prevalence of toxigenic bacteria in some egyptian food abstract ...

118PREVALENCE OF TOXIGENIC BACTERIA IN SOME EGYPTIAN FOOD(Soriano et al., 2002). Twenty different types of SEs, viz., SEA through SEE, SEG throughSER and SEU have already been discovered, however, only a few of the toxin serotypes arefrequently associated with food poisoning outbreaks (Martin et al., 2004; Smyth et al., 2005and Fernández et al., 2006).M 1 2 3 4695bp565bpPhoto(3): Agarose gel showing the PCR amplicons resulting from amplification of enterotoxins genes hblCand cytK using FHblC & RHblC and FCytk & R2Cytk primers. Lane M is 100bp DNA ladder marker;lanes 1,2,3&4 DNA amplicons of B. cereus G8,LB3 ,GT13&CH respectively. The gel reveals presence ofboth enterotoxin genes (hblC &cytK) in strainsGT1, LB3 & G8.Multiplex PCR technique has been recently used for rapid detection anddiscrimination of enterotoxins genes in B. cereus (Guinebretiere et al., 2006 andNagmwongsatit et al., 2008); and for direct detection of food contamination withenterotoxigenic B. cereus as well (Ombui et al. 2008).Ngmwongsatit et al. (2008) have developed and evaluated group of new primerswhich were highly efficient in detecting the toxin genes in 100% of their tested B. cereus andB. thuringensis strains. Thus, it could be expected that the presence of either genes is anindication for the presence of the whole operon.In this study the primers designed by Ngmwongsatit et al. (2008) were used underspecific multiplex PCR conditions, previously mentioned in materials and methods, to detectpresence of the enterotoxin genes (hblC &cytK) in tested strains. Photo (3) revealed presenceof amplified DNA fragments of the two toxin genes in three strains of B. cereus (CH, GT1 &G8) in one quick step. The toxin genes hblC & cytK predicted molecular sizes of 695 & 565bp, respectively.