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Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster XI (Clostridium
non-sensu stricto),
Clostridium malenominatum (Weinberg, Nativelle and Prévot 1937) Spray 1948.

Historical synonyms:
Bacillus malenominatus Weinberg, Nativelle and Prévot 1937.
Gram-positive or -negative, straight rods, 0.3-0.9 x 1.4-10.8 µm, occuring singly or in
pairs. Variable motility. Spores are oval/round, subterminal/terminal, swelling the cell;
sporulation occurs most readily on chopped-meat slants or on egg-yolk agar plates
incubated at 30 ºC for one week.
Surface colonies on blood agar plates are pinpoint - 2 mm, circular or slightly
irregular, convex or raised, gray-white, and translucent, with a crystalline, mottled or
granular internal structure, and an entire, erose or scalloped margin; the surface may
be smooth or lumpy. Hemolysis is variable. No aerotolerance. Moderate growth in
nutrient broth with or without fermentable carbohydrate. Cultures in PYG broth are
turbid with a smooth or ropy sediment and have a pH of 6.1-6.5 after incubation for 1
week. Growth is inhibited by 6.5% NaCl, 20% bile, or a pH of 8.5. Optimum
temperature for growth is 37 ºC. Grow at 25 ºC and at 45 ºC (weak). Products in PYG
broth:  acetate, butyrate    and abundant H
2. Moderate amounts of gas are produced in
PYG deep agar cultures.
Isolated from human feces, chicken cecal contents, soil, human and animal infections. Susceptible to chloramphenicol & erythromycin.
Supernatant fluids are not toxic to mice. Cultures have been reported pathogenic for the Guinea pig and rabbit.
  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 and meat digestion are negative. Hydrogen production is intense.

Positive results for ammonia, H
2S & indole production.

Negative results for casein hydrolysis, esculin hydrolysis, lecithinase, lipase, starch hydrolysis, urease, Voges-Proskauer reaction,
substrate utilization and/or acid production from: adonitol, amygdalin, arabinose, cellobiose, dulcitol, fructose, galactose, glucose,
glycogen, glycerol, inositol, inulin, lactose, maltose, mannitol, mannose, melezitose, melibiose, raffinose, rhamnose, ribose, salicin,
sorbitol, sorbose, starch, sucrose, trehalose & xylose.

Variable results for gelatin hydrolysis (after 3 weeks) & nitrate reduction.
Clostridium malenominatum
(c) Costin Stoica
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