Sulfolobus

In taxonomy, Sulfolobus is a genus of the Sulfolobaceae.^[1]

Sulfolobus species grow in volcanic springs with optimal growth occurring at pH 2-3 and temperatures of 75-80 °C, making them acidophiles and thermophiles respectively. Sulfolobus cells are irregularly shaped and flagellar.

Sulfolobus species are generally named after the location from which they were first isolated, e.g. Sulfolobus Solfataricus was first isolated in the Solfatara (volcano). Other species can be found throughout the world in areas of volcanic or geothermal activity, such as geological formations called mud pots, which are also known as solfatara (plural of solfatare).

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Sulfolobus as a model to study the molecular mechanisms of DNA replication

As the first Archaeal genome, Methanococcus jannaschii , has been sequenced completely, in 1996, it was found that the genes in the genome of Methanococcus jannaschii involved in DNA replication, transcription, translation, were more related to those counterparts in Eukaryote than in Bacteria. In 2001, the first genome sequence of Sulfolobus , Sulfolobus solfataricus P2, was published. In P2's genome, the genes related to chromosome replication were found to be more related to Eukaryote's. These genes include DNA polymerase, primase (including two subunits), MCM, CDC6/ORC1, RPA, RPC, PCNA. In 2004, the origins of DNA replication of Sulfolobus solfataricus and Sulfolobus acidocaldarius were identified. It showed that both species contained 3 origins in their genome. This is the first time that more than a single origin of DNA replication has been shown to be used in a prokaryotic cell. The mechanism of DNA replication in archaea is evolutionary conserved, and similar to that of Eukaryotes. Sulfolobus is now used as a model to study the molecular mechanisms of DNA replication in Archaea. And because the system of DNA replication in Archaea is much simpler than that in Eukarote, it was suggested that Archaea could be used as model to study the much more complexed DNA replication in Eukaryote.

Role in biotechnology

Sulfolobus proteins are of interest for biotechnology and industrial use due to their thermostable nature. Intracellular proteins are not necessarily stable at low pH however, as Sulfolobus species maintain a significant pH gradient across the outer membrane. Like all Crenarchaeota, they are metabolically dependent on sulfur: heterotrophic or autotrophic, their energy comes from the oxidation of sulfur and/or cellular respiration in which sulfur acts as the final electron acceptor. For example, S. tokodaii is known to oxidize hydrogen sulfide to sulfate intracellularly.

Sulfolobus as a viral host

Lysogenic viruses infect Sulfolobus for protection. The viruses cannot survive in the extremely acidic and hot conditions that Sulfolobus lives in, and so the viruses use Sulfolobus as protection against the harsh elements. This relationship allows the virus to replicate inside the archaea without being destroyed by the environment.

Genome status

The complete genomes have been sequenced for S. acidocaldarius DSM 639 (2,225,959 nucleotides), S. solfataricus P2 (2,992,245 nucleotides), and S. tokodaii str. 7 (2,694,756 nucleotides).

References

• Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1. 

Further reading

Scientific journals

• Judicial Commision of the International Committee on Systematics of Prokaryotes (2005). "The nomenclatural types of the orders Acholeplasmatales, Halanaerobiales, Halobacteriales, Methanobacteriales, Methanococcales, Methanomicrobiales, Planctomycetales, Prochlorales, Sulfolobales, Thermococcales, Thermoproteales and Verrucomicrobiales are the genera Acholeplasma, Halanaerobium, Halobacterium, Methanobacterium, Methanococcus, Methanomicrobium, Planctomyces, Prochloron, Sulfolobus, Thermococcus, Thermoproteus and Verrucomicrobium, respectively. Opinion 79". Int. J. Syst. Evol. Microbiol. 55: 517–518. PMID 15653928.

• Brock TD, Brock KM, Belly RT, Weiss RL (1972). "Sulfolobus: a new genus of sulfur-oxidizing bacteria living at low pH and high temperature". Arch. Mikrobiol. 84: 54–68. PMID 4559703.

Scientific books

• Stetter, KO (1989). "Order III. Sulfolobales ord. nov. Family Sulfolobaceae fam. nov.", in JT Staley, MP Bryant, N Pfennig, and JG Holt, eds.: Bergey's Manual of Systematic Bacteriology, Volume 3, 1st ed., Baltimore: The Williams & Wilkins Co., p. 169. 

Scientific databases

• PubMed references for Sulfolobus

• PubMed Central references for Sulfolobus

• Google Scholar references for Sulfolobus

• NCBI taxonomy page for Sulfolobus
• Search Tree of Life taxonomy pages for Sulfolobus
• Search Species2000 page for Sulfolobus
• MicrobeWiki page for Sulfolobus
• LSPN page for Sulfolobus

• Comparative Analysis of Sulfolobus Genomes (at DOE's IMG system)

• Sulfolobus Genome Projects (from Genomes OnLine Database)