http://www.msnbc.com/news/933922.asp?cp1=1
Microbe gobbles toxic plastic waste
Researchers see new approach to removing vinyl chloride
ASSOCIATED PRESS
July 2 - Scientists have identified a microbe that gobbles up toxic
waste deep underground, a potential remedy for hundreds of contaminated
aquifers across the country near industrial and military sites. The bacterium,
known as BAV1, was found in soil samples 20 feet deep at a contaminated site
in Oscoda, Mich.
MICROBIOLOGIST FRANK Loeffler of Georgia Tech University said it
flourishes in the packed earth where there is no oxygen, feeding off toxic
compounds commonly known for making plastic pipe and food wrap.
Most importantly, it thrives underground on vinyl chloride, one of the
most common and hazardous industrial chemicals that can linger in the soil for
hundreds of years.
Vinyl chloride is present at about a third of toxic "Superfund" sites
listed by the Environmental Protection Agency. It usually accumulates as a
deteriorated form of more complex organic compounds found in dry cleaning
fluid and metal cleansers.
Brief contact with vinyl chloride has been known to cause dizziness,
drowsiness, and headaches. Long-term exposure will increase the risk of a rare
form of liver cancer, according to the EPA.
Loeffler has already tested the bacterium on vinyl chloride at the
contaminated site in Michigan. Its ability to eat the toxic compound -
rendering it harmless - was hastened in one test by adding plant fertilizer
and other nutrients to the soil. In another trial, vinyl chloride was
destroyed by injecting the soil with concentrated amounts of BAV1 developed in
the lab.
His work is presented in Thursday's issue of the journal Nature.
"It's pretty exciting stuff," said David Freedman, an environmental
engineering professor at Clemson University who wasn't involved in the work.
The way most cleanup crews now deal with vinyl chloride is to pump the
contaminated water out of the ground and spray it into the atmosphere as a
fine mist, letting sunlight break down the chemical naturally.
"But through a very long and painful experience, we've learned that
it's not the best way to deal with the problem," Freedman said.
Hazardous chemicals have a way of sticking to the soil underground, so
pumping out the aquifer never quite gets rid of all the contaminants, he
explained.
"It's a waste of money," Loeffler said.
Scientists have long suspected that deep in the ground some type of
microbe found vinyl chloride palatable. Loeffler spent four years searching
for it, isolating BAV1 from a bustling community of microscopic organisms that
included thousands of kinds of bacteria.
James Gossett, a Cornell University researcher who identified a
bacterium in 1997 that could eat organic chlorides but had problems with vinyl
chloride, called BAV1 "another in a long list of discoveries or isolations"
that will illuminate research into cleaning toxic waste with bacteria.
Gossett said the discovery will help scientists determine which enzyme
breaks down vinyl chloride.
If the enzyme is found, Gossett said more robust bacteria that can
survive in the presence of oxygen or eat faster than BAV1 could be genetically
engineered to digest vinyl chloride.
BAV1 was isolated from a bustling community of microscopic organisms that
included thousands of kinds of bacteria.
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