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 H2. 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.
- 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,
- 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, H2S & 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.
(c) Costin Stoica