tween 28° and 35° C. Maximum, usually between 40° and 45° C. Source: Isolated from cooked cabbage. Habitat : Widely distributed in soil, water, dust and decomposing materials. 2. Bacillus cereus Frankland and Frank- land, 1887. (Philosoph. Trans. Roy. Soc. London, 178, B, 1887, 279.) ce're.us. L. adj. cereus wax-colored, waxen. Rods, 1.0 to 1.2 by 3.0 to 5.0 microns, with square ends, usually occurring in short to long, tangled chains. When lightly stained, protoplasm granular or foamy. No shadow- forms. Not encapsulated. Motile. Gram- positive. Variations: 0.8 to 1.3 by 2.0 to 6.0 microns. Filaments. Ends rounded. Encap- sulated. Non-motile. Protoplasm stains uni- formly. Gram-variable. On glucose agar, rods are larger and more vacuolated and contain many, large, fat globules. Variation: Sometimes contain only a few, small, fat globules but always vacuolated when lightly stained. Spores, 1.0 to 1.5 microns, ellipsoidal, central or para-central. Thin-walled. Many formed in 18 to 24 hours. Variations: 0.5 to 1.2 by 1.3 to 2.5 microns. Few or none at 48 hours or longer. Sporangia not appreciably swollen. Gelatin stab: Rapid liquefaction. Gelatin agar streak plate: Wide zone of hydrolysis. Agar colonies: Large, rough, flat, irregular with whip-like outgrowths. Whitish with characteristic mottled appearance by trans- mitted light (resembling galvanized iron or moire silk). Variations: Thin and spreading, rough and arborescent, smooth and dense. Agar slants: Growth abundant, rough, opaque, whitish, non-adherent, spreading. Edge irregular with whip-like outgrowths. Variations: Relatively smooth. Very rough extending into the agar. Greenish yellow, diffusing pigment. Glucose agar slants: Growth abundant, heavier and softer than on agar. Glucose nitrate agar slants: Scant, if any, growth. Broth: Heav}'^, uniform turbidity with soft, easily dispersed sediment, with or without soft ring pellicle. Variations: Floc- culent growth. Firm pellicle. Milk: Rapid peptonization, with or with- out slight coagulation. Milk agar streak plate: Wide zone of hy- drolysis of the casein. Potato: Growth abundant, thick, spread- ing, soft, creamy white, sometimes with pinkish tinge. Variations: Growth re- stricted, thin, folded, dry or slimJ^ Potato darkened or orange-colored. Acid but no gas (with ammonium salts as source of nitrogen*) from glucose; also usually from sucrose, glycerol and salicin. No acid from arabinose, xylose or mannitol. Usually no acid from lactose. Starch hydrolyzed. Acetylmethylcarbinol produced. Citrates usually utilized as sole source of carbon. Nitrites usually produced from nitrates. Gas usually produced from nitrates under anaerobic conditions. Amino acids necessary for growth. Lecithinase produced. Aerobic, facultatively anaerobic. Growth in glucose broth under anaerobic condi- tions; pH usually below 5.2. Temperature relations: Optimum about 30° C. Maximum, between 37° and 48° C. Pathogenicity: Large doses of 24-hour broth cultures fatal to guinea pigs (Clark, Jour. Bact., 33, 1937, 435). Source: Isolated from dust. Habitat: Widely distributed in soil, dust, milk and on plant surfaces. 2a. Bacillus cereus var. mycoides (Fliigge, 1886) Smith et al., 1946. {Bacillus mycoides Flugge, Die Mikroorganismen, 2 Aufl., 1886, 324; Smith, Gordon and Clark, U. S. Dept. Agr. Misc. Pub. 559, 1946, 54.) my.co.i'des. Gr. noun myces fungus; Gr. noun eidus form, shape; M.L. adj. mycoides fungus-like. Bacillus cereus var. uiycoides is identical in all respects with Bacillus cereus except in the following characters :
- A major portion of the investigations of carbohydrate utilization reported by Smith
et al. (op. cit., 1952) was made with crude agar. Later, when refined agar was used, 0.02 per cent yeast extract was incorporated in the ammonium salts medium.
