Food Safety Magazine

News | March 6, 2017

Tuskegee Researchers Secure Patent for PCR Assay That Differentiates Between Live and Dead Bacteria

By Staff

Tuskegee Researchers Secure Patent for PCR Assay That Differentiates Between Live and Dead Bacteria

Researchers at Tuskegee University--a historically African American college in Alabama--have secured a patent for a faster and more efficient way to detect live bacteria that could contaminate the nation’s food supply.

U.S. Patent No. 9434976 was awarded to Tuskegee’s College of Veterinary Medicine. The invention is a method of determining whether an infectious, live microbe--such a bacteria--is present in a test sample. The researchers have determined how to differentiate live and dead bacteria by way of polymerase chain reaction (PCR) assay sample preparation.

This research project has been conducted by principal investigator Dr. Teshome Yehualaeshet, along with co-investigators Temesgen Samuel, Woubit S. Abdela, and Tsegaye Habtemariam. All are faculty members in the university’s College of Veterinary Medicine’s Department of Pathobiology.

According to Dr. Yehualaeshet:

“PCR has been developed decades back and the time spent for conventional PCR and our PCR — we call it viability PCR — protocol is the same. The novel aspect of our patent is that we developed a modified sample preparation, which enables the PCR to detect only viable, or live, bacteria. If a detection method could not differentiate the dead from the live bacteria then there is always a risk of false positive alarm,”

“This patent will be important to monitor cleaning, disinfection and sterilization processes, contaminated office or hospital rooms, recreational and drinking water sanitation, antibiotics efficacy and more. If there is no live organism after sterilization, it means the chemical used and the sterilization process works well. Therefore, the best detection technology should be able to detect only viable bacteria.”

“Various foods have been pasteurized to kill bacteria to make them safe for the consumer. Therefore, the bacteria present in food matrix may be dead due to the treatment but the DNA, which remains in the sample, turns the regular PCR result positive. Using our modified viability PCR, the presence of only viable bacteria will give positive PCR signal.”

In 2014, Tuskegee University researchers also secured a patent for a time-saving method of determining multiple foodborne and biothreat pathogens in food items such as meat, milk and vegetables.

The Tuskegee team’s research was funded by the National Center for Food Protection and Defense, which was renamed the Food Protection and Defense Institute.

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