Conjugative transfer of ra⁄nose metabolism in Lactococcus lactis

Lactococcus lactis subsp. lactis strains isolated from various sprouted seed products were able to transfer the ability to ferment raffinose in conjugation experiments at frequencies between 1034 and 1037 per donor cell. There was no evidence of plasmid transfer, but pulsed-field gel electrophoresis analysis showed that all transconjugants had acquired large chromosomal insertions indicative of conjugative transposons. Raffinose transconjugants contained inserts of 45 or 60 kb at one of two chromosomal sites, and these inserts contained two copies of an element related to the lactococcal insertion sequenc