ITHACA, N.Y. -- An antibiotic-resistant bacterium, isolated from sewer sludge by Cornell University scientists, is pointing the way to better water-pollution cleanup strategies.
The bacterium, coccoid Strain 195, perfectly reduces the toxic pollutants tetrachloroethene and trichloroethene (also known as PCE, or perc, and TCE, respectively) to nontoxic ethene gas, the Cornell researchers report in the June 6 issue of Science. But the talented bug alone may not be the magic bullet against the second-most-common ground water pollutant in North America.
Still, knowing how Strain 195 works its magic in the laboratory will lead to better pollution cleanup strategies in the field, predicted James M. Gossett, the Cornell professor of civil and environmental engineering who started Cornell microbiologist Stephen H. Zinder on the search for the perfect dechlorinator, a quest that began in a sewage treatment plant.
Zinder, a professor of microbiology, as well as graduate student Xavier Maymo-Gatell and other colleagues, used funding from the Cornell Center for Advanced Technology in Biotechnology and the U.S. Air Force to isolate Strain 195 from an enriched, mixed culture of bacteria that Gossett and his co-workers had developed from a sludge sample. The sludge came from Ithaca's old sewage-treatment plant, a microbe-rich relic from the days when dry-cleaning solvents and industrial degreasing agents were flushed down the drain.
An anaerobic bacterium, Strain 195, "uses tetrachloroethene much like we use oxygen," Zinder said, describing the reduction process that leaves little more than ethene, also known as ethylene, the natural gas that causes fruit to ripen.