Characterization of enterocin 1146, a bacteriocin from Enterococcus faecium inhibitory to Listeria monocytogenes

Enterococcus faecium DPC 1146 produces a bacteriocin, enterocin 1146, which is inhibitory to Listeria monocytogenes. Enterocin 1146 was produced in GM17 and in milk. The bacteriocin was partially purified by ammonium sulfate precipitation. Its molecular weight, estimated by SDS-PAGE, was 3.0 kDa. It could be stored at -20°C without loss of activity, but pH had a marked effect on enterocin 1146, which was more stable at both high (up to 120°C) and low temperatures (4°C) at pH 5 than at pH 7 and 9. The sensitivity of 57 strains belonging to 35 different species was studied using a critical dilution assay. L. monocytogenes and L. innocua were most sensitive; enterocin 1146 had a bactericidal effect on Listeria. Starter and nonstarter lactic acid bacteria (except Lactobacillus sake) were insensitive or relatively resistant to the bacteriocin. Genetic determinants for bacteriocin production and immunity do not appear to be plasmid borne.