Antilisterial and amylase-sensitive bacteriocin producing Enterococcus faecium SH01 from Mukeunji,a Korean over-ripened kimchi

A bacteriocinogenic strain identified as Enterococcus faecium SH01 was isolated from mukeunji, a Korean traditional over-ripened kimchi with antimicrobial activities against Listeria monocytogenes KCTC 3569 and Lactobacillus curvatus KFRI 166. The maximum bacteriocin titer (1,280 AU/mL) was detected at the early stationary phase and was maintained for 28 h with no activity loss. The bacteriocin activity, which disappeared after treatment with the proteolytic enzymes α-chymotrypsin, pronase E, proteinase K, and trypsin, was partially inactivated using α-amylase. The activity of bacteriocin SH01 remained after heat treatment (121°C, 15 min) and exposure to pH values from 2–12. The molecular weight of crude bacteriocin SH01 was 3 kDa. The bacteriocin production phenotype (Bac⁺) was linked to a 6 kb plasmid. Bacteriocin SH1 production was not induced by the co-presence of viable cells, heat treatment, or a cell-free indicator supernatant. The mode of action of bacteriocin SH1 was bactericidal.