INHIBITION OF STAPHYLOCOCCUS AUREUS IN BUFFER, CULTURE MEDIA AND FOODS BY LACIDIN A, A BACTERIOCIN PRODUCED BY LACTOBACILLUS ACIDOPHILUS OSU133

Thirty seven strains of lactobacilli and leuconostocs were screened for bacteriocin production. A bacteriocin-like substance (designated lacidin A) was detected in culture filtrate of Lactobacillus acidophilus OSU133. Lacidin A inhibited Enterococcus faecalis, L. acidophilus, Lactobacillus delbrueckii subsp. lactis, and Staphylococcus aureus. The bacteriocinogenic nature of lacidin A was confirmed by eliminating the inhibitory effects of acid, hydrogen peroxide and phage and by loss of activity upon hydrolysis with proteolytic enzymes. The bacteriocin is relatively heat-stable and has considerable bactericidal action against S. aureus in phosphate buffer. Lacidin A also demonstrated bacteriostatic action against S. aureus in brain heart infusion and heat-treated milk and liquid whole egg.