DOMAIN ARCHAEA – Diversity of Life

DESCRIPTION OF THE DOMAIN ARCHAEA (WOESE ET AL. 1990)

ARCHAEA

DOMAIN ARCHAEA LINKS

Archaea (pronouunced: ar-KE-a; sing. Archaeon) is a transliteration of the Greek noun ἀρχαῖα which means ancient ones.

INTRODUCTION

Barring viruses, living things seem to come in two different fundamental forms: prokaryotes and eukaryotes. The separation is based on cellular structure or ultrastructure and some aspects of biochemistry. However, the lineage of these two groups had been largely unexplored until Woese and Fox (1977) chose the 16-S rRNA subunit to sequence in an attempt to determine the relationships between different prokaryotes and eukaryotes. To the surprise of the scientific community, their results showed that life existed in three fundamental forms and two of them were prokaryotic. Woese called the three groups Domains and named them Archaea, Bacteria, and Eukarya. Within a common taxonomic hierarchy, then, kingdoms are clustered within domains.

Archaea is a domain of prokaryotic organisms that have a number of unique cellular features which serve to distinguish them from the Eubacteria, the other prokaryotic domain. They differ in the form and structure of their ribosomes , the type and linkage of their lipids, structure of the cell covering (e.g. they have no peptidoglycan), and a different type of RNA polymerase (Margulis and Schwartz 1998). The neat package of three domains fails, however, because lateral gene transfer (a “mechanism” that is quite common in the prokaryotes) mixes the DNA of unrelated taxa. Although small subunit rRNA nucleic acid is about the most conserved of the DNA sequences, with enough time, most lineages likely have become somewhat scrambled.

With that warning we offer the Woese et al. (1990) system of the Domain Archaea. This system was developed and popularized by Margulis and Schwartz (1998). We have incorporated modifications from Garrity et al. (2001 and 2003) and Black (2002). Thus, for the prokaryotes, we return to the two-domain system of Woese et al. (1990) rather than the two-phylum designations of Margulis and Schwartz (1998) and Garrity et al. (2001). So, the Domain Archaea in this system has two kingdoms: the Euryarchaeota and the Crenarchaeota (see Figure 1).

The domain is made of of taxa that are considered extremophiles. That is, they require environmental conditions that would kill most other forms of life. Many require very high temperatures and are poisoned by oxygen. All members of the Crenarchaeota are hyperthermophiles (growth maxima near the boiling point of water) and they metabolize sulfur compounds. Euryarcharota has taxa that resemble the Euryarchaeota in their environmental requirements (see Figure 1, Eurythermea clade). The other phyla in the Neobacteria clade do not seem to be thermophilic, but the methanogens are obligate anaerobes and utilize hydrogen gas, requirements that are met in waterlogged organic sediments in places like swamps and marshes. Halobacteria can tolerate and utilize oxygen, but live in environments that have very high ionic concentrations, like the Dead Sea and the Great Salt Lake. Taxa of this domain push the limits of what we consider the biosphere to be.

FIGURE 1. CLADOGRAM OF THE PHYLA OF THE ARCHAEA. The general organization of the cladogram according to The All-Species Living Tree Project (Yarza et al. 2008, 2010).

C = CRENARCHAEOTA

E = EURYARCHAEOTA

Eu = EURYTHERMEA

Ne = NEOBACTERIA

KINGDOMS OF THE ARCHAEA

CRENARCHAEA (Woese et al. 1990)
EURYARCHAEOTA (Woese et al. 1990)

FURTHER READING:

DISCOVERY OF THE DOMAINS OF LIFE

LITERATURE CITED

Black, J. G. 2002. Microbiology, Principles and Explorations. 5th ed. John Wiley and Sons, Inc. New York.

Gao, B. and R. S. Gupta. 2007. Phylogenetic analysis of proteins that are distinctive of Archaea and its main subgroups and the origin of methanogenesis. BMC Genomics. 8:86. http://www.biomedcentral.com/1471-2164/8/86.

Garrity, G. M., M. Winters, and D. Searles. 2001. Bergey’s manual of systematic bacteriology. 2nd ed. Springer-Verlag. New York.

Garrity, G. M., J. A. Bell, and T. G. Lilburn. 2003. Taxonomic Outline of the Prokaryotes. Bergey’s Manual of Systematic Bacteriology. 2nd edition. Release 4.0. Springer-Verlag. New York. pp. 1-397.

Margulis, L. and K. Schwartz. 1988. Five kingdoms, an illustrated guide to the phyla of life on earth. 2nd Edition. W. H. Freeman and Co. New York.

Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Co. New York.

Munoz, R., P. Yarza, W. Ludwig, J. Euzeby, R. Amann, K-H. Schleifer, F. O. Glöckner, and R. Rosello-Mora. 2011. Release LTPs 104 of the All-Species Living Tree. Systematic and Applied Microbiology 34: 169-170.

Woese, C. R. and G. E. Fox. 1977. Phylogenetic structure of the prokaryotic domain: the primary kingdoms. Proceedings of the National Academy of Sciences USA. 74:5088-5090.

Woese, C. R., O. Kandler, and M. L. Wheelis. 1990. Towards a natural system of organisms: Proposal for the domains Archaea, Bacteria, and Eucarya. Proc. Natl. Acad. Sci. USA. 87: 4576-4579.

Yarza, P., M. Richter, J. R. Peplies, J. Euzeby, R. Amann, H-H. Schleifer, W. Ludwig, F. O. Glöckner, and R. Rosello-Mora. 2008. The all-species living tree project: a 16S rRNA-based phylogenetic tree of all sequenced type strains. Systematic and Applied Microbiology. 31: 241-250.

Yarza, P., W. Ludwig, J. Euzeby, R. Amann, H-H. Schleifer, F. O. Glöckner, and R. Rosello-Mora. 2010. Update of the all-species living tree project based on 16S and 23S rRNA sequence analyses. Systematic and Applied Microbiology. 33: 291-299.

By Jack R. Holt. Last revised: 10/12/2021

DESCRIPTION OF THE DOMAIN ARCHAEA (WOESE ET AL. 1990)

Document Footer