Phylum Firmicutes, Class Clostridia, Order Clostridiales, Family Clostridiaceae, Genus Clostridium, Cluster I (Clostridium sensu
stricto), Clostridium celatum Hauschild and Holdeman 1974.
Gram-positive straight or curved rods, 0.8-3.0 x 6.3 µm, occuring singly, in pairs or in chains, filaments. Nonmotile. Spores are oval,
terminal/subterminal/central, usually not swelling the cell; sporulation occurs most
readily on solid media (blood agar or egg-yolk agar plates or chopped-meat slants)
Surface colonies on blood agar plates are 2-7 mm in diameter, lobate to erose, flat to
low convex, translucent to opaque, white, with a granular or mottled internal structure.
Some strains were alpha-hemolytic, some were non-haemolytic on rabbit blood.
Cultures in PYG broth are turbid with a smooth or fluffy sediment and have a pH of 5.2-
5.5 after incubation for 1 week. Growth is stimulated by fermentable carbohydrates.
Growth is inhibited by 6.5% NaCl and 20% bile.
Grows optimally at 37 ºC. Variable, weak growth at 25 or 45 ºC. Products in PYG
broth: acetic and formic acids, ethanol and hydrogen. Slight to moderate gas is
produced in PYG deep agar cultures.
Isolated from human feces. Susceptible to chloramphenicol, clindamycin, penicillin G and tetracycline.
Nonpathogenic for laboratory animals.
- 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,
H2 is produced very abundantly. Milk reaction is positive (acidified and slightly curdled).
Positive results for esculin hydrolysis, H2S production from bisulfite not from sulphate, neutral red reduction, urease, substrate utilized
and/or acid produced from: amygdalin, cellobiose, fructose, galactose, lactose, maltose, mannose, salicin, sucrose & trehalose.
Negative results for indole production, lecithinase, lipase, starch hydrolysis, resazurin reduction, substrate utilized and/or acid
produced from: arabinose, glycogen, inulin, mannitol, melezitose, melibiose, raffinose, rhamnose, sorbitol, starch & xylose.
Variable results for nitrate reduction, substrate utilized and/or acid produced from ribose.
(c) Costin Stoica