Ten Years of Progress For Superfund Basic Research Program

February 24, 1997

A team of University of Cincinnati researchers that spans three colleges and five departments will report their progress in addressing some of the nation's most troubling pollution problems during a special conference Feb. 24-26 in Chapel Hill, North Carolina.

The National Institute of Environmental Health Sciences is sponsoring the conference to celebrate the 10th anniversary of the Superfund Basic Research Program. The University of Cincinnati was one of the first universities selected to take part in the program and has received more than $10 million in funding over the last eight years.

"We've pooled all this expertise," said Professor John Loper, who oversees the entire UC project. "It's only the only national, university-based and peer-reviewed program that addresses this important need at this level."

The University of Cincinnati program consists of several projects, but focuses primarily on risk assessment and bioremediation of compounds that don't degrade very readily in the environment.

One of the success stories to be presented in Chapel Hill is the isolation and characterization of a strain of bacteria from the genus Sphingomonas which is capable of breaking down compounds known as "N-heterocyclics." Many compounds in that group cause mutations and can lead to cancer. Brian Kinkle, assistant professor of biological sciences, says Sphingomonas shows great promise for bioremediation work.

"It's an interesting genus of bacteria they keep finding in more and more polluted sites. We find it in groundwater and soil. Different strains seem to degrade a wide variety of compounds."

A second organism isolated and studied at UC belongs to the genus Mycobacterium. This group includes the microbes which cause leprosy and tuberculosis, but the strain used at UC is a common soil bacteria which does not cause illness. What it can do is chew up another group of chemicals which can cause cancer and are not easily degraded in nature. They're called PAHs or poly- aromatic hydrocarbons.

"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 tin, arsenic and chromium. The key to accurate risk assessment is knowing not only how much metal is present, but the exact form the metal is in.

"For example, it's not uncommon for Gulf seafood to contain arsenic," explained Caruso. "That could be a concern; however, it's not, because the form of the arsenic is totally innocuous. Chromium is a similar case where Chromium III is essential to life, and chromium VI is toxic."

Caruso's research group published a paper last summer in the Journal of Analytical Atomic Spectrometry describing the methods used to detect sub-nanogram levels of organotin compounds in their gaseous form. His research is now being expanded to include liquid samples and solid samples, which would be useful in analyzing contaminated waters and harbor sediments.

Working at very low levels of detection is important for a number of reasons. First, many metals are toxic at very small quantities. Secondly, it makes the analysis more accurate and reliable because the chemists don't have to concentrate their samples. "The less we treat the sample, the more contamination-free it's going to be," summed up Caruso.

Researchers in the College of Medicine will also present their findings concerning the molecular and biochemical mechanisms of degradation and the mutagenesis of toxic metals. Kathleen Dixon, associate professor and associate director of the department of environmental health, will discuss her findings on the mutagenic mechanisms of chromium. She has looked at the links between chromium inhalation and lung cancer and has developed model systems including yeast, bacteria, mammalian cell cultures and transgenic mice. Dixon's presentation will be one of the featured talks during the three-day conference.

The complete UC research team includes 12 faculty in the departments of molecular genetics and environmental health in the College of Medicine, the departments of chemistry and biological sciences in the College of Arts and Sciences, and the department of civil and environmental engineering in the College of Engineering. UC's funding was recently extended through March of the year 2000.

University of Cincinnati

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