524 



ORDER IV. EUBACTERIALES 



tinguished from Streptococcus faecalis by 

 serological type-specificity. 



Litmus milk: Acidified, curdled and pep- 

 tonized. The proteolysis of the milk is 

 usually characteristic in showing digestion 

 down one side of the tube. Litmus com- 

 pletely reduced before curdling. Old labora- 

 tory strains tend to lose their ability to 

 peptonize milk. 



Gelatin liquefied. 



16b. Streptococcus faecalis var. zy mo- 

 genes (MacCallum and Hastings, 1899) 

 Mattick, 1947. {Micrococcus zymogenes 

 MacCallum and Hastings, Jour. Exp. Med., 

 4, 1899, 521; Streptococcus zymogenes Hol- 

 land, Jour. Bact., 5, 1920, 226; Mattick, 

 Proc. Fourth Internat. Cong, for Micro- 

 biology, Copenhagen, 1947, 519.) 



zy.mo'ge.nes. Gr. noun zyme leaven, fer- 

 ment; Gr. V. gennaio to produce; M.L. adj. 

 zymogenes ferment-producing. 



This variety was regarded as a separate 

 species. Streptococcus zymogenes, in the 

 Manual, 6th ed., 1948, 327, but it is be- 

 lieved that the differences are not sufficient 

 to warrant species distinction. This variety 

 possesses the same characteristics as Strep- 

 tococcus faecalis except as given below. It 

 is a member of the enterococcus group and 

 Lancefield's group D. It can not be dis- 

 tinguished from Streptococcus faecalis by 

 serological type-specificity. 



Action on blood: Broad zoned hemolysis 

 (beta hemolytic). An acid-labile soluble 

 hemolysin is produced, but it is difficult to 

 demonstrate under the usual conditions of 

 testing. 



Litmus milk: Acidified, usually curdled, 

 with complete reduction of the litmus be- 

 fore curdling. May or may not peptonize. 

 The proteolytic strains show changes in 

 litmus milk similar to those effected by 

 Streptococcus faecalis var. liquefaciens. 



Gelatin may or maj^ not be liquefied. 



17. Streptococcus durans Sherman and 

 Wing, 1937. (Jour. Dairy Sci., 20, 1937, 165.) 



du'rans. L. part. adj. durans hardening, 

 resisting. 



Spherical to ovoid cells elongated in di- 

 rection of the chain; 0.5 to 1.0 micron in 



diameter. Occur mostly in pairs or short 

 chains. 



Serology: Belongs to Lancefield's group 

 D. Many serological types are known to 

 exist. No distinctive separation of the 

 serological types from those oi Streptococcus 

 faecalis and its varieties, although some 

 broad divisions can be made (Sharpe and 

 Shattock, Jour. Gen. Microbiol., 6, 1952, 

 150). 



Action on blood: Hemolytic (beta), but 

 the zones of hemolysis are generally less ex- 

 tensive than those produced by Streptococ- 

 cus faecalis var. zymogenes. Soluble hemoly- 

 sin difficult to demonstrate. 



Abundant growth with the production of 

 uniform turbidity and heavy sediment in 

 broth media containing fermentable carbo- 

 hydrate. 



Not fibrinolytic. 



Temperature relations : Growth at 10° and 

 45° C. Survives 60° C. for 30 minutes. 



Tolerance tests: Same as iox Streptococcus 

 faecalis . 



Litmus milk: Acidified, usually curdled, 

 with litmus reduction after curdling. No 

 proteolysis. 



Final pH in glucose broth, between 4.0 

 and 4.5. 



Acid from glucose, maltose and lactose. 

 Trehalose and salicin may or may not be 

 fermented. Ferments glycerol only aerobi- 

 cally. Sucrose and mannitol rarely fer- 

 mented. Arabinose, raffinose, inulin and 

 sorbitol not fermented. 



No polysaccharide synthesized from 

 sucrose. 



Starch or gelatin not hydrolj'zed. Sodium 

 hippurate may or may not be hydrolyzed. 

 Esculin split. 



Ammonia produced from arginine. 



Tyrosine is decarboxylated to yield 

 tyramine and carbon dioxide. 



Distinctive characters: As a member of 

 the enterococcus group, this species is 

 closely related to Streptococcus faecalis and 

 its varieties. Other than its hemolytic 

 properties, this species may be difficult to 

 distinguish from some cultures now classi- 

 fied as Streptococcus faecalis. However, in 

 contrast to the typical Streptococcus fae- 

 calis, this species fails to reduce litmus be- 



