Streptococcus thermophilus.

Streptocus tmophilus, as a species designation (Orla-Jensen, 1919), has included those members of the nonhemolytic streptococci that possess the unusual combination of characteristics of extreme salt sensitivity, nonobligate thermophily, a rigorous fermentative pattern with respect to certain sugars (Sherman, 1937), and, based upon attempts to culture on synthetic media, a notoriety for nutritional fastidiousness that exceeds that of Streptococcus pyogenes. In recent studies concerning the nutritional demands and synthetic capabilities of several cultures as circumscribed by the above mentioned cultural characteristics, we believe that we have acquired sufficient data to provide nutritional evidence as an aid to and as a criterion for the recognition of Streptococcus ermophilus as a valid species.