Identification and Characterization of a Bacteriocin from the Newly Isolated HD15 with Inhibitory Effects against .

Natural antimicrobial substances are needed as alternatives to synthetic antimicrobials to protect against foodborne pathogens. In this study, a bacteriocin-producing bacterium, HD15, was isolated from doenjang, a traditional Korean fermented soybean paste. We sequenced the complete genome of HD15. This genome size was 4,173,431 bp with a G + C content of of 43.58%, 4,305 genes, and 4,222 protein-coding genes with predicted functions, including a subtilosin A gene cluster. The bacteriocin was purified by ammonium sulfate precipitation, Diethylaminoethanol-Sepharose chromatography, and Sephacryl gel filtration, with 12.4-fold purification and 26.2% yield, respectively. The purified protein had a molecular weight of 3.6 kDa. The N-terminal amino acid sequence showed the highest similarity to 168 subtilosin A (78%) but only 68% similarity to subtilosin proteins, indicating that the antimicrobial substance isolated from HD15 is a novel bacteriocin related to subtilosin A. The purified protein from HD15 exhibited high antimicrobial activity against and . It showed stable activity in the range 0-70°C and pH 2-10 and was completely inhibited by protease, proteinase K, and pronase E treatment, suggesting that it is a proteinaceous substance. These findings support the potential industrial applications of the novel bacteriocin purified from HD15.