Conjugal Transfer and Stability of the Plasmids Determining Exopolysaccharide Production in Lactococcus lactis Strains

Authors: ELA KOÇER, ÇAĞLA TÜKEL, MUSTAFA AKÇELİK

Abstract: A 27.2 kb plasmid in Lactococcus lactis subsp. lactis ELL23, a 32.7 kb plasmid in L. lactis subsp. cremoris ELC5 and a 31.1 kb plasmid in L. lactis subsp. cremoris ELC19 were found to determine exopolysaccharide production (Eps^+) and lactose fermentation (Lac^+) abilities at the end of conjugal transfer studies. Conjugal transfer frequencies (per donor cell) and stability rates of Lac^+/Eps^+ plasmids were determined as 1.0 x 10^{-2 }- 2.8 x 10^{-3} and 80-96%, respectively, after conjugal matings between the aggregative (Agg^+) wild type strains and Agg^+ recipient strain L. lactis subsp. lactis LLT40. On the other hand, conjugal transfer frequencies and stability rates of Lac^+/Eps^+ plasmids occurred as 1.5 x 10^{-3} - 4.5 x 10^{-4} and 65-80%, respectively, after conjugal matings between the same donor strains and non-aggregative (Agg^-) recipient strain L. lactis subsp. lactis ELL42-6.

Keywords: Exopolysaccharide, conjugation, plasmid, Lactococcus lactis

Full Text: PDF