Taxonomic Studies on Streptococcus bovis and Streptococcus equinus: Description of Streptococcus alactolyticus sp. nov. and Streptococcus saccharolyticus sp. nov.

Genetical and biochemical studies were performed on strains of Streptococcus bovis, S. equines and possibly related taxa. Strains presently designated S. bovis and S. equines were found to be very heterogeneous. The type strains of S. bovis and S. equines were found to be genetically closely related (> 70 % DNA homology) and represent a single species. Strains of S. equines from pigs and chickens were found to be sufficiently distinct from the other taxa examined to warrant a new species, S. alactolyticus sp. nov. Some atypical S. bovis strains from straw and cattle also formed a distinct group on the basis of DNA/DNA homologies. These strains were biochemically quite distinct from the other taxa examined and are considered to represent a new species, for which the name S. saccharolyticus sp. nov. is proposed.