DEGRADATIVE ENZYMES OF ORAL STREPTOCOCCI

Members of the Streptococcus sanguis group (SSG) and Streptococcus milleri group (SMG) were screened for their ability to produce glycosidase, arylamidase (peptidase), protease, dextranase and glycosyltransferase activities. Species within each group produced unique patterns of activity. The most commonly produced glycosidases were beta-D-glucosidase, beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and N-acetyl-beta-D-galactosaminidase and the least commonly produced glycosidase activity was beta-fucosidase with Streptococcus intermedius (SMG) being the only species capable of producing the activity. For arylamidase activity, the most commonly produced type was lysine-arylamidase, Glycosidase and arylamidase activities were localized to particular sub-cellular fractions. alpha-galactosidase was found only in culture supernatant fluids whereas N-acetyl-beta-D-glucosaminidase was found in all fractions; the culture supernatant, cell wail, cell membrane and cytoplasm. No arylamidase activity was seen in culture supernatants. Phe-arg-arylamidase was found only in cytoplasmic fractions whereas val-pro-argarylamidase was found in cell walls, cell membranes and cytoplasmic fraction. Protease activity was measured as the degradation of bovine serum albumin (BSA) and casein. Casein was degraded by a number of strains whereas no species/strains were able to degrade BSA. Streptococcus intermedius, Streptococcus constellatus (SMG), Streptococcus mitior and Streptococcus defectivus (SSG) were the only species that produced hyaluronidase and no species produced chondroitin sulphatase. The groups were also examined for their abilities to produce glycosyltransferase and dextranase. Strep. sanguis, Streptococcus gordonii, Streptococcus mitis and Streptococcus oralis produced glucosyltransferase and, with the exception of the latter species, fructosyltransferase. No species within the SMG was capable of producing either glycosyltransferase. No species within the SSG or SMG was able to produce dextranase activity. The ability of species to produce different types of enzymes was related to their taxonomy, allowing the differentiation of several new taxonomic types within the SSG and may be related to pathogenesis.