Newly identified poison-gulping bacteria could prove invaluable against the most common toxin found in aquifers, scientists say.
These low-cost microbes also could prove a boon for the $25 billion global pollution-fighting market, experts predict.
"Cleanup at contaminated sites is often very difficult to achieve and expensive with conventional approaches," microbiologist Frank Loeffler of the Georgia Institute of Technology explained to United Press International. "These microbes could have very important applications in the future for cleanup."
Using biology to detoxify or "remediate" pollutants is a roughly $500 million industry in the United States, said biotechnology analyst David Glass in Needham, Mass.
"It works for many contaminants, is a cost-efficient technology and treatment of large sites becomes feasible," Loeffler added.
Loeffler and colleagues found a microbe -- called BAV1 -- that eats organic pollutants loaded with chlorine, such as trichloroethylene, or TCE, a colorless liquid found in up to one-third of the nation's drinking water supplies.
The Centers for Disease Control and Prevention in Atlanta said TCE damages the nerves, kidneys and liver. Another such pollutant is tetrachloroethylene, or PCE, a known carcinogen.
"These chemicals first found use in large quantities in the 1920s. They are excellent solvents," Loeffler explained. "The big advantage of chlorinated solvents is they're not flammable, so they don't form explosive mixtures. Imagine you're at the dry cleaners, and someone walks in with a cigarette."
PCE is employed in dry cleaning, while TCE is used to degrease metal. Before regulations in the past 25 years strictly limited their use, TCE was used as an anesthetic and a pet food additive, the CDC noted.
"We found the microbes (BAV1) by a roadside in Michigan, where a dry cleaning facility dumped PCE for many years behind a building. These contaminants were spreading toward Lake Huron, 200 yards away," Loeffler recalled.
Loeffler reasoned that wherever the chlorine-loaded pollutants were found, so might dwell germs that lived off such toxins. It took years of effort from Loeffler and his team of microbiologists, hydrologists and engineers to isolate the disk-shaped bacterium BAV1, which is less than one-hundredth the width of a human hair in diameter.
Other microbes break down PCE and TCE as well, but the byproducts -- such as dichloroethenes and vinyl chloride -- also are potent toxins or carcinogens.
"Some of the most infamous contaminated sites in the U.S., such as Love Canal, had a lot of vinyl chloride," said Terry Hazen, the head of the Center for Environmental Biotechnology at Lawrence Berkeley National Laboratory in Berkeley, Calif.
BAV1 carries detoxification one step further by destroying these byproducts and yielding harmless ethene and inorganic chloride, the scientists reported in the July 3 issue of the British journal Nature.
The microbe lives off these artificial compounds even though as food the molecules pack little energy. If denied the chlorinated molecules, they die, Loeffler said.
"They could have evolved specifically to feed off these manmade contaminants," Loeffler said. But he suspects these molecules are, in fact, present in the environment naturally, only in extremely minute concentrations, and BAV1 is detectable now as it blooms and seizes advantage of the pollutants' unnatural abundance.
When the researchers injected some 200 billion BAV1 microbes into a contaminated test plot in Michigan, nearly 5,300 cubic feet in size, all the chlorinated molecules were detoxified in just six weeks by this "bioaugmentation" technique.
"There may be a real market for an organism like this," Hazen told UPI. For one thing, he noted this microbe can be grown fairly cheaply in a lab. More importantly, BAV1 works quickly. Glass noted existing non-biological methods to get rid of chlorinated ethenes can take years.
"If you can get reduction of contaminants within the first month, or first couple of weeks even, it's going to drive down overall costs," Hazen said. "And the owner might want to rapidly clean the site to remove deed restrictions so they can sell it or develop it. Another scenario is if there's an eminent risk, if a plume of the contaminants is threatening a drinking water well. Of course you'd want to get in there and clean it up as rapidly as possible."
Regenesis Bioremediation Products, a firm in San Clemente, Calif., that collaborated with Loeffler on this research, is marketing BAV1 as Bio-Dechlor. Glass noted any bioremediation technique normally faces a very tough road, since the remediation industry as a whole "is very resistant to innovation."
"(Still), Regenesis has been a successful company. They have an existing sales force that really knows this market. So if anybody could make it work, it'd be them," Glass told UPI. "I'll be guardedly optimistic."
In the meantime, Loeffler wants to better understand how BAV1 evolved and the biochemistry they use to live off these pollutants. He told UPI learning how to mimic what BAV1 does artificially could lead to new industrial techniques.
