Food Science/Microbiology : Article ; Characterization of the Bacteriocin J4 Produced by Bacillus amyloliquefaciens J4 Isolated from Korean Traditional Fermented Soybean Paste = Food Science/Microbiology : Article ; Characterization of the Bacteriocin J4 Produced by Bacillus amyloliquefaciens J4 Isolated from Korean Traditional Fermented Soybean Paste

다국어 초록 (Multilingual Abstract)

In order to isolate the antibacterial bacteriocin-producing bacteria against Listeria monocytogenes, one of noxious and prevalent food-poisoning bacterium, 117 strains of indigenous ferment bacteria were isolated from Korean traditional fermented soybean paste (Doenjang) in Korea. Among the isolated strains, 4 isolates inhibited the growth of L. monocytogenes. Strain J4, showing the strongest inhibition activity against L. monocytogenes, was identified as a Bacillus amyloliquefaciens by 16S rDNA sequencing. The strain had a broad spectrum of antibacterial activity against various food-borne pathogens such as Micrococcus luteus, Vibrio parahaemolyticus, and Staphylococcus aureus besides L. monocytogenes. The bacteriocin J4 was purified by 60% ammonium sulfate precipitation, carboxymethyl (CM)-Sephadex column chromatography, and Sephadex G-100 gel filtration. The purified bacteriocin J4 was estimated to be 39 kDa molecular weight by tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Bacterocin J4 had antimicrobial activity in a wide pH range (2.0-12.0) and was heat-stable at 80˚C for 20 min, but the activity of bacterocin was inactivated by heating at 100˚C for 15 min. The antimicrobial activity of the bacteriocin J4 was completely abolished by treatment with proteolytic enzymes such as protease (type I and IX), papain, trypsin, proteinase K, and pepsin, but not when treated with α-amylase, α-glucosidase, and β-glucosidase. The encoding gene of the bacteriocin J4 was included in chromosomal DNA, not plasmid. The bacteriocin J4 had a bacteriolytic mechanism, resulting in cell wall degradation of L. monocytogenes.