Characteristics and identification of enterocins produced by Enterococcus faecium JCM 5804T

Aims: To screen bacteriocin-producing lactic acid bacteria (LAB) in 52 type and reference strains, which have not previously been studied, with respect to bacteriocins, and to characterize the presence of bacteriocins. Methods and Results: Only Enterococcus faecium JCM 5804(T) showed bacteriocin-like activity. It inhibited the growth of Lactobacillus spp., Enterococcus spp., Clostridium spp., Listeria monocytogenes, and vancomycin resistant Enterococcus (VRE). However, it was not effective against Gram-negative strains, Weisella spp., Leuconostoc spp., Lactococcus spp., or methicillin resistant Staphylococcus aureus (MRSA). The inhibitory activity of Ent. faecium JCM 5804(T) was inactivated by proteinase K, trypsin, alpha-chymotrypsin, and papain, but not by lysozyme, lipase, catalase, or beta-glucosidase. The inhibitory activity was stable at 100degreesC for 30 min, and had a pH range from 2 to 10. The molecular weight of the partially purified bacteriocin(s) was approx. 4.5 kDa, according to tricine-sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Polymerase chain reaction and direct sequencing methods identified three different types of bacteriocins produced by Ent. faecium JCM 5804(T), enterocin A, enterocin B, and enterocin P-like bacteriocin. Conclusion: Enterococcus faecium JCM 5804(T) produced three different types of bacteriocins, and they inhibited LAB and pathogens. Significance and Impact of Study: This is the first report of enterocin A, enterocin B, and enterocin P-like bacteriocin, detected in Ent. faecium JCM 5804(T) among LAB type and reference strains.