Determination of Enterotoxigenic Gene Profiles of Bacillus cereus Strains Isolated From Dairy Desserts by Multiplex PCR

Abstract

The aim of this study was to investigate the presence of Bacillus cereus and to detect enterotoxigenic genes in dairy dessert samples utilising a multiplex PCR technique. A total of 100 samples, 25 keskul, 12 tavuk gogsu, 12 kazandibi, 30 supangle, 4 profiteroles and 17 sutlac were analysed. B. cereus contamination was found in 7 of 100 (7.0%) samples including 3 (25%) tavuk gogsu, 2 (6.6%) supangle, 1 (4%) keskul and 1 (5.8%) sutlac. The average number of B. cereus was between 2.0×101 - 5.0×102 cfu/g in these dairy dessert samples. A total of 20 isolates were collected from the 7 positive samples. The results indicated that 30% (6/20) of B. cereus isolates contain three enterotoxic HBL complex encoding genes hblA, hblC and hblD, whereas 70% (14/20) had no hbl genes. In addition, all three enterotoxic NHE complex encoding genes, nheA, nheB and nheC, were detected in 40% (8/20), two nhe genes (nheA and nheB) were found in 45% (9/20) and one nhe gene (two nheA and one nheB) was found in 15% (3/20) of the isolates. The ctyK1 gene was not detected in any sample. The presence of B. cereus and their enterotoxigenic genes in dairy desserts may be a potential risk for public health.