Molecular characterization of Escherichia coli isolated from cheese and biocontrol of Shiga toxigenic E. coli with essential oils

Abstract

The current research was carried out to study the incidence of Escherichia coli (E. coli) in Egyptian cheese (Kariesh and Ras) and molecular characterization of certain E. coli virulence genes (stx1, stx2, eaeA, hlyA and fimH) using multiplex PCR technique. Biocontrol of E. coli with essential oils (clove and thyme oil) was also studied. A total of 150 random samples of Kariesh and Ras cheese (75 each) were collected from various areas in Governorate of Menoufia. According to our results, the frequency of E. coli isolated from Kariesh and Ras cheese was 16% and 5.3%, respectively. Serological identification classified the E. coli strains into two groups, enterohemorrhagic E. coli (EHEC) serogroup (O26: H11, O91: H21, O111: H2 and O103: H2). While the enterotoxigenic E. coli (ETEC) serogroup were detected as O125: H21 which is the most prevalent strain. O171: H2, O86 and O119: H6 belonging to enteropathogenic E. coli (EPEC). The most prevalent gene detected in E. coli strains was stx1 (87.5%) followed by stx2 (86%), fimH (75%), hlyA (50%) and eaeA (25%) genes. Concerning the antimicrobial activity with essential oils, thyme oil (1%) is considered as the bactericidal effect against E. coli (ATCC35150) with improved the sensory evaluation than clove oil (1%). In conclusion, Kariesh and Ras cheese are extremely tainted with pathogenic E. coli strains, which represent a strong hazard on the human health.

Keywords

• Escherichia coli
• Cheese
• Virulence genes
• Biocontrol
• Essential oils