Whole-cell protein electrophoretic analysis of viridans streptococci: evidence for heterogeneity among Streptococcus mitis biovars

One hundred reference strains representing all species belonging to the different phylogenetic lineages of the viridans streptococci were examined by means of one-dimensional whole-organism protein electrophoresis. For most of the species examined, multiple strains characterized by DNA-DNA hybridization were included and, wherever described, representatives of different biochemical variants were analysed. Most species were clearly differentiated. The data support the viewpoint that members of the Streptococcus anginosus group constitute a single species and indicate that Streptococcus mitis biovar 2 is a heterogeneous taxon comprising strains from several streptococcal species.