The Inhibitory Effect of Potassium Sorbate and Bifido-Bacterium on Shiga Toxin Producing E. coli in Kareish Cheese
The Inhibitory Effect of Potassium Sorbate and Bifido-Bacterium on Shiga Toxin Producing E. coli in Kareish Cheese
Gamilat A. Elsaid1, Weam Mohamed Baher1*, Eman Shukry1, Abeer E. Abd El. Ghafar2, Marwa Shalaby1
ABSTRACT
Kareish cheese is considered among the most important dairy products in Egypt. It is of a high nutritive value and supports part of the human needs of protein, vitamins, and minerals. This study aimed at estimation of most probable number (MPN) of coliforms and E. coli and investigation of the prevalence of shiga toxin producing E. coli in kareish cheese collected from grocery stores and street vendors at Mansoura city, Egypt. In addition, molecular confirmation, and detection of shiga toxin coding genes (stx1, and stx2) in the recovered E. coli isolates was done using PCR. Moreover, the inhibitory effects of potassium sorbate (KS) and Bifidobacterium animalis subsp. lactis on the growth of E. coli O26 were screened. The estimated MPN of coliforms and E. coli in kareish cheese collected from grocery stores were 3.44 ± 0.12 and 2.22 ± 0.14. These values were 4.61 ± 0.11 and 3.60 ± 0.25 in samples collected from street vendors. The prevalence rates of E. coli were 20%, and 60% in kareish cheese samples collected from grocery stores and street vendors, respectively. The identified E. coli serotypes were E. coli O2:H6, E. coli O26:H11, E. coli O55:H7, E. coli O78:H-, E. coli O111:H4, and E. coli O119: H. All isolated harbored 16S rRNA specific gene for E. coli. The expression of shiga toxin coding genes indicated that E. coli O2:H6, E. coli O111:H4, and E. coli O119:H harbored only stx2. E. coli O26:H11 and E. coli O55:H7 harbored both stx1, and stx2; however, E. coli O78:H- did not harbor any of the tested genes. The use of potassium sorbate and Bifidobacterium animalis subsp. lactis during kareish cheese manufacture could significantly reduce E. coli O26:H11 in a concentration-dependent manner. Therefore, strict hygienic measures should be adopted during all manufacture steps of kareish cheese. The use of KS and Bifidobacterium animalis subsp. lactis during kareish cheese manufacture is highly recommended.
Keywords | Kareish cheese, E. coli, Egypt, potassium sorbate, Bifido-bacterium
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August 2022
Vol. 10, Iss. 8, Pages 1659-1886
