Clostridiaceae
Encyclopedia
The Clostridiaceae are a family of the Clostridia
, and contains the Clostridium
genus.
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,
Acidaminobacter, Alkaliphilus, Anaerobacter, Caloramator, Caloranaerobacter, Coprobacillus, Dorea, Natronincola,
Oxobacter, Sarcina, Sporobacter, Thermobrachium, Thermohalobacter and Tindallia. The previous inclusion of these
additional genera in a family Clostridiaceae is based for the most part on the fact that the type species 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 taxonimic 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 the genus
Clostridium are in fact not closely related to the type species of the genus, C. butrycum, 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(1975), but it was the 16S rRNA gene sequence approach that revealed the
actual phylogenetic relationships between the species of this genus and other genera.
The genus Clostridium current comprises 152 validly described species in Nomenclature ( http://www.
bacterio.net ). However, on the basis of 16S rRNA gene sequence analyses, only 73 of these validly described species
fall within the radiation of the type species of the genus Clostridium.
Clostridia
The Clostridia are a 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...
, and contains the Clostridium
Clostridium
Clostridium is a genus of Gram-positive bacteria, belonging to the Firmicutes. They are obligate anaerobes capable of producing endospores. Individual cells are rod-shaped, which gives them their name, from the Greek kloster or spindle...
genus.
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,
Acidaminobacter, Alkaliphilus, Anaerobacter, Caloramator, Caloranaerobacter, Coprobacillus, Dorea, Natronincola,
Oxobacter, Sarcina, Sporobacter, Thermobrachium, Thermohalobacter and Tindallia. The previous inclusion of these
additional genera in a family Clostridiaceae is based for the most part on the fact that the type species 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 taxonimic 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 the genus
Clostridium are in fact not closely related to the type species of the genus, C. butrycum, 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(1975), but it was the 16S rRNA gene sequence approach that revealed the
actual phylogenetic relationships between the species of this genus and other genera.
The genus Clostridium current comprises 152 validly described species in Nomenclature ( http://www.
bacterio.net ). However, on the basis of 16S rRNA gene sequence analyses, only 73 of these validly described species
fall within the radiation of the type species of the genus Clostridium.