Investigation of toxigenic Bacillus cereus isolated from raw and cooked rice in Sulaimani city, KRG.

Authors

  • Rezhin Sidiq College of Agricultural Engineering Science, University of Sulaimaini, Kurdistan Region, Iraq Author
  • Huner Arif College of Agricultural Engineering Science, University of Sulaimaini, Kurdistan Region, Iraq Author

Keywords:

Bacillus cereus, raw and cooked rice, toxic genes, colony PCR

Abstract

Bacillus cereus was isolated and investigated within 100 collected samples from raw and cooked rice in Sulaimani city. Twenty-nine out of these samples were found to be contaminated with this bacterium, the highest contamination rate occurred in raw samples 60% (24/40), followed by cooked rice 8.3% (5/60).  B.cereus densities in raw rice samples was 48.7 ×104  CFU g−1, while in the cooked rice exceeded 103 CFU g−1. Identification of the twenty-two strains of the B. cereus was done by VITEK 2 BCL, with probability between 85%-89% which is a good and acceptable level. Then identification of this bacteria at the molecular level was done by colony PCR using primers targeting 16S rRNA gene, diarrheal toxin including non-hemolytic enterotoxin (nheA, nheC and nheD), hemolytic enterotoxin (hblA, hblC, hblD), Cytotoxin K (cytK), bceT and entFM enterotoxin, in addition to the emetic toxin gene (detected by colony PCR). Out of the 22 positive samples, entFM gene was the more abundant (95.4%.) followed by cytK gene which was 77.2% and the percentage of   nheA, nheB, and nheC genes were 63.6, 13.6 and 40.9% respectively, and for hblA, hblC, hblD genes were 31.8, 22.7 and 31.8% respectively. The less percentage of these genes in these isolates was bceT (13.6). The detection of strains with the emetic toxin in raw and cooked rice was negative.

 

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Published

2023-03-05