Screening of Bacteriocin-producing Enterococcus faecalis Strains for Antagonistic Activities against Clostridium perfringens

This study was conducted to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens (C. perfringens) from domestic animals to determine their usefulness as probiotics. Bacteriocin-producing bacteria were iso-lated from pig feces by the spot-on-lawn method. A total of 1,370 bacterial stains were isolated, and six were tentativelyselected after identifying the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269 and KCTC5100. The selected strains were identified as Enterococcus faecalis (E. faecalis) by 16s rRNA sequencing. Most of the iso-lated bacterial strains were resistant to 0.5% bile salts for 48 h and remained viable after 2 h at pH 3.0. Some E. faecalis alsoshowed strong inhibitory activity against Listeria monocytogenes KCTC 3569, KCTC 3586 and KCTC 3710. In the presentstudy, we finally selected E. faecalis AP 216 and AP 45 strain based on probiotic selection criteria such as antimicrobialactivity against C. perfringens and tolerance to acid and bile salts. The bacteriocins of E. faecalis AP 216 and AP 45 strainswere highly thermostable, showing anticlostridial activities even after incubation at 121°C for 15 min. These bacteriocin-producing bacteria and/or bacteriocins could be used in feed manufacturing as probiotics as an alternative to antibiotics inthe livestock industry.