ENTEROCIN-B, A NEW BACTERIOCIN FROM ENTEROCOCCUS-FAECIUM T136 WHICH CAN ACT SYNERGISTICALLY WITH ENTEROCIN-A

The strain Enterococcus faecium T136 produces two bacteriocins, entero cin A, a member of the pediocin family of baderiocins, and a new bacte riocin termed enterocin B. The N-terminal amino acid sequences of ente rocins A and B were determined, and the gene encoding enterocin B was sequenced. The primary translation product was a 71 aa peptide contain ing a leader peptide of the double-glycine type which is cleaved off t o give mature enterocin B of 53 as. Enterocin B does not belong to the pediocin family of bacteriocins and shows strong homology to carnobac teriocin A. However, sequence similarities in their leader peptides an d C-termini suggest that enterocin B and carnobacteriocin A are relate d to bacteriocins of the pediocin family. Enterocins A and B had only slightly different inhibitory spectra, and both were active against a wide range of Gram-positive bacteria, Including listeriae, staphylococ ci and most lactic acid bacteria tested. Both had bactericidal activit ies, but survival at a frequency of 10(-4)10(-2) was observed when sen sitive cultures were exposed to either bacteriocin. The number of surv ivors was drastically reduced when a mixture of the two baderiocins wa s added to the cells.