Researchers at Purdue University in West Lafayette, Ind., have developed a new technology that can simultaneously screen thousands of samples of food or water for several dangerous food-borne pathogens in one to two hours.

The technique, which has potential biosecurity and food safety applications, also can estimate the number of microbes present and whether they pose a health risk.

"For food safety and biosecurity purposes, you need a quick test—a first line of defense—to be able to tell if there is something pathogenic in the food or water," says Arun Bhunia, a Purdue professor of food science.

The technology uses live mammalian cells that release a measurable amount of a signaling chemical when harmed. Optical equipment and computer software can analyze this quantity to estimate the amount of harmful microbes present, Bhunia says.

"With many toxins or pathogens, there is an effective dose or threshold you must pass before you have to worry," he says. "By providing information on quantity, this technology gives you a higher degree of confidence in the test and what steps must be taken to alleviate the problem."

The technology can recognize very small amounts of Listeria monocytogenes, a bacterium that kills one in five infected and is the leading cause of food-borne illness. It also recognizes several species of Bacillus, a non-fatal but common cause of food-poisoning, says Pratik Banerjee, a Purdue researcher.

By using live cells, called biosensors, this technology can identify actively harmful pathogens but ignore those that are inactive, or harmless. Some other tests lack this capability, making them prone to false alarms and entailing a relatively lengthy incubation period to grow out any living microbes, Banerjee says.

Another advantage to the technique is its mobility and versatility, Bhunia says. The multi-well plates and their contents of gel-suspended mammalian cells could be efficiently prepared in a central location. When desired, the plates could then be shipped to the test location, like a food processing plant, so that analysis could take place on-site, he says.

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