The Clostridiaceae are a family of the
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
l class
Clostridia
The Clostridia are a highly polyphyletic class of Bacillota, 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. S ...
, and contain the genus ''
Clostridium''.
The family Clostridiaceae (scientific name) defined by the taxonomic outline of '' Bergey's Manual of Systematic Bacteriology '' contains as its core the genus ''
Clostridium'' (''sensu stricto''), as well as ''
Acetivibrio
''Acetivibrio'' is a genus of Clostridia
The Clostridia are a highly polyphyletic class of Bacillota, including ''Clostridium'' and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are oblig ...
'', ''
Acidaminobacter'', ''
Alkaliphilus'', ''
Anaerobacter'', ''
Caloramator'', ''
Caloranaerobacter'', ''
Coprobacillus'', ''
Dorea'', ''
Natronincola'', ''
Oxobacter'', ''
Sarcina
The ''sarcina'' was the marching pack carried by Roman legionaries, the heavy infantry of the Roman legions.
Most of a legionary's equipment other than his arms and armour would, in early times, have been consigned to a baggage train and b ...
'', ''
Sporobacter'', ''
Thermobrachium'', ''
Thermohalobacter'', and ''
Tindallia''. The previous inclusion of these additional genera (as seen on the right) in a family Clostridiaceae is based for the most part because the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...
of these genera are in many cases phylogenetically related to misclassified species of the genus ''Clostridium''. However, with the exception of ''Anaerobacter'', ''Caloramator'', ''Oxobacter'', ''Sarcina'', and ''Thermobrachium'', these genera fall outside the radiation of what can be considered the true family Clostridiaceae and are now regarded as belonging to other families within the low G + C, Gram-positive phylum.
This misclassification is the result of well-known problems of the current taxonomic structure of the
traditional genus ''Clostridium''. The phylogenetic analysis of Collins (1994) was the first large-scale comparison of 16S rRNA gene sequences of species of the genus ''Clostridium'' and related taxa. The fact that the species of the genus ''Clostridium'' did not form a monophyletic group has been shown in a number of studies in which small groups of ''Clostridium'' species had been compared as far back as 1981. The comparative study of Collins (1994) and subsequent studies can be used to conclude that more than half of the species currently assigned to this genus are in fact not closely related to the type species, ''
C. butyricum'', and from a phylogenetic standpoint should not be included in a newly defined genus ''Clostridium''.
This extensive genetic diversity of the genus ''Clostridium'' had been shown using 23S rRNA:DNA hybridization studies back in 1975 by Johnson and Francis, but the 16S rRNA gene sequence approach revealed the actual phylogenetic relationships between the species of this genus and other genera.
The genus ''Clostridium'' currently comprises 152 validly described species in nomenclature.
www.bacterio.net
/ref> However, on the basis of 16S rRNA gene sequence analyses, only 73 of these fall within the radiation of the type species of the genus ''Clostridium''.
Subdivisions
The polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
family Clostridiaceae comprises the following:
See also
* List of bacteria genera
* List of bacterial orders
References
{{Taxonbar, from=Q592153