Phylum Firmicutes, Class Bacilli, Order Bacillales, Family Bacillaceae, Genus Bacillus, Bacillus mycoides Flugge (1886).
Synonym: Bacillus cereus var. mycoides Smith, Gordon and Clarck (1946).
Phenotypically is very closed to other members of the Bacillus cereus group: Bacillus anthracis, Bacillus cereus, Bacillus
pseudomycoides, 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. Bacillus mycoides is distinguished by its characteristic rhizoid colonies and
absence of motility. Bacillus pseudomycoides can only be separated from Bacillus
mycoides by DNA relatedness and some differences in fatty acid composition.
Gram positive rods, non-motile, 1.0-1.2 x 3.0-5.0 µm. Cells grown on glucose agar
produce large amounts of storage material,giving a vacuolate or foamy appearance.
Spores are ellipsoidal, central, paracentral or subterminal, not distending the
sporangia. Capsule not present. The bacilli tend to occur in chains.
Colonies are white to cream, opaque, and characteristically rhizoid; this ability to form rhizoid colonies may be lost. Facultatively
anaerobic. Maximum temperature, 35-40 ºC; minimum temperature, 10-15 ºC. Grow in anaerobic agar and in nutrient broth.
Growth in 7% NaCl is variable. Grow at pH 5.7 (also at pH 6 and 7).
Spores widespread (soil, water, air, foods etc). Can grow in the presence of lysozyme.
Tardive hemolysis, non-pathogenic for mouse.
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Bergey’s Manual of Determinative Bacteriology, Eight Edition, The Williams & Wilkins Company, Baltimore.
- Bîlbîie V., Pozsgi N., 1985, Bacteriologie Medicală, vol.ll, Ed. Medicală, Bucureşti.
- 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.
- 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 catalase, starch hydrolysis, reduction of nitrate to nitrite, casein
hydrolysis, esculin hydrolysis, Voges-Proskauer, gelatin hydrolysis, egg yolk reaction,
formation of alkali in litmus milk & acid production from N-acetyl-D-glucosamine,
glucose, trehalose, glycerol, starch & glycogen
Negative results for oxidase, gas from carbohydrates, indole production, deamination
of phenylalanine, acid production from arabinose, adonitol, D- or L-arabitol, dulcitol,
erythritol, D- or L-fucose, beta-gentibiose, gluconate, meso-inositol, inulin, 2- or
5-ketogluconate, lactose, lyxose, maltose, mannitol, D-mannose,
alpha-metyl-D-mannoside, melezitose, melibiose, raffinose, rhamnose, sorbitol,
sorbose, xylose, methyl beta-xyloside & xylitol.
Variable results for urease, nitrate reduction, decomposition of tyrosine, use of citrate,
alkaline digestion of litmus milk, beta-galactosidase, lysine decarboxylase, ornithine
decarboxylase, arginine dihydrolase, acid production from amygdalin, arbutin,
cellobiose, fructose, galactose, ribose, salicin & sucrose.
(c) Costin Stoica
|Bacillus mycoides rhizoid colony