DNA-DNA Hybridization Studies and Phenotypic Characteristics of Strains within the 'Streptococcus milleri Group'

Abstract

Twenty-five strains resembling ''Streptococcus milleri'' were compared by DNA-DNA hybridization, by whole-cell-derived polypeptide patterns on SDS-PAGE, and by biochemical tests. Four homology groups were revealed by DNA-DNA hybridization. DNA homology groups 1, 2 and 3 were closely related and contained the type strains NCDO 2226 (Streptococcus constellatus), NCDO 2227 (Streptococcus intermedius) and NCTC 10713 (Streptococcus anginosus), respectively. DNA homology group 4 consisted of four strains received as variants of Streptococcus intermedius which were found not to be closely related to strains in groups 1-3. The data from SDS-PAGE polypeptide patterns and biochemical tests supported the recognition of three centres of variation within the ''Streptococcus milleri group'' corresponding to DNA homology groups 1-3 and indicated that strains of DNA homology group 4 are members of an as yet undescribed species within the virdans streptococci.