Clostridium botulinum

Clostridia refers to a class of predominantly gram-positive, anaerobic to aero -tolerant endosporenbildenden bacteria. The class is defined exclusively by the sequence analysis of the 16S rRNA. With respect to morphology, physiology, ecology and cell wall chemistry is extremely diverse and has no autapomorphies over the other Firmicutes on; it includes, for example, in addition to gram-positive and gram- negative genera.

The class was proposed in 2005 in Volume 2 of the second edition of Bergey's Manual of Systematic Bacteriology, but described in Volume 3 in 2009 and 2010 on the Validation List of the International Journal of Systematic and Evolutionary Microbiology ( IJSEM ) in accordance with the requirements of the International Code of Nomenclature of Bacteria valid published. Next to the most species-rich order Clostridiales It also includes orders Halanaerobiales, Natranaerobiales ( single family: Natranaerobiaceae ) and Thermoanaerobacteriales and some so far unidentified isolates classified.

List of orders and families

According to the List of Prokaryotic names with Standing in Nomenclature ( LPSN ) the class includes the following orders and families:

  • Order Clostridiales Prévot 1953 Caldicoprobacteraceae Yokoyama et al. 2010
  • Clostridiaceae Pribram 1933 Clostridia ( Clostridium Prazmowski 1880) and 20 additional genera
  • Halanaerobiaceae Corrig. Oren et al. 1984
  • Halobacteroidaceae Zhilina & Rainey 1995
  • Natranaerobiaceae Mesbah et al. 2007
  • Thermoanaerobacteriaceae
  • Thermodesulfobiaceae Mori et al. 2004

In uncertain position within the class Epulopiscium is fishelsoni, a very large, polyploid species of bacteria.



  • Firmicutes (Department)
  • Firmicutes