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An electronic nose may sniff out harmful bacteria on farms and in food products if research at Michigan State University is successful.

E. coli, Salmonella and other pathogens give off unique combinations of gases. The researchers want to know if those combina-tions are unique enough so that the pathogens can be identified by them and they want to know if electronic noses can be sensitive enough to tell the difference, says Spring Younts, a student working on the project.

Currently, researchers have to take samples of feed, water, feces or meat, isolate bacteria from them, and culture the bacteria to identify them -- a labor-intensive process that can take days. "We want something that's useable in the field with cattle or in the processing plant."

What Younts and her colleagues hope for is a portable "breath test" for feed, water, meat and other substances that may harbor dangerous bacteria.

Preliminary laboratory work has been promising, Younts says. Researchers have been able to detect distinctive differences in the gases given off by pure cultures of bacteria. Next they will test a wider variety of bacteria to confirm that individual strains of bacteria have unique gaseous signatures.

People and animals normally have colonies of E. coli living in their intestines, it's the invasion of the pathogenic form E. coli 0157:H7 that causes problems, Younts explains. "We need to know if we can distinguish the harmless from the harmful ones," she says.

Dan Grooms of the MSU College of Veterinary Medicine's Department of Large Animal Clinical Medicine and MSU meat scientist Wes Osburn are involved in the laboratory research into the gases given off by the bacteria.

Evangelyn Alocilja, a researcher in MSU's Agricultural and Biosystems Engineering Department has been working with Younts to adapt electronic nose technology to this new application in food safety.

The electronic nose collects the gases, analyzes them and feeds the data into a computer program. This program is designed to recognize specific patterns. It then accumulates data from each test performed so that subsequent tests become increasingly more accurate. In a way, the program "learns" to identify specific gases and calculates a probability that the gases are related to the presence of E. coli.

Other problems lurk, Younts notes. Gas emissions from bacteria may change depending on their growth medium. Combinations of bacteria may make it challenging for the electronic nose to identify a single pathogen.

"Still there is enough promise to pursue this as a possible field diagnostic tool or a tool that could help us enhance other tests for detecting bacteria," Younts says. "What we're ultimately looking for is immediate feed-back."


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