Deinococcota (synonym, "Deinococcus-Thermus") is a phylum of bacteria with a single class, Deinococci (from Ancient Greek δεινός (deinós), meaning "terrible", and κόκκος (kókkos), meaning "berry"), that are highly resistant to environmental hazards, also known as extremophiles.

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.

Taxonomy

The phylum Deinococcota consists of a single class (Deinococci) and two orders:

  • The Deinococcales include two families (Deinococcaceae and Trueperaceae), with three genera, Deinococcus, Deinobacterium and Truepera. Truepera radiovictrix is the earliest diverging member of the order. The genus includes 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, Rhabdothermus) placed within a single family, Thermaceae. Phylogenetic analyses demonstrate that within the Thermales, Meiothermus and Thermus species form a monophyletic cluster, with respect to Marinithermus, Oceanithermus, Vulcanithermus and Rhabdothermus that branch as outgroups within the order.

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

Molecular signatures

Molecular signatures in the form of conserved signature indels (CSIs) and proteins (CSPs) have been found that are uniquely shared by all members belonging to the Deinococcota phylum. while those found in Excinuclease ABC, DNA gyrase, and DNA repair protein RadA in Deinococcales species may be associated with radioresistance.

Additionally, some genera within this group, including Deinococcus, Thermus, and Meiothermus, also have molecular signatures that demarcate them as individual genera, inclusive of their respective species, providing a means to distinguish them from the rest of the group and all other bacteria.

! colspan=1 | 120 marker proteins based GTDB release 10-RS226

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Taxonomy

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)

  • Phylum Deinococcota <small>Oren and Garrity 2021</small>
  • Class Deinococci <small>Garrity & Holt 2002</small> ["Deinococcia" <small>Oren, Parte & Garrity 2016 ex Cavalier-Smith 2020</small>; "Thermi" <small>Rinke et al. 2013</small>; "Thermia" <small>Cavalier-Smith 2020</small>]
  • Order Deinococcales <small>Rainey et al. 1997</small> [Trueperales <small>García-López et al. 2020</small>]
  • Family Deinococcaceae <small>Brooks and Murray 1981 emend. Rainey et al. 1997</small>
  • Genus Deinococcus <small>Brooks and Murray 1981 emend. Rainey et al. 1997</small>
  • Genus Deinobacterium <small>Ekman et al. 2011</small>
  • Family Trueperaceae <small>Rainey et al. 2005</small>
  • Genus Truepera <small>da Costa, Rainey and Albuquerque 2005</small>
  • Order Thermales <small>Rainey and Da Costa 2002</small>
  • Family Thermaceae <small>Da Costa and Rainey 2002</small>
  • Genus Allomeiothermus <small>Jiao et al. 2023</small>
  • Genus Calidithermus <small>Raposo et al. 2019</small>
  • Genus Marinithermus <small>Sako et al. 2003</small>
  • Genus Meiothermus <small>Nobre et al. 1996 emend. Albuquerque et al. 2009</small>
  • Genus Oceanithermus <small>Miroshnichenko et al. 2003 emend. Mori et al. 2004</small>
  • Genus Rhabdothermus <small>Steinsbu et al. 2011</small>
  • Genus Thermus <small>Brock and Freeze 1969 emend. Nobre et al. 1996</small>
  • Genus Vulcanithermus <small>Miroshnichenko et al. 2003</small>

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 pathogenicity or notoriety.

See also

  • List of bacteria genera
  • List of bacterial orders

References