Detection of bacillus cereus isolates from goat’s milk with conventional and pcr methods

Document Type : Original Articles

Abstract

cereus is a gram-positive spore-forming rod that is ubiquitous in the environment. B. cereus is a common contaminant in dairy products. Food poisonings from the consumption of B. cereus-contaminated milk products have been reported. So, the aim of this study was establishing an easy and accurate method for detection and
identification of this pathogen. Therefore, eighty raw milk samples were collected from d!fferent locations (El-Arish vally, El-Shekh .ZOid, Rajah, Al-Qosima and Nekhle) where shami goats are raised under grassing conditions representing the extensive system in north siai governorate Physiological features were studied including lecilhinase activ­ity and an assay based on the PCR’ has been developed lo facilitate lhe detection and ’identification of B. cereus in milk. Two pairs for the PCR have been designed w ithin the sequence for cereolysin A (cerA), a cy toly tic determinant that encodes lecithin hydrolyzing of B. cereus. The organism w. isolated from 33 raw milk samples (41%) from which 28 samples (84%) produced lecithinase enzy me by conventional culturing meth­ od , while 5 samples ( 15%) did not show lecithinase activity. With PCR assay. all isolated strains of B. cereus gave amplification of the cerA gene with selected primers (PJ-Pr). Results demonstrate a high specificity of the primers selected for isolates of B. cereus

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