found to eat toxic waste
Microbe works in water underground, neutralizes a chemical pollutant
Scientists have identified a microbe that
gobbles up toxic waste deep underground, offering a potential way to clean up a
particularly nasty chemical that has contaminated the water under hundreds of
the nation's industrial and military sites.
Frank Loeffler said the bacterium, known as BAV1, was
found in soil samples 20 feet down at a hazardous waste site in Oscoda, Mich. BAV1
flourishes in the packed earth where there is no oxygen, feeding off certain
toxic compounds, he said.
microbes that eat toxic waste have been discovered over the years and are used
in some limited fashion to clean up contaminated sites. However, this is the
first one found that thrives on vinyl chloride underground.
chloride is one of the most common and hazardous industrial chemicals. It can
linger in the soil for hundreds of years and is present at about a third of the
toxic Superfund sites listed by the Environmental Protection Agency. It usually
accumulates as a deteriorated form of more complex compounds found in dry
cleaning fluid and metal cleansers.
contact with vinyl chloride can cause dizziness, drowsiness and headaches. Long-term
exposure can raise the risk of a rare form of liver cancer, according to the
Loeffler has already tested the bacterium on vinyl
chloride at the contaminated site in
work is presented in today's issue of the journal Nature.
Loeffler said the use of the microbes requires
only the approval of the land owner. He said the microbe remains in the soil,
and even when used in large concentrations, it has been shown not to harm
organisms can only grow when the contaminants are present," he said. "When
the material is gone, their numbers decline because they don't have any food. So really
it's a perfect system."
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.
hazardous chemicals have a way of sticking to the soil underground, so pumping
out the aquifer never quite gets rid of all the contaminants, Loeffler said.
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.
said the discovery will help scientists determine which enzyme breaks down
vinyl chloride. If the enzyme is found, he 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.