From Wikipedia, the free encyclopedia

Crenarchaeota
Scientific classification
Kingdom: Archaea Phylum: Crenarchaeota Cavalier-Smith 2002
Class
Thermoprotei

The phylum Crenarchaeota (or Crenarchaea, also known as eocytes), is a member of the Archaea domain. Initially, the Crenarchaeota were thought to be extremeophiles (e.g., thermophilic and psychrophilic organisms) but recent studies have identified them as the most abundant archaea in the marine environment.^[1] Originally, they were separated from the other archaea based on rRNA sequences; since then physiological features, such as lack of histones have supported this division. However, some crenarchaea were found to have histones.^[2] Until recently all cultured Crenarchaea had been thermophilic or hyperthermophilic organisms, some of which have the ability to grow up to 113 °C.^[3] These organisms stain gram negative and are morphologically diverse having rod, cocci, filamentous and oddly shaped cells.^[4]

One of the best characterized members of the Crenarcheota is Sulfolobus solfataricus. This organism was originally isolated from geothermally-heated sulfuric springs in Italy, and grows at 80 °C and pH of 2-4.^[5] Since its initial characterization by Wolfram Zillig, a pioneer in thermophile and archaeon research, similar species in the same genus have been found around the world. Unlike the vast majority of cultured thermophiles, Sulfolobus grows aerobically and chemoorganotrophically (gaining its energy from organic sources such as sugars) . These factors allow a much easier growth than anaerobic organisms and have led to Sulfolobus becoming a model organism for the study of hyperthermophiles and a large group of diverse viruses that replicate within them.

Beginning in 1992, data were published that reported sequences of genes belonging to the Crenarchaea in marine environments.^[6],[7] Since then analysis of the abundance lipids from the membranes of Crenarchaea taken from the open ocean have been used to determine the concentration of these “low temperature Crenarchaea.” Based on these measurements these organisms are thought to be very abundant and one of the main contributors to the fixation of carbon. DNA sequences from Crenarchaea have also been found in soil and freshwater environments suggesting that this phylum is ubiquitous to most environments.^[8]

In 2006, evidence of the first cultured “low temperature Crenarchaea” was published. Named Nitrosopumilus maritimus, it is an ammonia-oxidizing organism isolated from a marine aquarium tank and grown at 28 °C.^[9]

1. ^ Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1. 
2. ^ Cubonova L, Sandman K, Hallam SJ, Delong EF, Reeve JN (2005). "Histones in crenarchaea". Journal of Bacteriology 187 (15): 5482-5485. PubMed. 
3. ^ Blochl E, Rachel R, Burggraf S, Hafenbradl D, Jannasch HW, Stetter KO (1997). "Pyrolobus fumarii, gen. and sp. nov., represents a novel group of archaea, extending the upper temperature limit for life to 113 °C". Extremophiles 1 (1): 14-21. PubMed. 
4. ^ Garrity GM, Boone DR (editors) (2001). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the Deeply Branching and Phototrophic Bacteria, 2nd, Springer. ISBN 0-387-98771-1. 
5. ^ Zillig W, Stetter KO, Wunderl S, Schulz W, Priess H, Scholz I (1980). "The Sulfolobus-"Caldariellard" group: Taxonomy on the basis of the structure of DNA-dependent RNA polymerases". Arch. Microbiol. 125: 259–269. 
6. ^ DeLong EF (1992). "Archaea in coastal marine environments". Proc Natl Acad Sci U S A 89 (12): 5685-9. PubMed fulltext. 
7. ^ Fuhrman JA, McCallum K, Davis AA (1993). "Phylogenetic diversity of subsurface marine microbial communities from the Atlantic and Pacific Oceans". Appl Environ Microbiol 59 (5): 1294-302. PubMed. 
8. ^ Barns SM, Delwiche CF, Palmer JD, Pace NR (1996). "Perspectives on archaeal diversity, thermophily and monophyly from environmental rRNA sequences". Proc Natl Acad Sci U S A 93 (17): 9188-93. PubMed. 
9. ^ Ingalls AE, Shah SR, Hansman RL, Aluwihare LI, Santos GM, Druffel ER, Pearson A (2006). "From the Cover: Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon". Proc Natl Acad Sci U S A 103 (17): 6442-7. PubMed abstract. 

• Crenarchaeota at the Tree of Life
• Crenarchaeota from the University of Wisconsin Virtual Microbiology site.
• NCBI taxonomy page for Crenarchaeota
• LSPN page for Crenarchaeota