Relatedness among Clusters of Native Food Isolates of Bacillus cereus Based on Isolation Sources and Potent Toxigenic Traits

Genetic relatedness among 12 native isolates of Bacillus cereus obtained from a diversified range of food products including traditional fast foods were evaluated using 4 selected arbitrary primers in RAPD-PCR. The total amplified products of the 4 primers were 168 of 100-1000 bp. The genetic similarity coefficient for these isolates ranged from 0.040 to 0.470. The data analysis generated a dendogram with 3 clusters covering 11 isolates and the remaining one isolate was of non-cluster type. The cluster patterns could distinguish the isolates of B. cereus based on source of isolation, growth temperature and prevalence of toxigenic traits like haemolysin and sphingomyelinase, besides phosphatidylinositol. The present study clearly envisages the usefulness of RAPD as a molecular based analytical tool to understand the relationship between toxigenicity and source of isolation of native isolates of B. cereus occurring as opportunistic pathogen in a wide range of foods.