Document Type : Research articles


1 Department of Biology Ahar Branch, Islamic Azad University, Ahar, Iran

2 Department of food hygiene, Tabriz Branch, Islamic Azad University, Tabriz, Iran


Background: Lactobacilli are commonly used organisms in the production of probiotics. Objectives: The present study was conducted to examine the effect of probiotics isolated from dairy products on the expression of Stx1 and Stx2 genes in verotoxigenic E. coli (VTEC). Methods: This experimental study was conducted during April and January 2016 in East Azerbaijan, Iran. At first, Hundred samples of traditional dairy products were collected. Then, using standard phenotypic and genotypic methods, the Lactobacillus casei (L. casei) and lactobacillus (L. plantarum) were studied. Subsequently, these strains were examined along with the pathogenic bacteria strain of Escherichia coli (E. coli) (O157: H7) by neighboring cultivation. After extraction of mRNA, the expression of these genes was determined using real- time PCR.
Results: The results revealed that L. casei reduces the expression of Shiga toxin (Stx1 and Stx2) genes more compared to L. plantarum (P = 0.001). Moreover, it was found that both Lactobacilli reduce the expression of Stx1 genes more than Stx2. Conclusions: Probiotics could be used to prevent and control intestinal diseases caused by E. coli