Abstract
Strains of nutritionally variant streptococci, Streptococcus defectivus (n = 10) and Streptococcus adjacens (n = 20), were studied for the production of glycosidic and proteolytic enzyme activities. S. defectivus strains produced neuraminidase and alpha-fucosidase, while S. adjacens strains produced only neuraminidase. The S. adjacens strains produced a very wide range of proteolytic activities with the ability to hydrolyze the majority of aminopeptidase substrates tested, while S. defectivus strains hydrolyzed only a minority of aminopeptidase substrates. These data provide additional phenotypic characteristics which may be useful in distinguishing between these two species and suggest that they may have different nutritional requirements.