In this article, we will explore and analyze the impact of Korarchaeota in different contexts and scopes. Since its emergence, Korarchaeota has generated a series of debates and controversies that have permeated various social and cultural spheres. Throughout history, Korarchaeota has left an indelible mark on people's lives, their thoughts and their actions. We will delve into the most relevant aspects, examining how Korarchaeota has shaped and transformed the world we inhabit, as well as the multiple interpretations it has given rise to. This article seeks to offer a broad and multidisciplinary perspective on Korarchaeota, inviting the reader to reflect on its meaning and influence on current society.
Proposed phylum within the Archaea
Korarchaeota
Scanning electron micrograph of the Obsidian Pool enrichment culture, showing Korarchaeota.
The Korarchaeota is a proposed phylum within the Archaea. The name is derived from the Greek noun koros or kore, meaning young man or young woman, and the Greek adjective archaios which means ancient. They are also known as Xenarchaeota. The name is equivalent to Candidatus Korarchaeota, and they go by the name Xenarchaeota or Xenarchaea as well.
Taxonomy
The Korarchaeota are a proposed phylum in the domain, Archaea. They are thought to have diverged relatively early in the genesis of Archaea and are among the deep-branching lineages. Korarchaeota are also known as Xenarchaeota. Korarchaeaota, along with Thaumarchaeota, Aigarchaeota, Crenarchaeota, belong to the superphylum called TACK. The evolutionary link between Asgard archaea and Korarchaeota of TACK (Thaumarchaeota, Aigarchaeota, Crenarchaeota, Korarchaeota) is yet unknown.
The first member of Korarchaeota to have its genome reconstructed was Korarchaeum crypotfilum, which was found in a hot spring in Yellowstone National Park and described in 2008. Since then only a few Korarchaeal genomes have been described. To check for Korarchaeota, samples from a variety of hot springs in Iceland and Kamchatka were gathered. According to the samples and analysis, the Icelandic samples contained about 87 distinct 16S ribosomal nucleic acid sequences, whereas the Kamchatkan samples contained about 33.
Based on protein sequences and phylogenetic analysis of conserved single genes, the Korarchaeote was identified as a “deep archaeal lineage” with a possible relationship to the Crenarchaeota. Furthermore, given the known genetic makeup of archaea, the Korarchaeota may have preserved a set of biological traits that correspond to the earliest known archaeal form.
Analysis of their 16S rRNA gene sequences suggests that they are a deeply branching lineage that does not belong to the main archaeal groups, Thermoproteota and Euryarchaeota. Analysis of the genome of one korarchaeote that was enriched from a mixed culture revealed a number of both Crenarchaeota- and Euryarchaeota-like features and supports the hypothesis of a deep-branching ancestry.
Listed below are the known species of Korarcheota Candidatus Korarchaeota
Genus Candidatus Korarchaeota archaeon
Genus Candidatus Korarchaeota archaeon NZ13-K
Genus Candidatus Korarchaeum
Species Candidatus Korarchaeum cryptofilum
Candidatus Korarchaeum cryptofilum OPF8
Genus Candidatus Methanodesulfokores
Species Candidatus Methanodesulfokores washburnensis
Genus Korarchaeote SRI-306
Genus environmental samples
uncultured korarchaeote pBA5
uncultured korarchaeote pJP27
uncultured korarchaeote pJP78
Reference species
A strain of Korarchaeum cryptofilum was cultivated from an enrichment culture from a hot spring in Yellowstone National Park, USA and described in 2008. The cells are long and needle-shaped, which gave the species its name, alluding to its "cryptical filaments". This organism lacks the genes for purinenucleotide biosynthesis and thus relies on environmental sources to meet its purine requirements.
