The Deinococcus-Thermus are a small group of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 composed of cocci highly resistant to environmental hazards.

There are two main groups.

• The Deinococcales include two families, with three genera, Deinococcus
  Deinococcus
  The Deinococcus is the one genus of three of the Deinococcales group from the Deinococcus-Thermus phylum highly resistant to environmental hazards.There are 47 species of Deinococcus described according to NCBI on 25 august 2011 :...
  
  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
  Thermus aquaticus
  Thermus aquaticus is a species of bacterium that can tolerate high temperatures, one of several thermophilic bacteria that belong to the Deinococcus-Thermus group...
  
  was important in the development of the polymerase chain reaction
  Polymerase chain reaction
  The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
  
   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

Gram-positive

Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

 stains, but they include a second membrane and so are closer in structure to those of gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 bacteria.

Cavalier-Smith calls this clade Hadobacteria (from Hades

Hades

Hades , Hadēs, originally , Haidēs or , Aidēs , meaning "the unseen") was the ancient Greek god of the underworld. The genitive , Haidou, was an elision to denote locality: "[the house/dominion] of Hades". Eventually, the nominative came to designate the abode of the dead.In Greek mythology, Hades...

, the Greek

Ancient Greece

Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

 underworld).

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LSPN) and the phylogeny is based on 16S rRNA-based LTP release 106 by The All-Species Living Tree Project 
Note:

♠ Strains found at the National Center for Biotechnology Information

National Center for Biotechnology Information

The National Center for Biotechnology Information is part of the United States National Library of Medicine , a branch of the National Institutes of Health. The NCBI is located in Bethesda, Maryland and was founded in 1988 through legislation sponsored by Senator Claude Pepper...

 (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 sp. 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