UF Develops Test To Pinpoint Causes Of Water Pollution

January 6, 1999

GAINESVILLE — University of Florida researchers have developed new tests to determine causes of pollution in lakes, streams, bays and underground water supplies.

Inexpensive and highly reliable, the tests combine DNA fingerprinting techniques like those used in criminal investigations with tests for antibiotic resistance.

“Until now, it has been difficult to determine if germs in water are coming from human or animal sources,” said Tamplin, food safety expert with UF’s Institute of Food and Agricultural Sciences. “Our new tests are 99.9 percent reliable in determining whether animal or human waste is causing high levels of bacteria in polluted water.

“This testing is important in communities that have been concerned about water contamination and building new sewers,” Tamplin said. “People on septic tanks point the finger at farmers and wildlife as the cause of pollution, and farmers point their finger at the septic tanks.”

The tests capitalize on the fact that DNA patterns of human E. coli bacteria are different from those in animals and that many E. coli in humans have become resistant to antibiotics.

“The current tests for E. coli only measure the amount of the bacteria but do not give any indication of whether it is from animals or humans,” Tamplin said. “If water contains E. coli from humans, there’s a potential for diseases such as salmonella and hepatitis to be present,” Tamplin said. “If there are no E. coli from humans, there’s little chance of the water transmitting human disease.

“Our new tests can help prioritize where to put money. We need all the tools we can get to clean up America’s water.”

The UF tests were first used in White County in north central Indiana. The tests, which White County officials discovered on the Internet, are helping settle an argument about whether septic tanks, wildlife or pig farms are causing dangerously high E. coli counts around the Lake Shafer resort area.

Thirty-five of the 41 sites had both E. coli from both humans and animals, and the remaining six sites had E. coli only from animals. “The results indicate you can’t just point one finger. Everybody is part of the problem,” Tamplin said.

“The tests are a good buy,” said Alan Shookman, White County environmental health specialist. “Their total cost of $18,500 is a small price compared with the multimillion dollar projected cost of the first phase of a proposed septic tank replacement program in the county — a proposal covering 900 lakefront homes.

“The tests showed that yes, there is human involvement,” he said. “We’re going after both the septic tanks and agricultural runoff in our cleanup efforts.”

Tamplin has a second testing project in the works. He is developing a contract with Broward County to test the effects of dog feces in waterways.

UF’s tests grew out of studies of bacteria that were contaminating oysters in Apalachicola Bay in North Florida. “As we got into the studies, we began to focus on E. coli because they are present in all warm-blooded animals and are a good mechanism for tracing the source of pollution,” Tamplin said.

Tamplin’s research team developed profiles of the E. coli found in humans and animals by testing more than 1,000 strains of the bacteria from the waters around Apalachicola Bay and comparing them with 300 samples from Rookery Bay near Naples.

“We were pleasantly surprised that the profile we developed in Apalachicola Bay matched the Rookery Bay samples and can be used in other parts of the country,” Tamplin said.

The antibiotic resistance test is based on the tendency of the E. coli present in humans to mutate and become resistant to a variety of antibiotics. “If the E. coli in a sample is not resistant to antibiotics, it probably comes from animals,” Tamplin said.

Another UF testing procedure using DNA fingerprinting can determine whether particular sewage treatment plants or septic tanks are responsible for a water pollution outbreak. “With this test, we can pinpoint problems to a specific source, which is important when determining responsibility,” Tamplin said.

“This technique is a godsend to pollution regulators,” said Todd Hopkins, an environmental specialist with the Rookery Bay National Estuarine Research Reserve Program.

Researchers at the 21 other National Estuarine program sites around the country were pleased when he told them of the UF research, Hopkins said. “They were excited about this breakthrough,” he said. “One of the biggest problems in water pollution is our inability to pinpoint its origin.”