April 2, 2002

Researchers Develop E. coli Detection

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Instead of conducting bacteria tests that wield results in a few days, Prof. Richard A. Durst, chemistry, along with several colleagues, graduate students and research associates have developed a test capable of detecting E.coli in foods within minutes.

The research has been in progress for two years with funding from the U.S. Department of Agriculture’s Cooperative State Research and Extension Service, the Cornell Center for Biotechnology, New York State Energy Research and Development Authority, and Innovative Biotechnologies International.

Other members of the Agricultural Experiment Station in Geneva, N.Y. include Richard Montagna, president of Innovative Biotechnologies International Inc., and Prof. Anteje J. Baeumner, biotechnology.

E.coli is a deadly food-borne pathogen that causes hemorrhagic colitis (characterized by irregular bowel movements). It also causes hemolytic uremic syndrome, which usually affects children under the age of ten and causes the destruction of red blood cells, damage to the lining of blood vessel walls, and, in severe cases, kidney failure. The pathogen has been found in unpasteurized apple cider, unpasteurized apple juice, hamburger meat and water.

Researchers have tried to find faster methods of detecting E.coli for years.

“Basically, the faster you can detect the deadly pathogen, the faster you can tell if the food is safe to eat,” said Baeumner.

It used to take days to cultivate sufficient amounts of E.coli for testing but, recently researchers reduced that detection time to hours. Now, after two years of research, this time has been reduced to eight minutes with the development of a biosensor that “works like a home pregnancy test,” according to Durst.

However, this new biosensor only works for samples that are heavily contaminated with E.coli. For other samples that tend to have a lower concentration of E. coli, like apple juice or hamburgers, enrichment steps that take two to three hours are necessary to harvest a sufficient amount of E.coli for detection. This detection time is still less than the previous times due to the sensitivity of the new technology.

In one format of the new home pregnancy-like test, paper strips coated with vesicles that contain dye-filled marker molecules called liposomes, are put into a solution that is contaminated with E.coli. As the liquid is drawn up the strip and crosses the liposome-coated area, the E.coli gets bound to a receptor on the strip, and is simultaneously bound to the liposome. If E.coli is present, it causes the liposome membrane to rupture, signaling the release of the dye. This change in color of the test strip indicates the presence of E.coli.

Durst spoke about the new sensor at PITTCON 2002, an analytical technology conference at the Enrest N. Morial Convention Center in New Orleans on March 17. The convention attracted approximately 30,000 scientists, managers and exhibitors from more than 120 countries.

Durst spoke on the rapid methods for food safety and methods for detecting toxins and pathogens.

“It was the largest conference of its time in the world,” said Durst.

This new technology has been licensed by Cornell to Innovative Biotechnologies International, which has transferred it to field tests for Cryptosporidium parvum, an intestinal parasite that can be found in some waters and causes stomach problems. Due to the sensitivity of the technology, it can be used in a broad array of biosensors.

“It’s still a work in progress,” Durst said. “We’re trying to increase the sensitivity. We feel it would be a greater benefit to be able to anticipate contamination before it happens, then detect it afterwards.”

The team is now working on a micro Total Analysis System, a device in which all operations, including the detection of dilute E.coli solutions, can be automatically done on a laboratory chip within an hour.

“We want to work on something where people can detect E.coli in the field,” Baeumner said. “Eventually, we hope that people can buy these devices from stores.”

“Hopefully we can do this in one to two years,” Durst added.

Archived article by Sun Staff