Bacillus cereus
Bacillus cereus cells and spores
Bacillus cereus haemolytic, R-type colonies
Cultural characteristics
Biochemical characters
Phylum Firmicutes, Class Bacilli, Order Bacillales, Family Bacillaceae, Genus Bacillus, Bacillus cereus Frankland and Frankland
(1887). 42 serovars are recognized on the basis of H-antigens .
Historical synonyms:
Bacillus cereus var. fluorescens Laubach (1916) (distinctive property : produces yellow-green fluorescent
Bacillus cereus var. albolactis (Migula) de Soriano (1935) (acid formed from lactose), Bacillus albolactis Migula (1900).

Phenotypically is very closed to other members of the 'Bacillus cereus' group:
Bacillus  anthracis, Bacillus mycoides, Bacillus
, Bacillus thuringiensis and Bacillus weihenstephanensis. Genetic evidence supports the recognition of members of
the Bacillus cereus group as one species, but practical considerations (virulence characters) argue against such a move.
Gram-positive, 1.0-1.2 x 3.0-5.0 μm, motile with peritrichous flagella. Ellipsoidal,
central or paracentral spores, rarely distending  the sporangia. Sometimes spores
may be cylindrical. Capsule is not present. The bacilli tend to occur in chains.
Large, R-type, irregular, opaque colonies, sometimes with a waxy aspect. On agar,
colonies are large, 2-7 mm in diameter; smooth and moist colonies are possible;
usualy are whitish to cream, but some strains may produce a pinkish brown pigment or
a yellow diffusible pigment or a yellowish-green fluorescent pigment. Fresh plate
cultures commonly have a mousy smell. Hemolytic on blood agar.
In liquid media form moderate or intense turbidity, not characteristic.
Facultatively anaerobic. Grow in nutrient broth and in  2- 7% NaCl. Good growth on
nutritive agar; better  on nutritive agar with 7-10% sheep blood. Growth at 5,7 pH.
Temperature range 20-40 ºC. Variable growth at 10 and 45 ºC; no growth at 5 ºC
Psychrotolerant strains growing at 60 ºC have been isolated.
NaCl, allantoin or urate are not required for growth.
Resistant to lysozyme. Spores are widespread (soil, water, air, foods etc).
Synthesize heat-stabile emetic toxin, cytotoxin, hemolysin, mice lethal toxin, enterotoxin, bacteria lytic enzymes, proteolytic enzymes &  
phospholipase C.
B. cereus is a pathogen of humans (and other animals), causing foodborne illness (diarrheal-type and emetic-type syndromes) and
opportunistic infections (endophtalmia, keratitis, septicemia, meningitis, endocarditis, pneumonia, osteomielitis, urinary infections,  
cutaneous infections. It also causes infections in domestic animals (mastitis and abortion in cattle).
  1. Gordon R.E., Haynes W.C., Pang C.H. (1973) – The genus Bacillus . Agriculture Handbook No. 427, U.S.D.A., Washington D.C.
  2. Buchanan R.E., Gibbons N.E., Cowan S.T., Holt J.G., Liston J., Murray R.G.E., Niven C.F., Ravin A.W., Stanier R.W. ( 1974) –  
    Bergey’s Manual of Determinative Bacteriology, Eight Edition, The Williams & Wilkins Company, Baltimore.
  3. Bîlbîie V., Pozsgi N., 1985, Bacteriologie Medicală, vol.ll, Ed. Medicală, Bucureşti.
  4. H. Răducănescu, Valeria Bica-Popii, 1986. Bacteriologie veterinară, Ed. Ceres, Bucureşti.
  5. Buiuc D., Negut M. , 2009. Tratat de Microbiologie Clinica, editia a III-a, Editura Medicala, Bucuresti.
  6. Logan N. A.,2005. Bacillus anthracis, Bacillus cereus, and other aerobic endospore-forming bacteria. In: Boriello S.P., Murray P.R.,
    Funke G. (Ed),Topley & Wilson’s Microbiology & Microbial Infections.Bacteriology, Vol. 2, pp. 922-952.
  7. N.A. Logan and P. De Vos, 2009. Genus I. Bacillus Cohn 1872. In: (Eds.) P.D. Vos, G. Garrity, D. Jones, N.R. Krieg, W. Ludwig, F.A.
    Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3: The Firmicutes, Springer, 21-127.
Positive results for hydrolysis of gelatin, egg yolk reaction, catalase, hydrolysis of
starch (negative for emetic biotype), Voges-Proskauer, hydrolysis of esculin, reduction
of nitrate to nitrite, hydrolysis of casein, decomposition of tyrosine, citrate utilization,
formation of alkali in litmus milk, acid production from glucose, trehalose, glycogen
(negative for emetic biotype), glycerol (variable for emetic biotype),
N-acetyl-D-glucosamine, arbutin, fructose, maltose, ribose & trehalose.

Negative results for oxidase, beta-galactosidase, lysine decarboxylase, ornithine
decarboxylase, deamination of phenylalanine, indole, gas production from
carbohydrates, acid production from: mannitol, arabinose, xylose,  D-mannose,
alpha-metyl- D-mannoside, methyl beta-xyloside, adonitol, amygdalin, D- or
L-arabitol, dulcitol, erythritol, D- or L-fucose, galactose, meso-inositol, inulin,
2-ketogluconate, 5-ketogluconate, lactose, lyxose, melezitose, melibiose, raffinose,
rhamnose , sorbitol, sorbose & xylitol.

Variable results for hydrolysis of urea, digestion of litmus milk, arginine dihydrolase,
acid production from: salicin, starch, cellobiose, beta-gentibiose, gluconate &
(c) Costin Stoica
Culture media
Biochemical tests
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