Abstract: In order to obtain the high-yield two-peptide bacteriocin plantaricin JK, pln J and pln K were successfully heterologously expressed in Escherichia coli BL21 (DE3), and were induced by IPTG. Then the two peptides were expressed as His₆-tag fusion proteins and were separated by Ni²⁺ chelating affinity chromatography. The fusion proteins were cleaved by enterokinase and further purified. The yields of pln J and pln K were around 2-3 and 5-8 mg·L^-1. The antibacterial activity of the peptides against 4 indicator strains, i.e. Staphylococcus citreus, Escherichia coli, Micrococcus luteus, Listeria monocytogenes, was analyzed by agar diffusion method. It was shown that pln J and pln K both could inhibit the growth of the 4 indicator strains, but plantaricin JK had larger inhibition zone than pln J or pln K alone.

Key words: plantaricin JK, heterologous expression, expression and purification, antibacterial activity