Inhibitory effect of native enterococci isolates on some of the foodborne bacterial pathogens

Abstract

Enterococci are among lactic acid bacteria that are homogeneous and are commonly found in raw milk and its products. The purpose of this study was to isolate Enterococcus species from raw milk and traditional milk products in Tabriz region and to study their inhibitory effect on some of pathogenic bacteria. For this, 105 specimens including 15 samples of each of raw milk, yogurt, cheese, cream, butter, dough, and whey were tested. After isolation and differential identification of the species, 24 isolates were selected based on the sample type and the variety of Enterococcus species. Due to the pathogenic potential of E. faecalis and E. fascism species, they were evaluated for the presence of Esp and Asa1 genes, respectively. The inhibitory effect of Enterococcus isolates was tested on nine important foodborne pathogens using overlay method. According to the results, nine species of E. fascism, E. faecalis, E. gallinarum, E. avium, E. Benedetti, E. caseliflavus, E. hirae, E. saccharoliticus and E. raffinosus were isolated. All isolates had an inhibitory effect on indicator organisms; however, the inhibitory effect was found different among various species and various strains. E. faecalis and E. fascism species had the most antibacterial effects. The molecular evaluation showed that out of 5 isolates of E. faecalis, 2 isolates contained Esp gene. In the case of E. faecalis, none of the isolates harbored Asa1 gene. If further experiments are carried out in relation to the proven safety of enterococci, their inhibitory effect on food pathogenic bacteria can be used.

Keywords

• Enterococcus
• raw milk
• Traditional products
• Antagonistic effect
• Dual layer method