Isolation of bacteriocins through expanded bed adsorption using a hydrophobic interaction medium

Two lactic acid bacterium bacteriocins were isolated from fermentation medium through expanded bed adsorption using a hydrophobic interaction gel. First, amylovorin L471, produced by Lactobacillus amylovorus DCE 471, was selected for the optimisation of the loading and eluting conditions. Secondly, the results of the optimisation were applied for the isolation of enterocin RZS C5, a bacteriocin produced by Enterococcus faecium RZS C5. Optimal adsorption was obtained for a medium with concentration of 1.0 M ammonium sulphate and adjusted to pH 4.0 (94.9% for amylovorin L471 and 75.0% for enterocin RZS C5). Elution with 50% ethanol, buffered at pH 6.0, resulted in an optimal total recovery of the bacteriocin activity of 47.6 and 57.6%, respectively. The highest fold purification expressed as the increase in specific activity (AU/mg) corresponded to the highest recovery, being 140- and 1677-fold, respectively. Nevertheless, a total recovery of only 25.6% with an increase of the specific activity of 121 times was obtained after conventional isolation by ammonium sulphate precipitation.