Cleaning Up: Remediation of Environmental Contamination
Microbial communities are crucial participants in cleaning up an astounding variety of both natural and human-made hazardous substances; 
they transform potentially deadly chemicals into forms that are benign both to people and to the environment. Some microbes consume methane gas—a major greenhouse gas—which seeps from landfills and swamps. Other microbes degrade the waste in sewage water at water treatment facilities.
Case Highlight: Keeping Groundwater Drinkable
Just about every gas station in the United States has three or more underground storage tanks from which it dispenses gasoline. The sad truth about these tanks is that many of them are either currently leaking or will leak at some time in the future, releasing gasoline into the soil, where it has the potential to contaminate groundwater. 
Given the ubiquity and magnitude of the gasoline leaks—coupled with the fact that 50% of the U.S. population relies on groundwater as a source of drinking water—one must wonder how we are not all drinking water contaminated with gasoline!
The answer is that we are often protected by the vastly adaptable microbial community found in the soil. As gasoline is released into the ground, relatively dormant members of the soil microbial community are triggered to become active and degrade the harmful chemicals in gasoline. Because gasoline is composed of hundreds of chemicals, it takes a variety of microbes working together to degrade them all. For example, when some types of bacteria cause a depletion of oxygen in the groundwater near a gasoline spill, 
other types of bacteria that can use nitrate for energy begin biodegrading the gasoline. Bacteria that use iron, manganese, and sulfate follow. These community members work together in a pattern triggered by the movement of the leaking gasoline until the contaminants have been transformed into harmless carbon dioxide and water.
Communities of marine bacteria, similar to the soil microbes that degrade gasoline leaks on land, can help clean up oil spills in the Earth's oceans. While we know that microbial communities are immensely useful in degrading waste and hazardous spills, our understanding of the processes involved—and how to channel those processes to 
manage the fast-growing array of chemicals humans put into the environment—is as yet limited. Metagenomic analysis may help us identify the particular community members and functions needed to achieve the full chemical transformations that will keep our planet livable.
The information on this Web page was derived from the National Research Council report The New Science of Metagenomics: Revealing the Secrets of Our Microbial Planet (2007) and the 20-page educational booklet derived from that report, Understanding Our Microbial Planet: The New Science of Metagenomics.
PHOTO CREDIT: Image of oil spill courtesy NOAA HAZMAT.
Support for this web publication was provided by the Presidents' Circle Communication Initiative of the National Academies.
