Characterisation of a cell-free supernatant obtained from cultures of Enterococcus faecalis DBFIQ E24 with antagonistic activity against bacteria, yeasts and moulds

Enterococcus faecalis DBFIQ E24 strain produces antimicrobial substances that inhibit the growth of food-borne pathogenic bacteria, yeasts and moulds. This broad antimicrobial spectrum was determined by obtaining the cell-free supernatant (CFS) and employing the agar-well-diffusion method. Its antibacterial activity was completely inactivated by the action of proteinase K and not affected by catalase action. Besides, it was stable to thermal treatments, showing maximum antibacterial activity at pH 7.0. Moreover, CFS showed a bactericidal effect against Escherichia coli DBFIQ Ec9 strain. All these interesting physicochemical properties allow that either CFS or E.faecalis DBFIQ E24 strain to be considered as potential food biopreservatives.