Bacterial Strain May Help Clean Up Harmful Industrial Waste

Under his microscope is a bacterial strain called T1 capable of breaking down one of the most commonly used industrial solvents, toluene. A common but toxic ingredient in gasoline, adhesives and household solvents, the substance has been known to contaminate groundwater and soil.

"A lot of current cleanup techniques involve taking all the contaminated soil from a site and hauling it off somewhere and dumping it or burning it," says Peter Coschigano, an assistant professor of environmental microbiology and lead investigator on this National Science Foundation-funded project. "That if you talk about tons and tons of soil can be expensive, and you're left with a big hole in the ground."

But environmental remediation professionals might be able to avoid pockmarking the earth if researchers can understand what conditions must exist for bacterial strains such as T1 to digest dangerous contaminants.

"The potential is that it can be more cost-effective and less damaging to the environment," says Coschigano, whose research appears in the March issue of the journal Applied and Environmental Microbiology.

T1 metabolizes toluene, a hazardous substance widely used as an industrial solvent. Though toluene can enter the environment via spilled drops of gas at the filling station, the use of paint thinners, or small industrial leaks, the bigger health and environmental threat would be a large-scale industrial accident, which can contaminate groundwater and soil.

Researchers at the New York University Medical Center discovered the bacterial strain T1 about 10 years ago, digging through the mud at contaminated sites in search of an organism in the natural environment that could break down toluene without oxygen, which is absent in some polluted areas. Coschigano is investigating how T1 metabolizes the substance, what genes are involved, and how the process is turned on and off.

He has confirmed the first step in T1's use of toluene for fuel: Proteins produced from four genes under examination are responsible for carrying out the process. Three of the proteins, which work together as a team, are activated by a fourth protein. "They are all needed to do the work," he says. "Just like a car needs an engine, brakes and tires to work." Coschigano also has detected a fifth, previously unidentified gene in the bacterium, but doesn't know what role if any it plays.

Coschigano studies how the bacterial strain regulates its metabolism of toluene by testing T1 on pyruvate, a carbon substance with a much different structural composition than toluene. When the bacterial strain is grown on pyruvate, the genes responsible for metabolism don't switch on, unlike the activity seen when the bacterial strain is bred on toluene.

Even if Coschigano determines how to control T1's appetite for toluene in the lab, he doesn't know how efficiently the bacterial strain will clean up contaminants in the complex natural environment. A more predictable, easier and cheaper option might be to unleash T1 on toluene in a contained, industrial setting before toluene has a chance to escape into the environment.

"Toluene is one of the most widely-used industrial solvents," he says. "There can be situations where companies have a lot of toluene waste they need to dispose of. And instead of incinerating it, if we can deal with it in a contained system, we might be able to reduce that cost."

Coschigano received a five-year Faculty Early Career Development (CAREER) grant from the NSF in 1998. He holds an appointment in the College of Osteopathic Medicine.