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.
