Deinococcus-Thermus

The Deinococcus-Thermus are a small group of bacteria that are highly resistant to environmental hazards.

There are two main groups.

• The Deinococcales include two families, with three genera, Deinococcus and Truepera, the former with several species that are resistant to radiation; they have become famous for their ability to eat nuclear waste and other toxic materials, survive in the vacuum of space and survive extremes of heat and cold.
• The Thermales include several genera resistant to heat (Marinithermus, Meiothermus, Oceanithermus, Thermus, Vulcanithermus). Thermus aquaticus was important in the development of the polymerase chain reaction where repeated cycles of heating DNA to near boiling make it advantageous to use a thermo-stable DNA polymerase enzyme.

Though these two groups evolved from a common ancestor, the two mechanisms of resistance appear to be largely independent.

These bacteria have thick cell walls that give them gram-positive stains, but they include a second membrane and so are closer in structure to those of gram-negative bacteria.

Cavalier-Smith calls this clade Hadobacteria (from Hades, the Greek underworld).

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 111 by 'The All-Species Living Tree' Project

Note:
â™  Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LSPN)

Sequenced genomes

Currently there are 10 sequenced genomes of strains in this phylum.

• Deinococcus radiodurans R1
• Thermus thermophilus HB27
• Thermus thermophilus HB8
• Deinococcus geothermalis DSM 11300
• Deinococcus deserti VCD115
• Meiothermus ruber DSM 1279
• Meiothermus silvanus DSM 9946
• Truepera radiovictrix DSM 17093
• Oceanithermus profundus DSM 14977

The two Meiothermus species were sequenced under the auspices of the Genomic Encyclopedia of Bacteria and Archaea project (GEBA), which aims at sequencing organisms based on phylogenetic novelty and not on pathologenicity or notoriety. Currently, the genome of Thermus aquaticus Y51MC23 is in the final stages of assembly by the DOE Joint Genome Institute

References

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