DESCRIPTION OF THE KINGDOM CRENARCHAEA AND ITS SINGLE PHYLUM CRENARCHAEOTA (BOTH DEFINED BY WOESE ET AL. 1990)
| ARCHAEA> CRENARCHAEA> CRENARCHAEOTA |
KINGDOM CRENARCHAEA LINKS
| INTRODUCTION TO THE KINGDOM CRENARCHAEA AND ITS SINGLE PHYLUM CRENARCHAEOTA In general, these are the hyperthermophiles, and they include organisms that grow best at very high temperatures (approaching the boiling point of water) and in the presence of sulfur from which they derive energy. Both sulfur metabolism and growth maxima in extremely high temperatures likely are primitive characters and may provide insight into the earliest organisms on earth. Despite their extreme physiology and environmental requirements, these organisms have typical microbial forms (see Figures 1 and 2). Environments that are very hot and rich in sulfur are associated with geothermal sites (geothermally heated soils and surface hot springs; see Figure 3). Crenarchaeans are the producers that form the foundation of the productive deep ocean geothermal vent environments, called sulfotara (text with tooltip) Solfatara are environments that have elevated temperatures and are rich in sulfur compounds. Examples are deep ocean vents and hot volcanic springs. . This is a problematic group of Archaea (indeed, almost all Archaea are problematic). Although, fundamental synapomorphies do not seem to have been defined for the Crenarchaeota, the group seems to be well supported by 16S rRNA sequence trees. Mindful of that, we have followed the system of Garrity et al. (2001 and 2003) for this kingdom/phylum. Still, we recognize that the group as it is defined likely is paraphyletic. This group has undergone extensive revision since 1977. Margulis and Schwartz (1998) lump the all thermoacidophils together into a taxon called Crenarchaeota which we treat as a kingdom. We have separated the groups because they are clearly different in 16S rRNA studies where Thermoplasma and the extreme halophiles appear to be much more closely allied to the Methanobacteria. Garrity et al. (2001) and Margulis and Schwartz (1998) consider the taxon to be a phylum within the Domain Archaea. The All-Species Living Tree Project (Yarza et al. 2008 and 2010, simplified in Figure 4) shows the Crenarchaea as a sister to the other archaean taxa. We have followed the general organization of the whole domain as defined by Garrity et al. (2001 and 2003) in that we include only the taxa in the Class Thermoprotei as defined by Garrity et al. (2001 and 2003). |
 |  |  |
| FIGURE 1. A TEM micrograph of Thermoproteus. Image from http://hanskrause.de/HKHPE/hkhpe_02_06.htm | FIGURE 2. A TEM micrograph of Sulfolobus. Image from http://web.pdx.edu/~kstedman/research.html | FIGURE 3. A hot sulfur spring in Yellowstone National Park, an environment in which Sulfolobus thrives. Image from the National Park Service, in the Public Domain |
FIGURE 4. A Cladogram that shows the relationships between the major clades of the Archaea. Thermoprotei, the single phylum of the Crenarchaea.
C = CRENARCHAEOTA
E = EURYARCHAEOTA
Eu = EURYTHERMEA
Ne = NEOBACTERIA
| 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. 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: 02/11/2013 |
