To isolate bacteriocin-producing lactic acid bacteria (LAB) that inhibit Lactobacillus plantarum, which can induce kimchi spoilage, a strain of L. plantarum was first isolated from kimchi and used as an indicator. The isolate was identified as L.
plan...
To isolate bacteriocin-producing lactic acid bacteria (LAB) that inhibit Lactobacillus plantarum, which can induce kimchi spoilage, a strain of L. plantarum was first isolated from kimchi and used as an indicator. The isolate was identified as L.
plantarum through 16S rRNA sequencing and recA multiplex PCR analysis and was named L. plantarum JP0059. An LAB strain that inhibits JP0059 was isolated from kimchi, identified as Lactobacillus brevis through 16S rRNA sequencing, and named L. brevis JP0063. Lactobacillus brevis JP0063 showed maximum production of bacteriocin in the exponential and stationary phases. This bacteriocin primarily inhibited homolactic fermentable Lactobacillus, but not Leuconostc. The bacteriocins were partially purified from the culture supernatant using a cation-exchange column. SDS-PAGE confirmed that the partially purified bacteriocin had a molecular weight of approximately 5 kDa and was relatively stable under pH and heat treatment.
However, the bacteriocin activity disappeared after proteinase K treatment. Bacteriocins produced by JP0063 inhibited JP0059 through bactericidal action. The N-terminal amino acid sequence of the bacteriocin was analyzed as KKKKKVACTWGNAAAA, which was highly homologous to that of brevicin 925A-γ produced by L. brevis 925A. Primers were designed based on the brevicin 925A-γ neighboring genes, and PCR amplification and sequencing was performed; two bacteriocin genes were found. The amino acid sequences deduced from the bacteriocin genes were compared with those of brevicin 925A. In the breB gene, a single amino acid in the signal peptide varied, whereas in breC gene, three amino acids in the bacteriocin structural gene varied.