Prevalence and virulence factor genes of Bacillus cereus isolated from milk and some dairy products

Abstract

Two hundred and fifty samples (Marketable milk, Ras cheese, Domiati cheese and ice cream), were randomly obtained from various dairy shops, supermarkets and ice cream shops in Assiut City, Egypt, during the period of November 2022 to March 2023. These samples were examined for the detection and counting of Bacillus cereus. The positive B. cereus isolates were analyzed by PCR to detect 16s rRNA gene for B. cereus, cytotoxin K (cyt K) and emetic gene (ces). Out of the 250 examined samples, 14 (5.6%) were contaminated by B. cereus. The analyzed ice cream had the highest prevalence (11.53%), followed by Ras cheese samples. The prevalence of ces gene recorded in the examined isolates was 57.14%, while cyt K gene was found in all isolates. Moreover, proteolytic and lipolytic activity investigations revealed that nearly all strains released protease enzyme (92.85%), most of which (64.28%) could produce lipase enzyme.

Keywords

• Bacillus cereus
• Marketable milk,
• Dairy products
• Virulence genes
• Proteolysis
• Lipolysis