Characterization of Bacteriocin produced Lactobacillus bulgaricus acting on bovine mastitis pathogens

The antimicrobial substance produced by Lactobacillus bulgaricus was inactivated by pretense, which confirmed it as a bacteriocin and referred to 'bulgaricin HJ'. The bulgaricin HJ showed the inhibitory activity against mastitis pathogens, gram-positive and gram-negative bacteria. The optimal conditions for the production of bulgaricin HJ were at the temperature of $30^{\circ}C$ and 10 h after cultivation of L. bulgaricus. Staph. and Strep. agalactiae, common bovine mastitis pathogens, were treated with bulgaricin HJ by the agar well diffusion method and showed antimirobial activities to the bovine mastitis pathogens. The activity of the bulgaricin HJ was maintained at pH 6-7 and $100^{\circ}C$ for 60 min against the mastitis pathogens. The bulgaricin HJ was determined as class IV bacteriocin by various enzyme treatments. Colony forming units analysis with indicator strains by the treatments of bulgaricin HJ indicates that the mode of bacteriocin action was bactericidal rather than bacteriostatic.