Real Time PCR for Clostridium botulinum detection in canned food

Food production processes are designed with food safety in mind. The process of canning or retorting exposes food in a hermetically sealed container to high temperatures for specific times determined to make the product commercially sterile. Clostridium botulinum is anaerobic spore-forming pathogenic bacteria that produces the botulinum neurotoxin. If temperature and holding time are not correct, the spores of the bacteria can germinate in the product after processing.

In a Hazard Analysis Critical Control Point (HACCP) plan, a critical control point (CCP) is a point in the process, that if performed incorrectly could lead to consumer harm. This must be validated with testing. In canning, the testing for Clostridium botulinum is a standard CCP test.

Polymerase Chain Reaction (PCR) is a technique used to target a specific DNA sequence and amplify it for identification. DNA, taq polymerase, primers and nucleotide bases are inserted into the PCR apparatus in a small vial. The vial is exposed to temperatures high enough to split the DNA strands. The temperature is lowered, and the primers bind to the DNA strands. The polymerase then allows nucleotide bases to continue binding to complementary bases on the DNA strand and form a duplicate strand. This process is repeated several times to create multiple copies. In real time PCR, the DNA fluoresces as it replicates. This fluorescence is measured as the PCR process happens. As such it is possible to see results as the amplification occurs by how quickly the fluorescence increases.

The use of real-time PCR to rapidly detect the presence of Clostridium botulinum works by targeting and amplifying sequences that are responsible for expression of the botulinum toxin. This allows clearance of product in hours rather than days.