Plasmid Pattern of Group N (lactic) Streptococci

Abstract

The presence of plasmid DNA was demonstrated for all of 51 investigated strains of Streptococcus lactis, S. lactis subsp. diacetylactis, and S. cremoris. The plasmid patterns of representative strains analysed by agarose gel electrophoresis of the DNA are documented. This pattern does not appear to provide a basis for species differentiating. Lactosenegative derivatives having lost some of their plasmids were obtained by curing with nalidixic acid.