FAMILY XIII. BACILLACEAE 



617 



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. 



