Construction of Streptococcus lactis subsp. lactis Strains with a Single Plasmid Associated with Mucoid Phenotype

摘要

Lactose-fermenting mucoid (Lac+ Muc+) variants of plasmid-free Streptococcus lactis subsp. lactis MG1614 were obtained by protoplast transformation with total plasmid DNA from Muc+S. lactis subsp. cremoris ARH87. By using plasmid DNA from these variants for further transformations followed by novobiocininduced plasmid curing, Lac? Muc+ MG1614 strains containing only a single 30-megadalton plasmid could be constructed. This plasmid, designated pVS5, appeared to be associated with the Muc+ phenotype.