|(A) vegetative cells by Gram staining
(B) spores by Malachite-green staining
|Bacillus firmus colonies on Sheep Blood Agar
Phylum Firmicutes, Class Bacilli, Order Bacillales, Family Bacillaceae, Genus Bacillus, Bacillus firmus Werner (1933).
Differentiated in two biovars by some sugars fementation and substrates utilization as
sole carbon source.
Possible synonym: Bacillus imomarinus ZoBell and Upham 1944.
Gram-positive, 1.2-3.8 / 0.6-1.0 µm, motile by peritrichous flagella.
Spores are oval or cylindrical, subterminal, paracentral or central, rarely swelling the
On TSA at 30 ºC, after 3 days, colonies are 1-12 mm in diameter, creamy-yellow to
pale orange-brown , with margins that vary from entire to finely rhizoidal, and surface
appearances that are egg-shell to glossy, sometimes with granular or zoned areas in
Facultatively anaerobic. Maximum temperature 40-50 ºC; minimum temperature, 5-20
ºC, optimum 20-30 ºC. Grows in 2-7% NaCl. Optimum pH 7-9 (growth range 6-11).
NaCl, allantoin or urate are not required for growth.
Sparsely represented in nature, has been isolated mainly from soil.
- Gordon R.E., Haynes W.C., Pang C.H. (1973) – The genus Bacillus. Agriculture Handbook No. 427, U.S.D.A., Washington D.C.
- 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.
- Buiuc D., Negut M. , 2009. Tratat de Microbiologie Clinica, editia a III-a, Bucuresti.
- 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,
decomposition of casein (weak), gelatin liquefaction, acid from: glucose, mannitol,
glycerol, starch, N-acetyl-D-glucosamine, maltose, sucrose & trehalose.
Negative results for Voges-Proskauer test, resistance to lysozyme, utilization of citrate
and propionate, indole production, arginine dihydrolase, lysine decarboxylase,
ornithine decarboxylase, H2S production, tryptophan deaminase, beta-galactosidase,
hydrolysis of urea, egg yolk reaction, acid production from: L-xylose, methyl
beta-xyloside, salicin, D- or L-arabinose, D-mannose, adonitol, amygdalin, D- or
L-arabitol, arbutin, cellobiose, dulcitol, erythritol, D- or L-fucose, galactose,
beta-gentibiose, gluconate, meso-inositol, inulin, 2- or 5-ketogluconate, lactose,
lyxose, melezitose, melibiose, raffinose, rhamnose, ribose, sorbitol, sorbose & xylitol.
Variable results for esculin hydrolysis, acid from: D-xylose, glycogen & fructose.
(c) Costin Stoica