [source: The International Tanker Owners Pollution Federation]. The costs associated with each cleanup are influenced by a combination of three factors: the location of the incident, the type of oil spilled and the amount of oil spilled. Cleanup response and strategy is also based on these factors. Standard response to oil spills includes cleanup equipment and techniques consisting of mechanical containment (such as booms, barriers and skimmers), chemical and biological methods (including dispersants to break up the oil), physical methods (such as pressure washing) and scare tactics to keep wildlife at a safe distance.
Using techniques such as dispersants or mechanical recovery to remove an offshore spill costs an average of $7,350 per metric ton of oil. Cleanup costs of shoreline spills jump to an average of $147,000 to $294,000 per metric ton because of the additional coastline damages [source: Etkin]. Because equipment needs to be brought to the scene of the incident, commonly flown in, remote spills can sometimes present logistical problems.
Currently, mechanical containment is the most popular method of recovery in the United States, but it's only able to clean about 10 to 15 percent of a spill [source: European Commission, Environmental DG]. Microbiologists are heralding an environmentally friendlier technique: bioremediation through biological remedial agents. Bioremediation treats pollutants (such as an oil spill or contaminated groundwater) with bacteria bioengineered to break down contaminants. Add to that bioluminescence and color-coding, and you get bacteria that not only eats oil but also helps alert us to the presence of oil spills and other environmental pollutants seeping from pipes or storage tanks into water or soil.
Bacterial Bioluminescent Biosensors
Bioluminescence is a visible light emitted from a living organism, such as the glow of a firefly or jellyfish. The bioengineered bacteria used as bioremedial treatment agents are single-celled organisms that don't glow naturally, but are modified by scientists to do so. The altered bacteria each carry a reporter protein and a sensor.
Let's start with the importance of the reporter protein. Bioluminescence is a chemical reaction caused by an enzyme-catalyzed process: The enzymes that produce light are called luciferin, and those that are the catalyst are called luciferase. The reporter is responsible for this enzymatic activity, which releases bioluminescence energy and gives the bacteria its color. You won't see this bacteria's blue-green glow in the ocean though; its reporter protein is visible under a microscope or with a special light recording device.
The sensor is how the bacteria is able to continually check for the presence of certain chemicals, determined by the scientists who bioengineer the organisms. It also allows the bacteria to detect the concentration and distribution of pollutants and whether or not they are spreading.
Bioremedial treatments are a relatively cheap and easy recovery method compared to traditional chemicals and equipment. In initial studies, bacteria has shown its ability to clean up oil spills more rapidly than traditional techniques and reduce damage to ecosystems in the process.
Environments rich in phosphorous and nitrogen (water-soluble fertilizers found in natural elements like soya bean lecithin and bird excrement) encourage the bacteria to thrive, eating toxic waste and leaving carbon dioxide and water as the only byproducts of their consumption. In such an environment, bioremedial treatments have been found to remove 87 percent of oil within 18 days [source: European Commission, Environmental DG]. When the food (in this case, hydrocarbons) runs out, the bioengineered bacteria die.
Although the bacteria are reported to be safe for release in the natural environment due to their inability to reproduce well in the open and their natural death cycle, government regulations often make it difficult to use them because they have been genetically altered. For now, the bacterial agents used to gobble up oil spills tend to be naturally occurring types with a taste for toxic waste.
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