Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Taxonomy

The family Thermoanaerobacteraceae (Wiegel 2009) encompasses the genera Ammonifex, Brockia, Caldanaerobacter, Caldanaerobius, Caloribacterium, Carboxydothermus, Desulfovirgula, Gelria, Moorella, Tepidanaerobacter, Thermacetogenium, Thermanaeromonas, and the type genus Thermoanaerobacter. The genus list of Euzeby (http://www.bacterio.net/) lists a few more genera though the type species were transferred to other genera; as the taxa were validly published, they did keep their taxonomic status: Acetogenium kivui was reclassified as Thermoanaerobacter kivui (Collins et al. 1994), Carboxydibrachium pacificum as Caldanaerobacter subterraneus subsp. pacificus (Fardeau et al. 2004), Thermoanaerobium acetigenum as Caldicellulosiruptor acetigenus (Onyenwoke et al. 2006), Thermoanaerobium brockii as Thermoanaerobacter brockii subsp. brockii (Lee et al. 1993), and species of Thermobacteroides to Thermoanaerobacter (Rainey and Stackebrandt 1993), Clostridium (Fardeau et al. 2001), and Coprothermobacter (Rainey and Stackebrandt 1993).

The last comprehensive coverage of the family Thermoanaerobacteraceae has been presented by 2009 in Bergey’s Manual of Systematic Bacteriology, 2nd ed (Wiegel 2009), covering descriptions since 2006. Since then, new genera and new species of genera described until 2006 were proposed. This communication concentrates on recently described genera and species, and the reader should consult the chapter of 2009 for obtaining a more comprehensive overview of the biology of family members. Table 32.1 is a list of species belonging to genera described until 2006, together with some of the salient feature of these taxa. Table 32.2 compiles recently described genera of Thermoanaerobacteraceae.

Table 32.1 Species published since 2006, for genera described before 2006
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Table 32.2 New genera of Thermoanaerobacteraceae and their species, described since 2006
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The family contains anaerobic, mainly heterotrophic, but also chemolithoautotrophic members. Cells are mainly Gram positive, rod shaped, and spore forming, though same species stain Gram negatively, while no spores have been reported for other species. The family is phylogenetically heterogeneous, forming individual clades which are related to other families according to the ML tree (Fig. 32.1). The heterogeneity has been observed by Sekiguchi et al. (2006), while other species description exclusively included members of the family as reference strains in depicting phylogenetic dendrograms. Thermoanaerobacter and Caldanaerobacter are closely related and group adjacent to a clade consisting of Coprothermobacter, Dictyoglomus, and other Thermoanaerobacteraceae members such as Ammonifex, Tepidanaerobacter, and Brockia. Desulfovirgula and Thermanaeromonas form a third clade. A forth clade is phylogenetically heterogeneous in itself as it embraces authentic clostridia, symbiotic and synthrophic taxa, Heliobacteriaceae and Peptococcaceae, as well as the Thermoanaerobacteraceae members Caldanaerobius, Caloribacterium, Symbiobacterium, Gelria, and Moorella. Syntrophaceticus schinkii and Symbiobacterium thermophilum, not reported to be members of Thermoanaerobacteraceae, cluster closely with Thermacetogenium schinkii and Gelria glutamica, respectively. A fifth clade consists of Carboxydothermus. This family is certainly in need of a taxonomic revision.

Fig. 32.1
figure 1figure 1

Neighbor-joining genealogy reconstruction based on the RAxML algorithm (Stamatakis 2006) of the sequences of members of the family Thermoanaerobacteraceae and some neighboring taxa present in the LTP_106 (Yarza et al. 2010). The tree was reconstructed by using a subset of sequences. Representative sequences from closely relative genera were used to stabilize the tree topology. In addition, a 40 % maximum frequency filter was applied to remove hypervariable positions from the alignment. Scale bar indicates estimated sequence divergence

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Genome Sequences

Several representatives of Thermoanaerobacteraceae, especially from the type genus, were subjected to the analysis of genome sequences. Only a few examples of published or deposited sequences of strains of the various genera are given in Table 32.3. More information is available in the GOLD database (genomes.org/cgi-bib/Gold/Search.cgi).

Table 32.3 Examples of complete, incomplete, and draft genome sequences of Thermoanaerobacteraceae members as listed in the GOLD genome database
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