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A lactic acid bacterium, strain KCA238-6, was isolated from traditionally fermented white kimchi. It produced bacteriocin which was active against not only other lactic acid bacteria but also a wide range of food pathogens. Based upon the cell morphology, carbohydrate fermentation profile and enzymatical assays, this strain was identified as Lactococcus lactic and named as Lactococcus lactic KCA2386. Bacteriocin production by L. lactic KCA2386 was maximized at the initial pH of 7.0 and at 37℃ in MRS broth. The bacteriocin was purified by canon exchange chromatography (CM-cellulose) and gel filtration (Sephadex G-50). The apparent molecular weight of the partially purified bacteriocin was calibrated as approximately 8,100 dalton on the sodium dodecyl sulfate polyacrylamide gel electrophoresis. The bacteriocin was neither inactivated by lysozyme, β-amylase, lipase and RNase A nor by some of the selected organic solvents. It was also heat stable and exhibited bactericidal mode of inhibition against Lactobacills delbrueckii-lactic ATCC4797. Based upon these experimental data, the bacteriocin was named as lactococcin K2386. L. lactis KCA2386 exhibited one residential plasmid of 56.4 kb in molecular size. Plasmid-cured mutant still produced lactococcin K, confirming that lactococcin production in L. lactic KCA2386 appeared to be mediated by the chromosome.
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