oxygen. Rough and smooth colonies are pro- duced. Agar deep colonies (yeast autolysate and C2H5OH) : Small, 1 to 3 mm in diameter after 2 to 3 days ; two types are formed : a) fluffy spheres with dense nuclear centers and fila- mentous peripheries; b) compact, lenticular colonies. Little gas is produced. Plain broth: Xo growth. Glucose broth: Xo growth. Milk or iron-milk (Spray) : Xo growth. Indole production not recorded (probably negative). Ethanol is converted to caproic acid. Glucose and other carbohydrates not fer- mented. Cellulose not fermented. X'itrite production not recorded (probably negative) . Atmospheric nitrogen fixed, though less actively than by Clostridium -pasteurianum Winogradsky (Rosenblum and Wilson, Jour. Bact.,57, 1949,413). Coagulated albumin: No liquefaction. Blood serum: X"o liquefaction. Brain medium: No digestion or blacken- ing. Anaerobic. Optimum temperature, about 34° C. Grows between 19° and 37° C. Chemical tolerance: Optimum pH, about 6.8. Range for growth, pH 6.0 to 7.5. Probably not pathogenic. Distinctive characters: Large size of cells and slow growth, accompanied by non- putrefactive odor of caproic acid and of higher alcohols. Growth is exceptionally favored by synergistic association with Methanohacterium omelianskii Barker. In pure culture a high concentration of yeast autolysate is required. Caproic acid is pro- duced from ethanol. Source: Isolated from black mud of fresh water and of marine origin. Habitat: Not determined. Presumably widely dispersed in nature. 52. Clostridium acidiurici (Liebert, 1909) Barker, 1938. {Bacillus acidi urici Liebert, Koninkl. Akad. v. Wetensch., Proc. Sect. Sci., Amsterdam, 12, 1909, 55; Barker, Jour. Bact.,3e, 1938,323.) a.ci.di.u'ri.ci. L. adj. acidus sour; M. L. noun acidum acid; Gr. noun urum urine; M.L. adj. uricus pertaining to urine; M.L. acidum uricum uric acid; M.L. gen. noun acidiurici of uric acid. Straight rods, 0.5 to 0.7 by 2.5 to 4.0 mi- crons. Spores ovoid, 0.9 by 1.1 microns, terminal, swelling the cells. Motile by means of peritrichous flagella. Most strains are Gram-negative; a few strains are weakly Gram-positive, quickly becoming Gram- negative. Iron-gelatin (Spray): No growth. Plain deep agar: No growth. Uric acid agar surface colonies (anaero- bic) : Variable with the strain and with the moisture of the medium. Colonies, 1 to 2 mm in diameter, opaque, white, raised, round, smooth edged, with concentric surface markings and of rubbery consistency. Other colonies may be very thin, soft, transparent, with fimbriate projections, spreading to cover almost the entire plate. Intermediate colony tj^pes also observed. Uric acid agar deep colonies: Whitish, compact, lobate, 1 to 2 mm in diameter, with irregular edge; surrounded by a temporary zone of precipitated ammonium ureate which gradually disappears. Yeast autolysate tryptone glucose semi- solid agar: No growth (Barker and Beck, Jour. Bact.,4S, 1942,291). Plain broth: No growth. Glucose broth: No growth. Iron-milk (Spray) : N^o growth. Indole production not recorded (prob- ably negative). Glucose and other carbohydrates not fermented. Cellulose not fermented. Nitrite production not recorded (prob- ably negative). Atmospheric nitrogen not fixed (Rosen- blum and Wilson, Jour. Bact., 57, 1949, 413). Coagulated albumin: No liquefaction. Blood serum: No liquefaction. Brain medium: No digestion or blacken- ing. Anaerobic. Optimum temperature, about 35° C. Optimum reaction, about pH 7.5; lower limit for growth, about pH 6.5.
