Tyrosine agar slants: Growth same as on agar. Broth: Clear with heavy, wrinkled, waxy, tough pellicle. Variations: Flocculent or uniform turbidity with or without fragile pellicle. NaCl broth: Good growth up to a con- centration of 7 per cent NaCl; growth in a few cases in 10 or 12 per cent. Milk: Slowly peptonized, usually be- coming alkaline. Milk agar streak plate : Usuallj^ there is a wide zone of hydrolysis of the casein. Potato: Growth heavy, wrinkled to coarsely folded, spreading. Offwhite, yellow, pink or brown. Variations: Slimy, soft, thin, warty. Acid but no gas (with ammonium salts as source of nitrogen) from arabinose, xylose, glucose, sucrose and mannitol. Usually no acid produced from lactose. Starch is hydrolyzed. Acetylmethj'lcarbinol produced (37° C. better incubation temperature than 32° C). pH of glucose broth cultures is 5.0 to 8.6 in 7 days. Citrates utilized. Nitrites produced from nitrates. No gas produced from nitrate broth under ana- erobic conditions. Aerobic, certain strains facultatively anaerobic. Growth scant, if any, in glucose broth under anaerobic conditions; pH of 14-day cultures is 5.5 or higher. Temperature relations: Optimum growth temperatures lie between 28° and 40° C. The maximum temperature for growth is usually 50° C, but some cultures find 40° too warm for growth while still others will grow even up to 55° C. Accessory growth factors not essential. Lecithinase not produced. Antibiotics obtained from cultures of certain strains are subtilin (Jansen and Hirschmann, Arch. Biochem., 4, 1944, 297), bacillin (Foster and Woodruff, Jour. Bact., 51, 1945, 363), subtenolin (Hirschhorn, Bucca and Thayer, Proc. Soc. Exp. Biol, and Med., 67, 1948, 429), bacillomycin (Landy, Warren, Rosenman and Colio, Proc. Soc. Exp. Biol, and Med., 67, 1948, 539) and oth- ers. Source: Isolated from infusions of lentils, cheese, white beets and hay (Cohn). Habitat: Widely distributed in soil and decomposing organic matter; also common as a laboratory contaminant. 6a. Bacillus subtilis var. aterrimus (Leh- mann and Neumann, 1896) Smith et al., 1946. (Potato bacillus, Biel, Cent. f. Bakt., II Abt., 2, 1896, 137; Bacillus aterrimus Lehmann and Neumann, Bakt. Diag., 1 Aufl., £, 1896, 303; Smith, Gordon and Clark, U. S. Dept. Agr. Misc. Pub. 559, 1946, 64.) a.ter'ri.mus. L. sup. adj. aterrimus very black. The description of Bacillus subtilis will serve for var. aterrimus with the additional statement that a blue-black to black pig- ment is formed on media containing a car- bohydrate utilized by the organism. The ability to form black pigments, however, may be lost and the cultures stabilized in the colorless condition (Smith et al., ibid., 9; also see op. cit., 1952, 29); they are then indistinguishable from cultures of Bacillus subtilis. Source: Isolated from rye bread in a moist chamber used for growing aspergilli (Biel). Habitat: Widely distributed in soil, air and decomposing carbonaceous materials. 6b. Bacillus stibtilis var. niger (Migula, 1900) Smith et al., 1946. (Bacillus laciis niger Gorini, Gior. d. Reale Soc. Ital. d'Ig., 16, 1894, 9; also see Cent. f. Bakt., I Abt., Orig., 20, 1896, 94; Bacillus niger IMigula, System der Bakterien, 2, 1900, 636; Smith et al., U. S. Dept. Agr. Misc. Pub. 559, 1946, 66.) ni'ger. L. adj. niger black. The characterization of Bacillus subtilis will serve for var. niger by adding the state- ment that media containing tyrosine are blackened. The ability to form black pig- ment, however, may be lost and the cultures stabilized in the colorless condition; then they cannot be distinguished from Bacillus subtilis. Source: Isolated from milk. Habitat: Widely distributed in soil, dust and decomposing materials.
