January 16, 2001

A new scientific tool designed to help ensure food products are free of bacteria like E. coli and Salmonella has been patented in Canada. The "rotary thermocycler" was developed by researchers at Agriculture and Agri-Food Canada's (AAFC) Food Research Program in Guelph, Ont. Its uses include detecting and counting bacteria, testing for bacterial contaminants in water and counting microbes in soil.

Researchers are hoping the system will allow for cell counts of specific bacteria to be obtained routinely in two hours, even if other bacteria are present in the same sample. Current methods of counting bacteria, such as growing and testing cultures, are slower and not all bacteria are easy to culture for this purpose.

The rotary thermocycler is a specialized polymerase chain reaction (PCR) machine that resembles a multi-disc CD player. The CD-like filters, on which bacteria have been trapped, are processed through several cycles of different temperatures and reactive conditions. The reaction products appear as spots on the filters. The number of spots is recorded by an electronic camera, which gives the cell count.

"This machine should be of great use in situations that require rapid enumeration of bacteria," says Greg Poushinsky, director of AAFC's Food Research Program. "In most areas, including agricultural and microbial research, the food industry, human and veterinary medicine and environmental risk analyses, there is a need for rapid and accurate screening methods."

AAFC has filed an application for an international patent for the rotary thermocycler. Research into its various applications is proceeding in collaboration with other AAFC research centres in Canada.

The Canadian Farm, an agricultural program that airs on CTV affiliated stations across Canada, will run a story on the rotary thermocycler Jan. 13 and 14.