Soil bacteria thrive on toxic chemicals

Shewanella oneidensis growing on the surface of the iron oxide mineral hematite. Image from Pacific Northwest National Laboratory

Researchers are Ohio State University are studying the ability of common soil bacteria to convert toxic metals into a non-toxic form. Soil bacteria are usually buried in underground or submerged in water so have developed an alternative way to obtain the oxygen it needs to survive. The Shewanella oneidensis bacterium feed on a variety of the metals normally found within the soil to obtain the oxygen they need to survive. More importantly, these bacteria are also able to feed upon toxic metals found in contaminated areas. In the process, the bacteria are able to change soluble toxic metals that can leak into the water supply into a more stable, insoluble form.

The process of bioremediation is a technique where organisms such as bacteria feed upon contaminants, pollutants or waste materials into less harmful substances. The United States Geological Survey (USGS) has used naturally occurring bacteria to clean up petroleum such as kerosene or gasoline spills, creosote contaminants from wood preservation, agricultural chemicals such as herbicides, and raw sewage. The most famous example of bioremediation was the treatment of the Exxon Valdez crude oil spill in Prince William Sound Alaska.

The Department of Energy supported the current study. According to Brian Lower, assistant professor in the School of Environment and Natural Resources at Ohio State, “we can use the bacteria to remediate nasty compounds such as uranium, technetium, and chromium." These hazardous and toxic materials were produced during nuclear weapon production in the 1960s and 1970s. 

With better understanding of how the bacteria is able to modify the toxic metals it may be possible to use Shewanella to more efficiently remediate these potentially deadly wastes.

Why does it matter?

Organized recycling of materials is a relatively new concept to society.  However, the planet has been practicing recycling for billions of years.  In the normal process of life and death, materials are used to form structures during life and returned to the environment when the body decomposes after death.  The term biodegradable means that a material can be used as a food source for a living organism and in essence recycled.  With the creation of man-made synthetic chemicals, more materials are non-biodegradable.  These materials will gradually build up as pollutants in the environment will only break down slowly over a long period of time.  The discovery of bacteria such as Shewanella increase the ability to use potentially harmful materials as a food source and promote the normal process of recycling. 

Adapted from materials provided by University of Pennsylvania, via EurekAlert!, a service of AAAS.

For more info: Read the United States Environmental Protection Agency publication "A Citizen's Guide to Bioremediation"