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

114PREVALENCE OF TOXIGENIC BACTERIA IN SOME EGYPTIAN FOODliving organisms (Smith, 1997 and Wong and Hancock, 2000). In this study, total cellularproteins of selected virulent strains of B. cereus (GT1, CH, LB3 & G8) and S. aureus(S, S1,S2 & S3) were extracted and then fractionated by means of polyacrylamide gelelectrophoresis. The electrophoretic separation verifying protein patterns of selected strainsrevealed protein bands with molecular weights ranging between 33 to 108 kDa in case of B.cereus strains and between 17 to 220 kDa in case of S. aureus (Photo 1). Using gel proanalyzer the gel photo had been analyzed and revealed varying similarity percentages withinB. cereus strains between 20 to 90% and between 63.2 to 82.4% in S. aureus ). Also,difference in number of separated cellular protein bands in the investigated strains wasobserved (fig1). B. cereus GT1 showed 9 protein bands while B. cereus G8 showed only 7bands. Concerning S. aureus strains S & S3 showed 19 bands and strains S1 & S2 17bands.Photo(1): Polyacrylamide gel electrophoresis showing the cellular protein pattern of virulent isolates.M: protein marker (mixture of 7 purified proteins with mol. wt. 116,97.4,66.2,37.6,28.5,18.4 and 14 kDa.Lanes (1,2,3 &4): B.cereus strainsGH, GT1, LB3, G8. and lanes (5,6,7,&8) :S.aureus strains S, S1, S2, S3.Table(3): Similarity percentage betweenselected B. cereus strainsTable(4):Similarity percentage betweenselected S. aureus strainsStrains S S1 S2 S3S 100 80 73.7 63.2S1 80 100 84.2 68.4S2 82.4 82.4 100 70.1S3 63.2 68.4 63.2 100Strains CH GT1 LB3 G8CH 100 89 33.3 44.4GT1 90 100 20 40LB3 30 20 100 20G8 57.1 57.1 28.6 100