ISOLATION, BIOCHEMICAL AND MOLECULAR HARACTERIZATION OF LACTOBACILLUS ISOLATED FROM BEEF AND EVALUATING THEIR ANTIBACTERIALEFFECTS ON LISTERIA MONOCYTOGENES

Increasing consumption of ready to eat foods which usually receive low heating process can cause the emergence of microbial hazards. Listeria monocytogenes is one of the most dangerous foodborne bacteria which can result in disease and death in old, pregnant and immunosuppressed individuals. Lactobacilli are naturally present in most foods. Since ancient times, they were regarded as natural preservatives in food. The aim of this study was to evaluate the biochemical and molecular characterization of Lactobacillus isolates and investigate their antibacterial effects on Listeria monocytogenes
Sixty five meat samples were obtained from slaughter house in Urmia city. First, isolated bacteria were evaluated using phenotypic methods (morphology, Gram stain and catalase test). Then, polymerase chain reaction (PCR) and sugar fermentation tests were used. Finally, their antibacterial properties against Listeria monocytogenes were tested by two methods (agar wells diffusion and spot on plate).
Six strains of lactobacilli were identified using PCR. The antibacterial tests showed moderate effects of lactobacilli on Listeria monocytogenes growth.
The results indicated that lacobacilli can be used as a biocontrol agent to inhibit of Listeria monocytogenes growth.