Comparison of some properties of bacteriocins produced by enterecoccus isolated from clinical and food sources

In this study, the bacteriocin producing properties and the inhibiting effects of the resulting bacteriocins against Listeria monocytogenes of 10 food origin and 10 clinical origin strains of enterococci were determined. In addition, antimicrobial properties of the bacteriocins, at different temperatures and pH values were investigated. Antimicrobial activity of bacteriocins of both the food origin and the clinic origin enterococcus strains was obtained by Kirby-Bauer disk diffusion method.It was determined that 14 of 20 bacteriocins derived from Enterococcus strains, inhibited the growth of Listeria monocytogenes. Effects of different temperatures and pH values on antimicrobial activity of 14 bacteriocins (L13, YS1, AS1, JS1, A1, E5, NS1, 226, 227, 228, V98, V105, V188, V198) that show activity against indicator microorganism were determined. Bacteriocins subjected to different temperature applications. Most of the bacteriocins showed antimicrobial effect at 60, 70, 80, 90 and 110°C for 15 minutes against Listeria monocytogenes. However, bacteriocins of E5 and V198 strains are completely lost their activity when exposed to 110°C for 15 minutes. It was determined that both food and clinical origin bacteriocins lost their inhibitory activity at 121°C for 15 minutes of heat treatment at autoclave conditions. Bacteriocins subjected to different pH applications. Most of the bacteriocins showed inhibitory activity at pH 3, 5, 7, 9 and 11. It was determined that both food and clinical origin bacteriocins showed their best antimicrobial effect in neutral mediums and also it was detected that acidic and basic mediums decreased the activity.