Novel sucrose transposons from plant strains of Lactococcus lactis

Lactococcus lactis strains isolated from vegetable products transferred the ability to ferment sucrose in conjugation experiments with the recipient s train L. lactis MG1614. Nisin production and sucrose fermentation were tran sferred together from two strains, but transfer also occurred from several other strains which did not produce nisin. Pulsed-field gel electrophoresis analysis showed that all transconjugants had acquired large chromosomal in sertions at two main sites. Nisin-sucrose transconjugants had gained insert s of 70 kb, while those that fermented sucrose without nisin production con tained inserts of between 50 and 110 kb. Transconjugants from one donor had acquired a separate insertion of 55 kb which correlated with enhanced bact eriophage resistance, but contained neither nisin nor sucrose fermentation genes. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.