Screening and estimation of antibacterial activity of bacteriocins produced by Enterococcus faecium LR isolated from raw horse milk samples.

Lactic acid bacteria are microorganisms that can be present in meat, milk and fermented products, as well as fermented drinks and vegetables, and they inhibit the growth of pathogenic and decaying microorganisms. Our aim was isolating, screening, characterization and estimation of bacteriocin/s of Lactic acid bacteria isolated from Horses milk in Jeddah city, Saudi Arabia. That have antagonistic activity against a wide range of pathogenic bacteria. On MRS agar medium 16 LAB isolates were examined using the agar well diffusion method against the pathogenic bacteria (Gram-positive bacteria: S. aureus ATCCBAA977, ST. Pneumonia ATCC49619) and (Gram-negative bacteria: E. coli ATCC35218, P. aeruginosa ATCC27853). The results showed that 12 isolates out of 16 isolates (75%) worked to inhibit all types of pathogenic bacteria used. The best isolate was identified using molecular methods; the results showed that the isolate (H6) matched 100% with (Enterococcus faecium LR135401.1). This isolate produced the highest bacteriocin at 35°C/24 h/pH (6.5).