Investigation of Antagonistic Effects of Isolated Lactic Acid Bacteria from Different Cheeses of Gorgan City against Main Intestinal Pathogenic Bacteria

Lactic Acid Bacteria (LAB) have been shown to elicit positive health effects particularly in humans. Competitive exclusion of pathogens is one of the most important beneficial health claims of probiotic bacteria. This study was conducted with the aim of isolation of Lactic Acid Bacteria from different Cheeses and their effects on the main pathogenic bacteria in intestine which might provide important information regarding its probiotic potential and its utilization in the future. Morphological, cultural and biochemical characteristics were employed to identify lactic acid bacteria, isolated from different Cheeses in different areas in Gorgan city, Iran. From 9 traditional Cheese and 2 industrial Cheese samples a total of 38 isolates were isolated, 36 isolates from local Cheese and 2 isolates from industrial Cheese. The results showed that Lactobacillus casei has the highest frequency. Also this species showed antagonistic activity against pathogens including Escherichia coli, Staphylococcus aureus, Bacillus cereus and Citrobacter freundii, with an inhibition zone diameter of 17 mm.