Identification and Virulence Genes Detection of Bacillus Cereus Food Isolates
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Abstract:
To identify the virulence genes of Bacillus cereus food isolates,a total of 130 food samples were collected in Chengdu city in this study. The isolation of Bacillus cereus strains was performed according to the colony morphology on MYP medium. Then 16S rRNA sequencing analysis and Bacillus cereus housekeeping genes (gyrB, rpoB, VrrA, groEL) were used to identify the isolates. Finally, the virulence genes of Bacillus cereus isolates were detected. The results showed that 23 Bacillus cereus isolates were identified from 130 collected food samples. The isolation rate was 17.7%. Twenty-three Bacillus cereus isolates carried all four housekeeping genes (gyrB, rpoB, VrrA, groEL). The virulence genes detection showed nheB and entFM were found in 16 isolates and the detection rates were relatively high (16/23, 69.6%); the nheA and nheC genes were detected in 14 isolated strains and the detection rates were 60.9%; the hblD gene was detected in 11 isolates and the detection rate was 47.8%; the cytK gene was detected in 10 isolates and the detection rate was 43.5%; the bceT gene was detected in 9 isolates and the detection rate was 39.1%; the hblA and hblC genes were detected in 8 strains and the detection rates were 34.8%; the cer and ces genes were detected in 2 isolated strains, and the detection rates were 8.7%; the hblB and Hly genes were not found in any isolates. This study indicated that the occurrence rates of virulence genesin Bacillus cereus food isolates were relatively high, which had a potential threat to food safety. The regulatory authority should pay attention to Bacillus cereus contamination.
