Phylum Firmicutes, Class Bacilli, Order Lactobacillales, Family Streptococcaceae, Genus Streptococcus, Streptococcus sobrinus
Synonym: Streptococcus mutans subsp. sobrinus Coykendall 1974.
Non-groupable with Lancefield antisera. Member of the "Mutans group".
Gram positive cocci, 0.5 µm in diameter, arranged in pairs to medium-long chains,
Colonies on agar containing sucrose are about 1 mm in diameter, rough, and
heaped and often have droplets of liquid at the top or the border. Nonhaemolytic,
some strains are alpha-hemolytic.
Facultatively anaerobic, optimal growth at 37.0 ºC. Growth at 45 ºC is variable, no
growth at 10 ºC. Grow on media: Trypticase soy agar with defibrinated sheep blood.
Growth is enhanced in a low oxygen atmosphere.
Human oral cavity inhabitant. Isolated from teeth surface.
Human commensal associated with the development of tooth decay.
- Holt J.G., Krieg N.R., Sneath P.H.A., Staley J.T. and Williams S.T., 1994. Bergey's Manual of Determinative Bacteriology, Ninth
Edition, Williams & Wilkins, A Waverly Company, Baltimore, pp 527-558.
- Robert A. Whiley and Jeremy M. Hardie, 2009. Genus I. Streptococcus Rosenbach 1884, 22AL. In: (Eds.) P.D. Vos, G. Garrity, D.
Jones, N.R. Krieg, W. Ludwig, F.A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3:
The Firmicutes, Springer, 655-711.
- Coykendall A.L.: Streptococcus sobrinus nom. rev. and Streptococcus ferus nom. rev.: habitat of these and other mutans
streptococci. Int. J. Syst. Bacteriol., 1983, 33, 883-885.
An adhesive glucan is produced from sucrose. Hydrogen peroxide is produced.
Positive results for alpha-glucosidase, Voges–Proskauer reaction, acid production from: cellobiose (delayed reaction), glucose,
maltose, mannitol (delayed reaction), mannose, sucrose, tagatose & trehalose.
Negative results for alkaline phosphatase, arginine hydrolysis, esculin hydrolysis, alpha-arabinosidase, alpha- or beta-
galactosidase, alpha- or beta-fucosidase, beta-glucosidase, beta-glucuronidase, N-acetylgalactosaminidase, N-
acetylglucosaminidase, pyrrolidonyl arylamidase, glycyl tryptophan arylamidase, hyaluronidase, sialidase, urease, acid production
from: adonitol, amygdalin, arabinose, arbutin, dulcitol, erythritol, esculin, gluconate, glycerol, glycogen, inositol, melibiose, methyl D-
glucoside, methyl D-mannoside, methyl D-xyloside, N-acetylglucosamine, melibiose, melizitose, pullulan, raffinose, rhamnose,
salicin, sorbose, starch & xylose.
Variable acid production from: galactose, lactose & sorbitol.
(c) Costin Stoica