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

116PREVALENCE OF TOXIGENIC BACTERIA IN SOME EGYPTIAN FOODPhoto(2): Polyacrylamide gel electrophoresis showing the protein pattern of cell free filtrates of the selected toxigenic 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 strainsCH, GT1,LB3 & G8 and lanes (5,6,7,&8) :S.aureus strains S, S1, S2, S3.Table(5): Similarity percentage betweenselected B. cereus strainsStrains CH GT1 LB3 G8CH 100 80 60 60GT1 80 100 80 60LB3 43 57 100 71.4G8 50 50 83.3 100Table(6): Similarity percentage betweenselected S. aureus strainsStrains S S1 S2 S3S 100 100 66.7 66.7S1 75 100 50 50S2 50 50 100 50S3 50 50 50 100Also, the pro-analysis of the extracellular protein bands of the tested isolates revealedvarying similarity between the virulent strains ranging between50 to 83.3% in B. cereus andbetween 50 to 75% in S. aureus (tables5&6). Photo (2) showed obvious protein bands in lanes1,2,3&4 having molecular weights (19.26, 30.24, 33.98, 53.44 & 72.59 kDa) ; (19.6, 30. 12,33, 75, 35.53 & 53.19 kDa); (22.11, 30. 03, 33,67, 35.08, 43.24, 53.14 & 234.36 kDa)&(19.63,22.77, 30. 93, 33,53, 43.23 & 234.36 kDa); in case of B. cereus strains CH,GT1,LB3&G8, respectively. Meanwhile S. aureus strains S, S1, S2&S3 possessedextracellular proteins with molecular weights (43.23, 93.486& 234.36kDa); (22.82, 43.54,53.676& 234.36kDa); (22.67, 33.21, 43.57 & 92.19kDa) & (30.39, 33.31, 43.74 &234.36kDa), respectively.Beecher and MacMillan (1990&1991) reported that molecular weights of B. cereusenterotoxin proteins were 35, 36 and 45 kDa for binding protein B, lytic protein L1 (HBLD)and lytic protein L2 (HBLC), respectively. Beecher and Wong (1994) also found that themolecular weight of B component was 37.8kDa, L1 was 38.5kDa and L2 was 43.2kDa.Schoeni and Wong (1999) reported that the three components isolated from prototype strainof B. cereus F837/76 have molecular weights of 37.5, 38.2 and 43.5 kDa, respectively. Theyalso added that an individual strain could produce single or multiple bands of eachcomponent. They observed two bands (38&42kDa) for B protein, two L1proteins(38&41kDa) and two L2 proteins (both 43kDa) in a soil isolate encoded S1C strain.