- The Washington Times - Wednesday, July 2, 2003


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 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 important, 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.

Mr. Loeffler already has 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 today’s issue of the journal Nature.

“It’s pretty exciting stuff,” said David L. 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,” Mr. 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,” Mr. Loeffler said.

Scientists have long suspected that deep in the ground some type of microbe found vinyl chloride palatable. Mr. 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.

Mr. Gossett said the discovery will help scientists determine which enzyme breaks down vinyl chloride.

If the enzyme is found, Mr. 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.

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