Antimicrobial activity of nisin and hen lysozyme

Abstract

Varying concentrations of the food preservatives nisin and lysozyme were adsorbed onto glass surfaces chemically modified to exhibit different degrees of hydrophobicity. The antimicrobial activity of the adsorbed preservatives was evaluated by documenting the ability of Listeria monocytogenes to adhere and grow on the glass surfaces. A bioluminescence protocol was developed to effectively enumerate bacterial cells adhered to glass. Lysozyme adsorption onto glass surfaces was monitored by labeling with ¹²⁵I. Results indicated that synergy was present for 0.9/0.1 molecular ratio of nisin/lysozyme. Synergistic effect was increasing gradually with the increase of nisin in the ratios tested. This trend was observed on both surface types. However, the magnitude of synergy was more pronounced on hydrophobic surfaces than on hydrophilic ones. Results from protein radiolabeling showed that lysozyme was adsorbed with higher mass to hydrophilic surfaces than to hydrophobic ones.