Technology uses live cells to detect food-borne pathogens, toxins

Purdue researcher Pratik Banerjee, at left, measures fluid as he and professor of food science Arun Bhunia work in the lab. Their technology uses common lab materials to quickly screen... Click here for more information.

WEST LAFAYETTE, Ind. - Researchers 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 amount of microbes present and whether they pose an active health risk. This could help neutralize potential threats and improve food processing techniques, said Arun Bhunia, a professor of food science at Purdue University.

"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," Bhunia said.

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

"This is very important," he said. "With many toxins or pathogens, there is an effective dose or threshold you must pass before you have to worry. 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, said Pratik Banerjee, a Purdue researcher and first author of a study detailing the technology that is published in the February issue of the journal Laboratory Investigation.

The cells are suspended in collagen gel, a useful substance for capturing particles of a desired size, and put into small wells within multi-well plates. Each well can test one sample, so tests can be expanded to quickly analyze as many samples as desired.

By using live cells, called biosensors, this technology can identify actively harmful pathogens but ignore those that are inactive, or harmless. Some analogous tests lack this capability, making them prone to false alarms and entailing a relatively lengthy incubation period to grow out any living microbes, Banerjee said. The new technology's discerning power also could help optimize processes to kill harmful microbes or deactivate toxins, he said.