Detection and preliminary characterization of a bacteriocin (plantaricin 35d) produced by a Lactobacillus plantarum strain

Lactic acid bacteria (134) from Italian sausages were tested for the production of antimicrobial substances (bacteriocins). Six percent of these showed antibacterial activity against one or several closely related microorganisms used as indicators. Lactobacillus plantarum 35d in particular produced a bacteriocin of high activity (320 AU ml−1) and a wide range of antimicrobial activity including S. aureus, L. monocytogenes, and A. hydrophila. The bacteriocin withstood heating at 80°C for 120 min and storage at 4°C for 6 months. The mode of action was identified as bactericidal. The apparent molecular weight of the bacteriocin extracted with n-butanol was estimated to be 4.5 kDa.