Identification and partial characterization of lacticin BH5, a bacteriocinproduced by Lactococcus lactis BH5 isolated from Kimchi

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer that has bactericidal activity against Micrococcus fl avus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lacti s by API test. Lactococcus lactis BH5 showed a broad spectrum of activity a gainst most of the nonpathogenic and pathogenic microorganisms tested by th e modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by L. lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and de creased after the late stationary phase. Lacticin BH5 also showed a relativ ely broad spectrum of activity against nonpathogenic and pathogenic microor ganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely destroyed by protease XIV. The in hibitory activities of lacticin BH5 were detected during treatments up to 1 00 degreesC for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. It demonstra ted a typical bactericidal mode of inhibition against M. flavus ATCC 10240. The apparent molecular mass of lacticin BH5 was estimated to be in the reg ion of 3 to 3.5 kDa, by the direct detection of bactericidal activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.