Enterocin AS-48 was obtained from cultured broths of the
producer strain E. faecalis A-48-32 after concentration by cation
exchange chromatography as described by Abriouel et al. (2003).
Bacteriocin concentrates were desalted through 2000 mw cut-off
dialysis tubing (Sigma) and filtered through 0.22 mm pore size low
protein binding filters (Millex GV; Millipore Corp., Belford, MA,
USA) under sterile conditions. Samples were serially diluted and
tested (100 ml) for bacteriocin activity against the indicator strain
E. faecalis S-47 by the agar well diffusion method using stainless
steel cylinders of 8 mm (outer) diameter (Abriouel et al., 2003). One
arbitrary unit (AU) was defined as the highest dilution producing
a visible (9 mm diameter) zone of inhibition. The bacteriocin
concentration of samples was determined from the previously
reported specific activity value of 3.5 AU/mg protein