POLYMERASE CHAIN-REACTION FOR THE RAPID IDENTIFICATION OF CLOSTRIDIUM-BOTULINUM TYPE-A STRAINS AND DETECTION IN FOOD SAMPLES

A polymerase chain reaction (PCR) was developed for the detection of C lostridium botulinum type A, a cause of human botulism. A two primer s et and an oligonucleotide detection probe were used to specifically de tect Cl. botulinum type A neurotoxin gene, (BoNT/A). After 40 cycles o f amplification, detection of a 798 bp amplified DNA fragment was carr ied out by agarose gel electrophoresis and Southern blot hybridization . This assay was able to detect 12.5 fg of purified target DNA or five bacteria per reaction. The sensitivity in artificially contaminated f ood samples after an 18 h enrichment step ranges from 10 to 10(3) bact eria per g according to the type of food samples. No cross-reactions w ere observed with the other Cl. botulinum toxinotypes and other bacter ia found routinely in food. This PCR method may provide a suitable and rapid alternative to standard techniques for detection of Cl. botulin um type A in food samples.