New Method Detects Key Form of Botulinum Spores

Refrigerated convenience foods are growing in popularity, but they’re particularly vulnerable to a type of foodborne botulism caused by the form of the bacterium known as non-proteolytic Clostridium botulinum. That’s because, unlike the proteolytic strain, non-proteolytic C. botulinum can grow and produce toxin at refrigerated temperatures.

Now, scientists in the U.K. and Switzerland have developed a new method for detecting spores of non-proteolytic C. botulinum. The enrichment process is very sensitive, with a low detection rate, and can distinguish non-proteolytic C. botulinum from proteolytic C. botulinum, unlike some previous detection methods. It also allows calculation of the total risk from spores of non-proteolytic C. botulinum in the final meal.

“The detection rate could be as low as one spore per bottle,” said Mike Peck, PhD, professor of microbiology at the Institute of Food Research (IFR) in Norwich, England, which is sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC). IFR collaborated with the Nestlé Research Centre in Switzerland to develop the enrichment method, which combines a selective enrichment culture with multiplex polymerase chain reaction (PCR). Such a process is useful in pathogen detection because it enables the simultaneous amplification of many targets in one reaction.

“While it is very sensitive, our method is intended to seek out those large numbers of spores. If you’re designing improved processes to control this bacterium and know how many there are, you can utilize milder processes rather than having to assume the worst case all the time,” Dr. Peck said.

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