PHENOTYPIC CHARACTERIZATION OF ORAL STREPTOCOCCI BY CLASSICAL METHODS

The phenotypic characteristics of 21 5 strains of oral streptococci we re compared on the basis of the results of sorbitol, raffinose and tre halose fermentation, ammonium from arginine production, aesculin hydro lysis, H2O2 production, susceptibility to 2 U bacitracin, and growth i n 4% NaCl solution. Eleven different species were identified. Among th e most noteworthy findings were the low number of H2O2-producing strai ns of Streptococcus sobrinus, the effective discrimination between Str eptococcus sanguis and Streptococcus mitis on the basis of raffinose f ermentation, and the phenotypic similarity between Streptococcus orali s and the former mutans group. To avoid the creation of new species, t he term biotype is proposed to designate phenotypically distinct organ isms which do not qualify as different species.