Abstract: Using agar diffusion method, one strain, named B6, with potent and broad-spectrum antimicrobial activity was selected from the 8 strains of lactic acid bacteria (LAB) isolated from traditional yogurt in Xinjiang, China. It was identified as Lactobacillus plantarum by morphological, physiological and biochemical characteristics and 16S rDNA sequence alignment. The cell-free fermented broth of B6 retained its antibacterial activity after sequential removal of acids and hydrogen peroxide, which indicated that L. plantarum B6 could produce bacteriocin. Polymerase chain reaction (PCR) analysis was carried out to identify the bacteriocin genes of B6 by using 10 pairs of primers designed to be specific for the genes related to the biosynthesis of bacteriocin with the total DNA of strain B6 as the template. The results showed that strain B6 had the structural genes plnE/F/J/K for class IIb bacteriocin. The plnJ gene shared 99% similarity with that of L. plantarum C11 with only one amino acid mutation in the leader peptide region, and the plnE/F/K genes shared 100% similarity with those of L. plantarum C11, which indicated that L. plantarum B6 produced class IIb bacteriocin.

Key words: lactic acid bacteria, screening, antimicrobial effect, bacteriocin, polymerase chain reaction, gene analysis