Partial characterization and cloning of leuconocin J, a bacteriocin produced by Leuconostoc sp. J2 isolated from the Korean fermented vegetable Kimchi

Leuconostoc sp. J2, isolated from naturally fermented Kimchi, produced a ba cteriocin which was named leuconocin J. This bacteriocin exhibited an inhib itory activity against several lactic acid bacteria and some foodborne path ogens. The antimicrobial substance was secreted into the medium during the late log phase. It appears to be proteinaceous since its activity was compl etely inactivated by a range of proteolytic enzymes, and it was also relati vely heat-stable. The bacteriocin was partially purified by ammonium sulpha te precipitation, following dialysis. The apparent molecular mass of partia lly purified bacteriocin, as indicated by activity detection after Tricine- SDS-PAGE, was 2.5-3.5 kDa. Leuconostoc sp. J2 plasmid DNA digested by EcoRI was cloned into pUC118 and transformed into Escherichia coli DH5 alpha. Ph enotypic expression of the bacteriocin production was detected in transform ants harbouring pULBJ5.5. Finally, Southern blotting with the 2.3 lib inser t as a probe against plasmid digests of Leuconostoc sp. J2 revealed that th e cloned foreign DNA originated from Leuconostoc sp. J2.