Sulfolobus tokodaii strain 7

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A Microbial Biorealm page on the genus Sulfolobus tokodaii strain 7


Archaea,; Crenarchaeota; Thermoprotei; Sulfolobales; Sulfolobaceae; Sulfolobus; Sulfolobus tokodaii (8).

Description and significance

The strain was isolated in 1983 from Beppu hot springs in Kyusyu, Japan by Dr. Tairo Oshima and his colleagues. S. tokodaii strain 7 grows optimally in acidic, sulfur-rich environments at 80 degrees Celsius. Sulfolobus tokodaii strain 7 has not been identified as a pathogen. However, because this microorganism inhabits such an extreme environment, it is significant because it can be used to study the thermostability of proteins (5). S. tokodaii strain 7 has also been used to oxidize the sulfur that is created by pollution that causes toxicity and acidification of water and rain in the environment (4).

Genome structure

The complete genomic sequence of S. tokodaii strain 7 has been determined. The genomic size is 2,694,756 base pairs long and has a GC content of 32.8%. The chromosome is circular and sequence comparison suggests the integration of a plasmid from an ancestral species, which would explain the larger size of the genome in this strain. Within the genome 2826 potential protein-coding regions along with one 16S-23S rRNA cluster, one 5S rRNA gene and 46 tRNA genes have been identified (3).

Cell structure, metabolism & life cycle

The cells of S. tokodaii strain 7 are irregular cocci and vary in size from roughly 0.5 to 0.8 micrometers in diameter. They have flattened and uneven surfaces, and the colonies are plate tan with entire margins, translucent, smooth and convex. Atomic force microscope image of S. tokodaii strain 7 (6). S, tokodaii strain 7 grows chemoheterotrophically under obligatory aerobic conditions. The structure of an archaea cell envelope differs from that of a bacterial cell wall in that archaea only have one membrane, and are covered by a paracrystilline protein layer (1). Growth occurs between 70 and 85 degrees Celsius, but growth will only be optimal at 80°C under aerobic and chemoheterotrophic conditions. No growth can be detected at or below 65° or at 90°C and above. Growth may occur at a pH between 2 and 5, but optimal growth requires that the pH be between 2.5 and 3. No growth is detected at a pH of 1 or below or at a pH of 6 or above. S. tokodaii strain 7 is obligately aerobic and facultatively chemoheterotrophic thermoacidophile that grows by aerobic respiration and not by simple fermentation (6).

Ecology (including pathogenesis)

S. tokodaii strain 7 is an obligate anerobe that grows optimally at pH of 2.5-3 and 80 degrees Celsius. They are naturally occurring in hot springs, and have no known pathogenic effects. They contribute to their environment by converting hydrogen sulfide to sulfate (6).

Interesting feature

A particular interesting detail about Sulfolobus tokodaii is that it’s ability to convert hydrogen sulfide to sulfate can be harnessed and used for the purpose of treating industrial waste water (5). In addition to this, Sulfolobus tokodaii, along with Aeropyrum pernix, another hyperthermophillic Archaea, has been identified as a potential candidate for the oxidation of arsenic. This is significant because arsenic that is naturally found in the sediment but is only released by humans digging shallow wells. This is not entirely understood yet, but it is presumed that microbial metabolism is responsible for the release of the arsenic, and if the release can be understood than perhaps a solution can be found that will allow entire populations that are being exposed to unhealthy levels of arsenic to lessen their arsenic exposure (7).


(1) Albers, Sonja-Verena, and Benjamin H. Meyer. "Access : The Archaeal Cell Envelope : Nature Reviews Microbiology." Nature Publishing Group : Science Journals, Jobs, and Information. June 2011. Web. <>.

(2) Calzada, Alicia Wagner. Photograph. Beppu, Japan. Genome News Network. Web. <>.

(3) Kawarabayasi, Yutaka. "Complete Genome Sequence of an Aerobic Thermoacidophilic Crenarchaeon, Sulfolobus Tokodaii Strain7." Oxford Journals | Life Sciences | DNA Research. Web. 23 Oct. 2011. <>.

(4) Kuenen, J. G., and L. A. Robertson. "The Use of Natural Bacterial Populations for the Treatment of Sulphur-containing Wastewater." Biodegradation 3.2-3 (1992): 239-54. Print.

(5) Reinert, Birgit. "Sulfolobus Tokodaii: A Genome from Japan." Genome News Network - Home. Web. <>.

(6) "Research - Sulfolobus Tokodaii of Toshio Iwasaki Group Homepage|Nippon Medical School|日本医科大学|岩崎 俊雄 グループ ホームページ." 学校法人日本医科大学 : 法人本部. Web. <>.

(7) Silver, Simon, and Le T. Phung. "Genes and Enzymes Involved in Bacterial Oxidation and Reduction of Inorganic Arsenic."Applied and Environmental Microbiology 71.2 (2005): 599-608. Web. <>.

(8) "Sulfolobus Tokodaii Str. 7." NCBI. Web. <>.