Magnetic nanoparticles for selective capture and purification of an antimicrobial peptide secreted by food-grade lactic acid bacteria

Abstract

Biocompatible iron oxide nanoparticles (IONPs) were utilized for charge-based selective capture of the cationic bacteriocin pediocin secreted by food-grade lactic acid bacteria (LAB), resulting in the generation of a nanocomposite, which could be readily separated from other secreted metabolites. Interestingly, pediocin activity was conserved and a membrane-directed antibacterial activity typically associated with pediocin was manifested in the nanocomposite. Efficient sequestration of pediocin was also achieved through facile magnetic separation of IONP–pediocin composites and following desorption at pH 2.0, the recovered IONPs could be recycled for a subsequent round of pediocin adsorption. The steady state adsorption isotherm of pediocin with IONPs followed a Langmuir isotherm model. Following the reversible adsorption–desorption process with IONPs, 16-fold purification of pediocin could be achieved. The HPLC profile of the desorbed pediocin revealed a similar retention time to pediocin purified by an established cell-adsorption method and the HPLC eluted fraction also displayed the signature membrane-directed pediocin activity. The facile capture of pediocin, magnetic separation and the possibility of salvaging IONPs for reuse, accompanied by high retention of pediocin activity during the purification process, enhance the merit of IONPs as robust and effective purification tools for a potentially therapeutic antimicrobial peptide.