Expression of a novel bacteriocin—the plantaricin Pln1—in Escherichia coli and its functional analysis

Abstract

A potential bacteriocin gene was isolated from 18575 ORFs by bioinformatics methods. It was named pln1, and cloned into pET32a. Then, it was expressed as a thioredoxin-Pln1 fusion protein in Escherichia coli BL21 (DE3). The fusion protein was purified by Ni-NTA, and thioredoxin was removed by enterokinase. Finally, Pln1 was purified using a cation affinity column. The yields of fused and cleaved Pln1 peptides were 100–110 mg/l and 9–11 mg/l, respectively. Pln1 was stable in an acidic environment and at temperatures below 60 °C, but was easily degraded under alkaline conditions and by protease treatment. The cleaved and purified Pln1 showed strong antimicrobial activity against gram-positive bacteria such as Micrococcus luteus CMCC 63202, Staphylococcus epidermidis, Lactococcus lactis NZ3900, Lactobacillus paracasei CICC 20241, and Listeria innocua CICC 10417. In particular, Pln1 had a better activity against methicillin-resistant S. epidermidis (MRSE) than nisin, thereby offering an attractive approach to counter bacterial antibiotic resistance.