Clostridia

Clostridia
Scientific classification
Kingdom:	Bacteria
Phylum:	Firmicutes
Class:	Clostridia
Orders
Clostridiales    Catabacteriaceae    Clostridiaceae    Eubacteriaceae    Graciibacteraceae    Heliobacteriaceae    Lachnospiraceae    Oscillospiraceae    Peptococcaceae    Peptostreptococcaceae    Ruminococcaceae    Syntrophomonadaceae    Veillonellaceae Halanaerobiales Thermoanaerobacteriales

The Clostridia (sulfite-reducing bacteria) are a highly polyphyletic class of Firmicutes, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the genus Clostridium are all Gram-positive and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future.

Most species of the genus Clostridium are saprophytic organisms found in many places in the environment, most notably the soil. However, the genus does contain some human pathogens (outlined below). The toxins produced by certain members of the Clostridium genus are among the most dangerous known to man. Examples are tetanus toxin (known as tetanospasmin) produced by C. tetani and botulinum toxin produced by C. botulinum.

Notable species of this class include:

• Clostridium perfringens (Gangrene, Food poisoning)
• Clostridium difficile (Pseudomembranous colitis)
• Clostridium tetani (Tetanus)
• Clostridium botulinum (Botulism)
• Clostridium acetobutylicum
• Clostridium haemolyticum
• Clostridium novyi
• Clostridium oedematiens

Heliobacteria are also members of the class Clostridia.

Some of the enzymes produced by this group are used in bioremediation.

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) and the phylogeny is based on 16S rRNA-based LTP release 106 by The All-Species Living Tree Project

Clostridia s.s.

Peptococcaceae 2 Peptococcaceae 1 Heliobacteriaceae Peptococcaceae 3 Thermincola   Negativicutes Acidaminococcaceae Veillonellaceae Peptococcaceae 4 Dethiobacter alkaliphilus Natranaerobiaceae Anaerobranca {Clostridiales Family XIV. Incertae Sedis} Eubacteriaceae Garciella nitratireducens Clostridiaceae 3 Clostridiales Family XI. Incertae Sedis [incl. Anaerosphaera aminiphila] Eubacterium angustum Proteiniborus ethanoligenes Clostridiaceae 4 [incl. various Clostridium ssp.] Clostridiales Family XII. Incertae Sedis Clostridiales Family XIII. Incertae Sedis [incl. various Eubacterium spp.] Clostridiaceae 2 [incl. various Clostridium ssp.] Peptostreptococcaceae [incl. Clostridiales Family XIX. Incertae Sedis and various Clostridium & Eubacterium spp.]   Clostridiales s.s. Thermoanaerobacterales Unnamed clade III [incl. Caldicoprobacter] Clostridiaceae 1 [incl. various Eubacterium spp.] Gracilibacter thermotolerans Lutispora thermophila Ruminococcaceae [incl. Bacteroides cellulosolvens, Butyricicoccus pullicaecorum, Gemmiger formicilis, Oscillibacter valericigenes, Saccharofermentans acetigenes and various Clostridium & Eubacterium spp.] Lachnospiraceae [incl. Anaerosporobacter mobilis, Desulfotomaculum guttoideum, Fusobacterium naviforme, Lactobacillus rogosae, Lactonifactor longoviformis, various Bacteroides, Clostridium, Eubacterium, & Ruminococcus ssp.]

See also

Clostridium