Public release date: 6-Jan-2002
Contact: Steve Berberich
[email protected]
301-738-6295
University of Maryland
Biotechnology Institute
Microbe first to break down PCBs
BALTIMORE, Md. --A first strain of bacterium that
breaks down tough chlorine bonds of the pollutant PCBs,
polychlorinated biphenyls, in estuarine sediment is reported in the
current issue of the journal Environmental Microbiology by scientists
with the University of Maryland Biotechnology (UMBI).
In experiments repeated many times on bottom sediments
from Baltimore harbor, researchers of UMBI's Center of Marine
Biotechnology (COMB) and the Medical University of South Carolina
(MUSC), discovered the PCB-degrading bacterium using a rapid, DNA
screening method.
For several decades, environmentalists and regulators
have been challenged to deal with tons of banned PCBs in the
environment, released by industries for over 70 years. "This
first identification of a PCB-dechlorinating, anaerobic (without
oxygen) bacterium is important for bioremediation efforts and for
developing molecular probes to monitor PCB degrading where they are
found," says Kevin Sowers, research microbiologist at COMB. The
researchers linked PCB dechlorination directly to the growth of the
bacterium. It appears to live off the compound.
Jennie Hunter-Cevera, UMBI president and environmental
biotechnologist, adds, "This is a great example of how man-made
pollution can be handled by microorganisms through their incredible
ability to adapt." The report concludes that the UMBI method
could be used to identify additional PCB-degrading microbes.
Beginning in the 19th century, PCBs were made from petroleum as
insulators for electrical equipment and other electronics. But, in
1979, the federal government banned them because of possible
environment and human health hazards.
However, all over the world, says Sowers, PCBs are
still bound to bottom sediments of many rivers, harbors and bays.
"Particles of PCBs persist after many years, because they don't
dissolve well in water. They attach to sediment and get covered
over," he says. "Unless there is some turnover, a lot of
PCBs stay hidden." The hazardous pollutants can build up in fish
and marine mammals, in which PCBs can reach thousands of times higher
levels than in the water they live in, according to the U.S.
Environmental Protection Agency.
The researchers chose a site near a former electrical
power plant in Baltimore where levels of up to two parts PCB's per
million in harbor sediments have been found. PCBs are found at many
industrial sites.
The bacterium catalyzes dechlorination of PCBs. Until
recently, few bacteria species had been described by scientists that
"reduce" chlorinated organic molecules of any kind. Today
several are known. However, the bacterium in UMBI/ MUSC study is the
first found to break the chlorine bonds in the critical ortho
position, say the researchers. The distinction raises hopes for the
potential complete dechlorination of persistent molecules. "To
develop bioremediation technology, this sort of discover is
particularly exciting. It integrates modern tools of biotechnology
and molecular screening with a keen understanding of microbial
ecology," observes Hunter-Cevera. PCBs are either oily liquids
or solids that are odorless, tasteless and nearly colorless.
Before being banned, they freely entered the air,
water and soil during their manufacture, use and disposal. Although
often buried in anaerobic river and coastal mud, PCB contaminated
particles get released when disturbed by natural currents and tides,
burrowing activity of aquatic animals and dredging.
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The University of Maryland Biotechnology Institute was
mandated by the state of Maryland legislature in 1985 as "a new
paradigm of state economic development in biotech-related
sciences." With five major research and education centers across
Maryland, UMBI is dedicated to advancing the frontiers of
biotechnology. The names of the UMBI centers are the Center for
Advanced Research in Biotechnology in Rockville; Center for
Agricultural Biotechnology in College Park; and Center of Marine
Biotechnology, Medical Biotechnology Center, and the Institute of
Human Virology, all in Baltimore.
Public Concern Temiskaming
http://members.fortunecity.com/toxic/
Swan Hills Waste Treatment Centre
http://www.health.gov.ab.ca/informat/swan.htm
PCB Information
http://www21.brinkster.com/nopcb/
Earth-Policy Institute
http://www.earth-policy.org/
Petition for Inquiry into the Death of Dudley George
http://www.nt.net/~savard/petition.htm
Aboriginal News
http://www.turtleisland.org/
HighGrader Magazine
[email protected]
http://www.grievousangels.com/highgrader/