Journal: |
Zagazig Veterinary Journal
Zagazig University
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Abstract: |
Kariesh cheese, ice cream, and pasteurized milk are among the popular dairy
products with high nutritive values. These products are commonly consumed in Egypt at
all ages. However, the surrounding surfaces and equipment might lead to contamination of
such dairies with foodborne pathogens such as Bacillus cereus. Microbial biofilm
production is a developed mechanism that enhances survival and resistance to harsh
environment along with spores. This study aimed to investigate the prevalence of B. cereus
in dairy products including kariesh cheese, ice cream as well as pasteurized milk, dairy
plant surfaces, and equipment. Besides, the ability of the identified B. cereus isolates to
produce biofilm were further examined. In a prevention trial, Nigella sativa and olive oils’
nanoemulsions were used at a concentration of 1%, and 2% to reduce B. cereus biofilm
formation. The obtained results revealed isolation of B. cereus from the examined kariesh
cheese, ice cream, pasteurized milk, dairy plant surfaces, and equipment at 44%, 16%, 8%,
72%, and 68%, respectively, with average counts of 3.69 ± 0.23, 2.58 ± 0.19, 2.15 ± 0.21,
5.36 ± 0.39, and 4.46 ± 0.59 log 10 cfu/g, respectively. Molecular confirmation of the
recovered B. cereus isolates revealed that all isolates harbored B. cereus -specific 16S
rRNA, and Cal Y, biofilm-matrix protein. All B. cereus isolates had the ability to produce
biofilm. Nigella sativa, and olive oils’ nanoemulsions reduced B. cereus-produced biofilm
in a concentration-dependent manner.
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