Partial characteristics and antimicrobial mode of pediocin produced by Pediococcus acidilactici PA003

Abstract

Pediocin was found to have an effective antimicrobial function against Listeria monocytogenes and some other Gram-positive bacteria produced by Pediococcus acidilactici PA003, which remained active between pH 2.0 and 12.0 after a 2 h treatment, at 4 °C and −20 °C for 1 month and at 40, 60, 80, 100, and 121 °C for 1 h. Furthermore, complete inactivation or significant reduction of antimicrobial activity was observed after treatment of the cell-free supernatant with proteinase K, pepsin, trypsin, and papain. According to the study on the correlation between pediocin protein secondary structure and antimicrobial activity by circular dichroism spectra analysis, as pediocin α-helix levels increased, β-strand and β-turn content decreased, and the pediocin activity decreased thereupon. Analysis of pediocin adsorption characteristics indicated that the adsorption effect of pediocin was not affected by temperature and duration, but pH was a crucial factor. In general, 98 % of the pediocin was adsorbed at pH values near 6.0, and the lowest adsorption took place at pH levels below 2.0 or above 10.0. By testing the ultraviolet absorption material and by determining the pH gradient and the membrane potential gradient, we determined that the occurrence of holes on the sensitive bacteria cell membrane, the dissolution of intracellular nucleic acid and protein material, and the dissipation of proton motive force led to sensitive bacteria cell death after treatment with pediocin.