Bacillus megaterium
Vacuolate / foamy cells. Bacillus megaterium
Bacillus megaterium. Gram-stain, old culture
Bacillus megaterium colonies on Mueller-Hinton agar
Cultural characteristics
Biochemical characters
Phylum Firmicutes, Class Bacilli, Order Bacillales, Family Bacillaceae, Genus Bacillus, Bacillus megaterium de Bary 1884.

Possible synonyms:
B. tumescens Zopf 1885, B. oxalaticus Migula 1894, B. ruminatus Gottheil 1901, B. graveolens Gottheil 1901, B.
Gottheil 1901, B. silvaticus Neide 1904, B. malabarensis Lohnis and Pillai 1907, B. danicus Lohnis and Westermann 1909,
B. carotarum Koch 1888 (differs from typical members), possible synonyms of B. carotarum (B. simplex Gottheil 1901, B. cohaerens
Gottheil 1901,
B. cobayae Stapp 1920, B. capri Stapp 1920, B. musculu Stapp 1920), B. flexus Batchelor 1919 (but failling to produce
acid from pentoses and to deaminate phenylalanine).
Gram-positive, 2.0-5.0 x 1.2-1.5  μm, motile, peritrichous flagella. Spores are
ellipsoidal or spherical, central, paracentral or subterminal; not  swelling the
sporangia. Capsule might be present. Cells grown on glucose agar produce large
amounts of storage material, giving a vacuolate or foamy appearance.
Colonies are round to irregular, with entire to undulate margins. May become yellow
and then brown or black after prolonged incubation.
Hemolytic. Aerobic, do not grow anaerobically. Growth temperature  from  3-20 ºC  to  
35-45 ºC. Optimum temperature is 30 ºC. The temperature range of a water isolate
from an Antarctic geothermal island was 17-63 °C, with an optimum of 60 °C.
On nutrient agar grow heaped and nonspreading, glossy, sometimes slightly
rugose;mucoid on glucose agar. Aged cultures may become yellow,  brown or black.
Growth active at pH 5.7-7.0
Grow in7 % NaCl. NaCl, allantoin or urate are not required for growth.
Spores occur in soil, feces. Isolated from foods and clinical specimens. Found in the
gut of a termite,
Zootermopsis angusticollis. Antibiotic producer („megacin”). No
growth in the presence of lysozyme.
Considered to be not pathogenic. Used as biofertilizer in agriculture (admin note).
  1. Bîlbîie V., Pozsgi N., 1985, Bacteriologie Medicală, vol.ll, Ed. Medicală, Bucureşti.
  2. Gordon R.E., Haynes W.C., Pang C.H. (1973) – The genus Bacillus . Agriculture
    Handbook No. 427, U.S.D.A., Washington D.C.
  3. 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.
  4. Răducănescu H., Valeria Bica-Popii, 1986, Bacteriologie veterinară, Ed. Ceres,
  5. 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, hydrolysis of starch, utilization of citrate, hydrolysis of
esculin, beta-galactosidase, phenylalanine deamination, hydrolysis of gelatin,
hydrolysis of casein, acid production from: L-arabinose, N-acetyl-D-glucosamine,
amygdalin, arbutin, D-cellobiose, D-fructose, galactose, beta-gentibiose,
meso-inositol, inulin, lactose, glycogen, glucose, glycerol, maltose, D-mannitol,
D-melibiose, D-raffinose, ribose, salicin, starch, sucrose, trehalose, and D-xylose.

Negative results for Voges-Proskauer, indole production, arginine dihydrolase, lysine
decarboxylase, ornithine decarboxylase, tryptophan deaminase, hydrolysis of urea,
egg yolk reaction, acid production from: methyl beta-xyloside, D-arabinose, adonitol,
L-arabitol, dulcitol, erythritol, D- or L-fucose, 2- or 5-ketogluconate, lyxose,
D-mannose, rhamnose, and sorbose.

Variable results for oxidase, degradation of tyrosine, nitrate reduction, acid production
from: D-arabitol, gluconate, D-melezitose, sorbitol, and xylitol.
(c) Costin Stoica
Culture media
Biochemical tests
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