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

摘要

Leuconostoc sp. J2, isolated from naturally fermented" Kimchi, produced a bacteriocin which was named leuconocin J. This bacteriocin exhibited an inhibitory activity against several lactic acid bacteria and some food- borne pathogens. The antimicrobial substance was secreted into the medium during the late log phase. It appears to be proteinaceous since its activity was completely inactivated by a range of proteolytic enzymes, and it was also relatively heat-stable. The bacteriocin was partially purified by ammonium sulphate precipitation, following dialysis. The apparent molecular mass of partially 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 pUCll8 and transformed into Escherichia coli DH5#alpha#. Phenotypic expression of the bacteriocin production was detected in transformants harbouring pULBJ5.5. Finally, Southern blotting with the 2.3 kb insert as a probe against plasmid digests of Leuconostoc sp. J2 revealed that the cloned foreign DNA originated from Leuconostoc sp. J2.