Abstract
Streptococcus ferus was originally isolated from rats and, although it is often considered a member of the 'mutans group' streptococci on the basis of phenotypic criteria, its phylogenetic position has not been investigated. Here, the relationship of this organism to other streptococcal groups has been determined by DNA--DNA hybridization and by partial sequencing of 16S rDNA and the sodA gene. S. ferus was found to be distantly related to all currently described streptococci, with no strong evidence in support of its inclusion within any of the currently recognized streptococcal groups.