STUDY ON ANTAGONIST ACTIVITY OF LACTOBACILLI ISOLATED FROM BUFFALO MILK AND YOGHURT AGAINST SOME BACTERIAL PATHOGENS

Background and Aim:To overcome the increasing incidence of bacterial infections in humans as well as the rising resistance of pathogens to available antibiotics, there is a need for biological agents to control microbial pathogens. Considering that there has been no research on the antagonistic activity of Lactobacilli isolated from buffalo milk and yoghurt against some important pathogenic bacteria in Golestan province, the aim of this study was to evaluate their antagonistic activity against 9 of them.Methods:Samples were collected from west of Golestan province (suburbs of Bandar Gaz) under sterile conditions. The samples were cultured in MRS media and incubated under anaerobic conditions for 48 hours at 37°C. After purification, the isolates were identified by Gram staining, catalase and oxidase tests, and fermentation pattern of carbohydrates. Then, their antimicrobial effects were evaluated against the studied pathogenic bacteria. For this purpose, the well diffusion method was used. After 24 hours of incubation at 37°C, the inhibitory zone around the wells was measured.Results:Six strains belonging to lactic acid bacteria including Lactobacillus plantarum, Lactobacillus casei and Lactobacillus Composti were isolated. L. Casei had the highest inhibitory effect on Klebsiella pneumonia. L. Plantarum had the most antagonistic activity against Staphylococcus aureus and Shigella flexneri. L. Composti had a similar inhibitory effect on S. aureus, S. Flexeneri and Salmonella typhimurium.Conclusion:: Based on the result, lactobacilli isolated from the buffalo milk and yogurt samples showed a variable range of antagonistic activity against pathogens studied in this research.

کلیدواژه ها:

Antagonistic ، Buffalo ، Lactobacilli ، pathogens