The contamination cleanup strategy called bioremediation—using naturally occurring microbes to clean up our messes—is gaining steam, as scientists devise new ways to use bugs against mercury, oil spills, radioactive waste and more.
Microbes are nature’s ultimate garbage disposal, devouring the dead, decomposing and inert material that litters Earth’s surface. They’re so good at it, in fact, that humans have taken an increasing interest in coercing them to clean up our environmental messes.
The concept is called bioremediation, and it involves using organisms that either naturally love to eat contaminants or have been genetically altered to give them the taste for toxins. Scientists are designing or deploying microbes to purge sites of contaminants such as PCBs, oil, radioactive waste, gasoline and mercury, and new bioremediation research appears regularly.
Pollution-eating bacteria have gotten the most press at large oil spills, such as the Exxon Valdez and, more recently, the Deepwater Horizon disaster. Scientific entrepreneurs poured out of the woodwork, eager to contribute their oil-eating superbugs to the cleanup effort. But, in reality, the microbes that were already there had a head start. “Bioaugmentation in the open environment really isn’t effective,” says Kenneth Lee, a researcher with Canada’s Department of Fisheries and Oceans who has extensive experience researching bioremediation of oils spills. Bioaugmentation is a type of bioremediation that involves adding organisms directly to the open environment. But microbes that aren’t adapted to the environment die quickly, simply providing more nutrients for the indigenous bacteria to feed on. “That’s an extremely expensive way to make fertilizer,” says Terry Hazen, the head of the Center for Environmental Biotechnology at UC Berkeley.
With a bacterial-based oil spill cleanup, there is an additional step beyond adding nutrients that give microorganisms a boost. During the Deepwater Horizon cleanup, for instance, responders dumped loads of chemical dispersants
to try to break up the oil in the Gulf of Mexico. One benefit of such an action is that it breaks the oil down into pieces small enough for the bacteria to eat. “When bacteria attack oil they can only attack from the water-oil interface” Lee explains. When a spill breaks up, its surface area gets larger and the microbes have an easier time feasting upon it.