Molecular typing of Bacillus cereus strains isolated from food

Objective To develop a molecular typing method of Bacillus cereus strain for tracing Bacillus cereus-induced food poisoning. Methods Totally 48 Bacillus cereus strains were isolated from outbreak or sporadic cases of food poisoning from 2000 through 2009 for the biological identification and biochemical typing.vrrA gene was amplified by PCR and sequenced.The results were analyzed with Bio-edit and MEGA analysis softw are. Results Forty-two strains were typed into 3 types known as type 2(34.04%),type 10(34.04%),and type 4(21.28%),while other 5 strains could not be typed by biochemical typing.Forty-seven strains were typed into 13 genotypes by molecular typing.Among the strains typed, MT13 is the main type(19 strains,40.43%);8(17.02%)strains are MT1,and 4(8.51%)strains are MT10. Conclusion vrrA gene could be used in the investigation of Bacillus cereus DNA molecular typing and could be considered as a polymorphism genetic marker of Bacillus cereus.