In particular, the analysis of E. faecium SM21 antimicrobial peptides by Tricine-SDS-PAGE, and further antimicrobial assays against L. monocyto genes 99/287, showed a broad band with a molecular weight of approximately 6.0–7.5 kDa (Figure5A). The analyses of different structural enterocin genes in the DNA of E. faecium SM21 by PCR reactions was also done and revealed that the entA, B and P genes were amplified (Figure 4B). The size of the fragments of entA (126bp) and ent B (168 bp) were identical to those obtained for E. faecium CRL1385, the strain used as the positive control. The specific PCR fragment of 120 bp, corresponding to the entP gene,was also amplified. Moreover, no specific PCR fragments were detected with the set of primers for bacteriocins L50A/Band 31 (Figure 5B).