Analysis of the high frequency conjugal transfer systems in lactococci

Tukel C., Tuncer Y., Akcelik M.

MILCHWISSENSCHAFT-MILK SCIENCE INTERNATIONAL, vol.60, no.3, pp.262-265, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 60 Issue: 3
  • Publication Date: 2005
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.262-265
  • Süleyman Demirel University Affiliated: No


High frequency conjugal transfer systems were analysed in lactococci using by 5 donor and two recipient strains with different phenotypic characters. High frequency transfer of plasmids was found to be associated with the formation of aggregation structures in donor-recipient strain mixtures in the conjugation experiments. Aggregation abilities of Lactococcus lactis strain mixtures were determined to be controlled with a two element-system one of which was encoded by lactose plasmids (Clu) and the other by chromosomal DNA (Agg). Conjugal transfer frequencies of plasmids were obtained at high levels such as 4.2 x 10(-2)-1.5 x 10(-4) per donor cell when aggregate forming donor-recipient mixtures were used. Plasmid stabilities were determined between 82-98 % in conjugants obtained from conjugation experiments in which L. lactis subsp. lactis MLL40-29 was used as recipient. A reduction in the production of a 48.9 kDa protein was determined with the disappearance of the clumping phenotype.