Presenting a rapid method for detection of Bacillus cereus, Listeria monocytogenes and Campylobacter jejuni in food samples

Abstract

<strong><em>Objective(s)</em>: </strong><em>Listeria monocytogens</em><em>, Bacillus cereus</em> and <em>Campylobacter jejuni</em> are three toxin producing bacteria over the world, especially in Iran, and it is essential to find a certain, rapid procedure to identify these microorganisms. In this research, these bacteria were simultaneously detected by multiplex PCR technique in foods.<br /> <em><strong>Materials and Methods:</strong> </em>The primary approval of bacterial strains was performed by biochemical tests. PCR primers were designed based on the nucleotide sequences of the <em>NHEB/NHEC </em>gene of <em>B</em>. <em>cereus,</em> the <em>hly</em> gene of <em>L. monocytogenes</em> and the C gene of <em>C. jejuni</em>. The specificity of Multiplex PCR method was determined using seven food poisoning bacteria including <em>Salmonella typhi, Shigella dysentery, Yersinia pestis, Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum and Vibrio cholerae</em>. To confirm the reaction, DNA extraction was performed from 30 food samples (milk), and gene amplification was performed by PCR. The length of amplified fragments was 300 bp, 210 bp and 160 bpfor<em> NHEB/NHEC</em>, <em>hly</em> and <em>C</em> genes, respectively.<br /> <strong><em>Results:</em> </strong>The detection limits of the PCR method were 5, 4 and 3 pg for <em>L. monocytogenes</em>, <em>B. cereus</em> and <em>C. jejuni</em>, respectively. Specifisity test showed that this reaction is spesific to these 3 bacteria.<br /> <strong><em>Conclusion: </em></strong>In this study, we introduced a new multiplex PCR method for simultsnus detection of <em>L. monocytogens, B. cereus</em> and <em>C. jejuni</em>. These results can be used for detection of other toxin producing bacteria in food.