Clostridium felsineum
Cultural characteristics
Biochemical characters
Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster XI (Clostridium non
sensu stricto),
Clostridium felsineum (Carbone and Tombolato 1917) Bergey et al. 1939.

Historical synonyms:
Bacillus felsineus Carbone and Tombolato 1917, Clostridium felsinus (Carbone and Tombolato 1917) Bergey et
al. 1930,
Clostridium felsinae (Carbone and Tombolato 1917) Bergey et al. 1934.
Gram-positive (Gram-negative in older cultures), straight rods, 0.5-1.3 x 3.1-25.7 µm,  
cells occur singly, in pairs, and in short or long chains. Motile by peritrichous flagella
(motility may be lost in cultures that have been maintained in the laboratory for many
years). Spores are oval, subterminal, swelling the cell; spores are difficult to detect,
but usually can be found in PYG or PY-starch broth cultures incubated for 3–5 days.
Grow very poorly if at all on anaerobic blood agar or egg-yolk agar plates. Slight growth
in nutrient broth without fermentable carbohydrate; abundant growth in broth with
fermentable carbohydrate, ropy sediment. Surface colonies on brain heart infusion
agar roll streak tubes after incubation for 2-4 days are 1-4 mm in diameter, circular,
flat to low convex, translucent to opaque, with a mottled or granular surface, a pebbled
or mosaic internal structure, and an entire to slightly scalloped or lobate margin. They
may be white, yellow, orange, or brownish. When slight growth occurs on anaerobic
blood agar plates, colonies are beta-hemolytic.
Cultures in PYG broth are turbid with a heavy, ropy or flocculent, often dark orange  sediment and have a pH of 4.7-5.4 after incubation
for 24 h. Abundant gas is produced in PYG deep agar cultures. Products in PYG broth culture are butyric and acetic acids and butanol,
abundant hydrogen.
Growth is inhibited by 6.5% NaCl,  20% bile, or a pH of 8.5. Optimum temperature for growth is 37 ºC; weak growth at 25 ºC. Can grow
at 45 ºC.
Isolated from rotting flax, soil in the USA and Antarctica, human feces.
Susceptible to clindamycin, erythromycin, penicillin G, and tetracycline.
Spore suspensions of a strain of
Clostridium felsineum will germinate in and lyse tumor tissue but not healthy tissue in mice.
Destruction of the tumor tissue, however, is neither complete nor permanent.
Atmospheric N
2 is fixed.
Nonpathogenic for laboratory animals. Culture supernatants are nontoxic to mice. Toxin is not produced.
  1. N.A. Logan and P. De Vos, 2009. Genus I. Clostridium Prazmowski 1880. 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, 738-828.
  2. Smith L.D.S. and Hobbs G., 1974. Genus III. Clostridium Prazmowski 1880. In: (Eds.) Buchanan R.E. and Gibbons N.E., Bergey’s
    Manual of Determinative Bacteriology, Eighth Edition, The Williams & Wilkins Company, Baltimore, 551-572.
Milk reaction is positive (curd production). Meat digestion is negative.

Positive results for H
2 production, esculin hydrolysis, gelatin hydrolysis, neutral red reduction, substrate utilized and/or acid produced
from: arabinose (weak), cellobiose (weak), dulcitol, fructose, galactose, glucose, lactose (weak), mannose, rhamnose (weak),
salicin, sucrose & xylose.

Negative results for casein hydrolysis, H
2S production, indole production, lecithinase, lipase, nitrate reduction, urease, substrate
utilized and/or acid produced from: amygdalin, glycerol, inositol, mannitol, melezitose, melibiose, ribose, sorbitol, sorbose &

Variable results for resazurin reduction, starch hydrolysis, Voges-Proskauer reaction, substrate utilized and/or acid produced from:
glycogen, inulin, maltose, raffinose & starch.
(c) Costin Stoica
Culture media
Biochemical tests
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