Earth Science News  





. Bacterium Could Treat PCBs Without The Need For Dredging

Series of electron micrograph scans of Dehalococcoides
by Staff Writers
Troy, NY (SPX) Mar 12, 2007
Researchers at Rensselaer Polytechnic Institute have discovered a tiny bacterium that could one day transform the way we remove polychlorinated biphenyls (PCBs) from our environment. The organism could be the key to developing methods that help detoxify commercial PCB compounds on site - without the need for dredging.

The results will appear in the April 15 issue of Applied and Environmental Microbiology.

Commercial PCBs, which were banned from production in the United States in 1977, were once commonly used by industry. The compounds are mixtures of 70-90 different molecular forms that vary in the number and positions of chlorine atoms, making them difficult to degrade. To date, the most commonly used method to remove PCBs from the environment is to dredge and then deposit the sediments in a landfill.

In order to detoxify PCBs the strong bonds between the chlorine atoms and the biphenyl compounds that make up the PCB atomic structure need to be broken, a process known as dechlorination. More than two decades ago, scientists discovered that PCBs were slowly being dechlorinated by naturally occurring microbes, but despite years of research, the exact microbes responsible have remained elusive - until now.

"For the first time we have been able to cultivate in defined media naturally occurring bacteria that can extensively dechlorinate PCBs right at the site of the contamination," said Donna Bedard, professor of biology at Rensselaer and lead author of the paper. "This is a major step toward the development of cost-effective methods for on-site PCB remediation."

Bedard used sediments from the Housatonic River in Massachusetts - an area known to be contaminated with PCBs - to develop sediment-free cultures and to identify the bacteria that were breaking down the PCBs. Using molecular techniques, the research team determined that the microbes that are dechlorinating the PCBs belong to a group of bacteria known as Dehalococcoides (Dhc).

Dhc are "strict anaerobic" bacteria, which means they cannot survive in the presence of oxygen. They are frequently involved in natural remediation of chlorinated solvents such as trichloroethylene (TCE), but this is the first time it has been demonstrated that Dhc can dechlorinate complex commercial PCB mixtures.

After identifying the Dhc bacteria, Bedard and her team proved that the anaerobic bacteria thrive on the PCBs, much as humans thrive on oxygen. The microbes replace the chlorines on the PCBs with hydrogen, which fuels their growth and begins the PCB degradation process.

The discovery of the Dhc bacteria's unique abilities could one day alter the way we treat PCB contaminated water bodies, according to Bedard.

"Now that we have identified the PCB-dechlorinating bacteria and learned how to cultivate them in the laboratory, we can begin to understand the processes that they use to dechlorinate PCBs and tap their unique abilities to create new technologies that efficiently and safely remove commercial PCBs from our environment," she said.

The research was funded through a grant from the National Science Foundation. Bedard was assisted in her research by Kristi Ritalahti and Frank Loffler of the Georgia Institute of Technology.

Email This Article

Related Links
Rensselaer Polytechnic Institute
Our Polluted World and Cleaning It Up

Asian Pollution Linked To Stronger Pacific Storm System
Chicago (AFP) Mar 05, 2007
Increasing levels of environmental pollution in Asia are changing atmospheric conditions over the north Pacific and may explain stronger-than-usual thunderstorms over this part of the ocean during winter months, a study released Monday suggested. US climatologists say the dramatic increase in pollution from Asia over the past few decades appears to be linked to a sharp rise in the amount of deep convective clouds associated with the Pacific storm track.

.
Get Our Free Newsletters Via Email
  



  • Relief Flows Into Indonesia Quake Area As Death Toll Revised Down
  • More Chinese Arriving In Tibet With New Railway
  • Global Disaster Bill Declines In 2006 Says Swiss Re
  • Death And Destruction After Powerful Indonesia Quake

  • Climate Shifts And The Probability Of Randomness
  • EU Summit Seeks Unity On Tackling Global Warming
  • Banning New Coal Power Plants Will Slow Warming
  • The U.N.'s War On Global Warming

  • Space Scientists To Take The Pulse Of Planet Earth
  • Climate Change View Clearer With New Oceans Satellite
  • Satellite Scientists Set To Descend On Hobart
  • CSIRO Imagery Shows Outer Great Barrier Reef At Risk From River Plumes

  • Unlocking The Secrets Of High-Temperature Superconductors
  • China Bans New Small Coal-Based Power Generators
  • Progress Made in Biomass-to-Biofuels Conversion Process
  • Wen Says China Must Stop Wasting Energy

  • A Year Of Added Life More Valuable For The Young
  • Researchers Reconstruct Spread Of Bird Flu From China
  • Troubling Trends In AIDS Cases
  • Two Weapons Ready For AIDS Fight

  • Remote Sheep Population Resists Genetic Drift
  • Social Tolerance Allows Bonobos To Outperform Chimpanzees On A Cooperative Task
  • Why Do Birds Migrate
  • Some Corals Might Be Able To Fight The Heat

  • Bacterium Could Treat PCBs Without The Need For Dredging
  • Asian Pollution Linked To Stronger Pacific Storm System
  • Canada's Oil Sands To Keep Polluting
  • As An Economy Blossoms An Ancient Capital Suffocates

  • Could Baby Boomers Be Approaching Retirement In Worse Shape Than Their Predecessors
  • Time For TV Detox
  • DNA Study Explains Unique Diversity Among Melanesians
  • Eating Ice Cream May Help Women To Conceive But Low-Fat Dairy Foods May Increase Infertility Risk

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement