The biochemical characterization of the bacteriocine synthesized by Enterococcus faecium VL47 was realized, resulting a high thermal stability, resistance to acid pH, organic solvents and to the used enzymes. The production of antimicrobial peptides (bacteriocines) was used against three bacterial strains, Bacillus cereus CMGB 215, Listeria innocua CMGB 218, Escherichia coli CBAB2. The synthesis of bacteriocines was tested by using the MRS medium, thus, resulting an inhibiting effect against all three sensitive strains, even if the carbon source was replaced by lactose, sucrose, sorbitol, sorbose, arabinose, maltose, galactose and trehalose. The inhibiting effect of the precipitated bacteriocine was obtained when using a concentration of ammonium sulphate, with an average diameter of 1 cm against sensitive strains. To outline the effect of prebiotics on bacteriocine synthesis, MRS was supplemented by 1% inulin from Chichori, inulin from Dahlia, lactulose, raffinose, stachyose, xylose. It resulted that the maximum inhibiting effect was obtained when using lactulose, in a concentration of 1%.