Characteristics
Korarchaeota are a proposed phylum within the domain, Archaea, and therefore exhibit characteristics such as having a cell wall without peptidoglycan, as well as lipid membranes that are ether-linked. They have a surface layer of paracrystalline protein. This surface layer, known as the S-layer, is densely packed and consists of 1-2 proteins form various lattice structures and are most likely what maintains the cells’ structural integrity. They are typically rod-shaped, however, it has been found that this morphology can change to be thicker-shaped in the presence of higher sodium dodecyl sulfate (SDS) concentrations. Korarchaeota cells have an ultrathin filamentous morphology that may vary in length. They typically average 15 μm in length and 0.16 μm in diameter but can be seen up to 100 μm long. Some Archaea can fix carbon dioxide through the 3-hydroxypropionate/4-hydroxybutyrate pathway into organic compounds
Ecology
Korarcheota have only been found in hydrothermal environments ranging from terrestrial, including hot springs to marine, including shallow hydrothermal vents and deep-sea hydrothermal vents. Previous research has shown greater diversity of Korarchaea found in terrestrial hot springs compared to marine environments. Korarchaeota have been found in nature in only low abundances. Korarcheota likely originated in marine environments and then adapted to terrestrial ones.
Geographically, Korarcheota have been found in a variety of locations around the world including Japan, Yellowstone National Park, the Gulf of California, Iceland and Russia.
Korarchaeota are thermophiles, having been found living in conditions of up to 128 degrees Celsius. The lowest temperature they have been found in is 52 degrees Celsius. While they have frequently been observed living in acidic conditions, they have also been found living in conditions up to a pH of 10.
Researchers have identified a virus that can potentially infect Korarcheota.
^ abMcKay LJ, Dlakić M, Fields MW, Delmont TO, Eren AM, Jay ZJ, et al. (April 2019). "Co-occurring genomic capacity for anaerobic methane and dissimilatory sulfur metabolisms discovered in the Korarchaeota". Nature Microbiology. 4 (4): 614–622. doi:10.1038/s41564-019-0362-4. OSTI1779059. PMID30833730. S2CID256705892.
^ abAuchtung TA, Shyndriayeva G, Cavanaugh CM (January 2011). "16S rRNA phylogenetic analysis and quantification of Korarchaeota indigenous to the hot springs of Kamchatka, Russia". Extremophiles. 15 (1): 105–116. doi:10.1007/s00792-010-0340-5. PMID21153671. S2CID12091232.
^Liu Y, Brandt D, Ishino S, Ishino Y, Koonin EV, Kalinowski J, et al. (June 2019). "New archaeal viruses discovered by metagenomic analysis of viral communities in enrichment cultures". Environmental Microbiology. 21 (6): 2002–2014. doi:10.1111/1462-2920.14479. PMID30451355. S2CID53950297.
Further reading
Stackebrandt E, Frederiksen W, Garrity GM, Grimont PA, Kämpfer P, Maiden MC, et al. (May 2002). "Report of the ad hoc committee for the re-evaluation of the species definition in bacteriology". International Journal of Systematic and Evolutionary Microbiology. 52 (Pt 3): 1043–1047. doi:10.1099/ijs.0.02360-0. PMID12054223.
Gürtler V, Mayall BC (January 2001). "Genomic approaches to typing, taxonomy and evolution of bacterial isolates". International Journal of Systematic and Evolutionary Microbiology. 51 (Pt 1): 3–16. doi:10.1099/00207713-51-1-3. PMID11211268.
Young JM (May 2001). "Implications of alternative classifications and horizontal gene transfer for bacterial taxonomy". International Journal of Systematic and Evolutionary Microbiology. 51 (Pt 3): 945–953. doi:10.1099/00207713-51-3-945. PMID11411719.
Winker S, Woese CR (1991). "A definition of the domains Archaea, Bacteria and Eucarya in terms of small subunit ribosomal RNA characteristics". Systematic and Applied Microbiology. 14 (4): 305–310. doi:10.1016/s0723-2020(11)80303-6. PMID11540071.
Achenbach-Richter L, Woese CR (1988). "The ribosomal gene spacer region in archaebacteria". Systematic and Applied Microbiology. 10 (3): 211–214. doi:10.1016/s0723-2020(88)80002-x. PMID11542149.
McGill TJ, Jurka J, Sobieski JM, Pickett MH, Woese CR, Fox GE (1986). "Characteristic archaebacterial 16S rRNA oligonucleotides". Systematic and Applied Microbiology. 7 (2–3): 194–197. doi:10.1016/S0723-2020(86)80005-4. PMID11542064.
Woese CR, Gupta R, Hahn CM, Zillig W, Tu J (1984). "The phylogenetic relationships of three sulfur dependent archaebacteria". Systematic and Applied Microbiology. 5: 97–105. doi:10.1016/S0723-2020(84)80054-5. PMID11541975.