"They're a big concern," said Kinkle. "They're often potent carcinogens. They bind to the DNA which can affect gene regulation."

Both bacterial strains were originally isolated from Superfund sites, specifically polluted soils located at coal gasification plants in Illinois. However, Kinkle says a great deal of work is needed to find the best way to use these microbes in the field where they will have to compete with other naturally occurring organisms.

Environmental engineering professor Paul Bishop is using other Sphingomonas strains to degrade another common pollutant, azo dyes. "The dyes themselves are not particularly harmful," said Bishop, "but when they're ingested, they're broken down by the bacteria inside you into carcinogenic materials."

Again, the main problem is that azo dyes are not readily degraded in nature. Bishop has designed bioreactors in his laboratory which use thin biofilms of Sphingomonas and other microbes to break down the dyes. He believes his novel two-step reactor will be much more effective than previous designs which required two separate reactors. It alternates between anaerobic (no oxygen) and aerobic (with oxygen) degradation to chew up the dyes more completely.

Bishop's group has also designed tiny probes which can measure the concentration of oxygen, hydrogen sulfide and other compounds in the biofilms. This is important, because some of these compounds can speed up degradation while others will kill off the organisms needed to degrade the azo dyes. "We can now probe the black box of the biofilm," said Loper, noting the significance of Bishop's work.

Analytical chemist Joe Caruso, Dean of the College of Arts and Sciences, is working on a separate project which should make it easier for government regulators to identify the most dangerous pollutants. Caruso is developing ultra-trace methods to detect metal pollutants including t
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Contact: Chris Curran
chris.curran@uc.edu
513-556-1806
University of Cincinnati
24-Feb-1997