FAMILY VII. MICROCOCCACEAE 



475 



B. None or only slight fermentation of sugars. Glycine fermented. 



1. Gelatin liquefied; cell size variable. 



9. Peptococcus glycinophilus . 



10. Peptococcus variabilis. 



2. Gelatin not liquefied; cell size uniform. 



11. Peptococcus anaerobius. 



1. Peptococcus niger (Hall, 1930) Kluy- 

 ver and van Niel, 1936. {Micrococcus niger 

 Hall, Jour. Bact., 20, 1930, 409; Kluyver and 

 van Niel, Zent. f. Bakt., II Abt., 94, 1936, 

 400.) 



ni'ger. L. adj. niger black. 



Small spheres, 0.6 micron in diameter, 

 occurring in irregular masses, occasionally 

 in pairs. Gram-positive. 



Gelatin: After 5 days a dark sediment is 

 produced which graduall}' gets more and 

 more intensely black. No liquefaction. 



Deep agar colonies: Slow growth. At 

 first very tiny, colorless, irregularly globu- 

 lar, smooth, dense. Small bubbles of gas 

 are sometimes produced. After several days 

 colonies become brown, then black. If ex- 

 posed to air, colonies fade to a dull gray. 

 Medium not discolored. 



Blood agar slant colonies: After 4 or 5 

 days, minute, black, round, smooth, glisten- 

 ing, 0.5 mm in diameter. Non-hemolytic. 



Coagulated blood serum: Minute, brown 

 colonies appear on the 8th day. No liquefac- 

 tion. 



Broth: After 4 or 5 days, uniform turbid- 

 ity and slight production of gas which con- 

 tains hydrogen sulfide. Black sediment. 



Brain medium: Turbid after 4 or 5 days 

 at 37° C. Uniform gas production about the 

 6th day. Discoloration of the medium not 

 marked. 



Milk: No change. 



No acid from carbohydrates. Black sedi- 

 ment produced. 



Strict anaerobe. 



Optimum temperature, 37° C. No growth 

 below 30° C. 



Non-pathogenic for guinea pigs and 

 rabbits. 



Distinctive characters: Formation of a 

 water-insoluble, black pigment. Growth 

 slow, visible after 2 to 4 days. 



Source: Isolated from the urine of an 

 aged woman. 



Habitat: Unknown. 



2. Peptococcus activus (Prdvot and 

 Taffanel, 1945) Douglas, comb. nov. {Staph- 

 ylococcus activus Pr^vot and Taffanel, Ann. 

 Inst. Past., 71, 1945, 152.) 



ac'ti.vus. L. adj. activus active. 



Original description supplemented by ma- 

 terial from Foubert (Thesis, Univ. of Wash- 

 ington, 1947) and Whiteley (Thesis, Univ. 

 of Washington, 1951). 



Spherical cells, 0.75 to 1.0 micron in di- 

 ameter, occurring singly, in pairs, tetrads 

 and irregular groups. Non-motile. Not en- 

 capsulated. Gram-positive. 



Gelatin: Liquefaction. 



Agar colonies: 0.5 to 1.0 mm in diameter, 

 smooth, entire, convex, opaque, grayish 

 white, butyrous. 



Growth in fluid medium: In peptone yeast 

 extract broth, growth moderately heavy in 

 72 hours; no odor; coarsely granular; gas 

 is produced. Growth not enhanced by glu- 

 cose. 



Litmus milk: Reduced. 



Indole is produced. 



Hydrogen sulfide is produced. 



Acid from glucose, galactose, fructose, 

 mannose, maltose and sucrose. No acid from 

 raffinose, starch, inulin, salicin, glycerol or 

 mannitol. Cell suspensions ferment serine, 

 threonine and purines to CO2 , NH3 , H2 

 and unidentified products. 



Nitrites produced from nitrates; nitrites 

 are reduced. 



Egg albumen, beef serum and casein at- 

 tacked slowly. 



Coagulase-negative. 



Catalase-positive. 



Anaerobic. 



Optimum temperature, 37° C. Growth oc- 

 curs between 30° and 37° C. 



Optimum pH, between 7.0 and 8.0; pH 

 range, 6.5 to 8.5. 



Non-hemolytic. 



Distinctive characters: Gas production; 

 active utilization of glucose and other 

 sugars; proteolytic activity. 



