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Thermus thermophilus
Scientific classification
Domain:	Bacteria
Phylum:	Deinococcota
Class:	Deinococci
Order:	Thermales
Family:	Thermaceae
Genus:	Thermus
Species:	T. thermophilus
Binomial name
Thermus thermophilus (ex Oshima and Imahori 1974) Manaia et al. 1995

Thermus thermophilus is a Gram-negative bacterium used in a range of biotechnological applications, including as a model organism for genetic manipulation, structural genomics, and systems biology. The bacterium is extremely thermophilic, with an optimal growth temperature of about 65 °C (149 °F). Thermus thermophilus was originally isolated from a thermal vent within a hot spring in Izu, Japan by Tairo Oshima and Kazutomo Imahori. The organism has also been found to be important in the degradation of organic materials in the thermogenic phase of composting. T. thermophilus is classified into several strains, of which HB8 and HB27 are the most commonly used in laboratory environments. Genome analyses of these strains were independently completed in 2004. Thermus also displays the highest frequencies of natural transformation known to date.

Cell structure

Thermus thermophilus is a Gram-negative bacterium with an outer membrane that is composed of phospholipids and lipopolysaccharides. This bacterium also has a thin peptidoglycan (also known as murein) layer, in this layer there are 29 muropeptides which account for more than 85% of the total murein layer. The presence of Ala, Glu, Gly, Orn, N-acetyl glucosamine and N-acetylmuramic were found in the murein layer of this bacterium. Another unique feature of this murein layer is that the N-terminal Gly is substituted with phenylacetic acid. This is the first instance of phenylacetic acid found in the murein of bacterial cells. The composition and peptide cross-bridges found in this murein layer are typical of Gram-positive bacterium, but the amount, the degree of the cross-linkage and length of the glycan chain gives this bacterium its Gram-negative properties.

Survival mechanisms

Thermus thermophilus was originally found within a thermal vent in Japan. These bacteria can be found in a variety of geothermal environments. These Thermophiles require a more stringent DNA repair system, as DNA becomes unstable at high temperatures. The GC-content of this bacterium is about 69%, this contributes to the thermostability of this bacterium's genome.

Strains

The two most widely used strains in laboratory settings are HB27 and HB8. The strain HB27 is capable of living in an aerobic or anaerobic environment. It has a genome that consists of a main chromosome (1.89Mb long), as well as a megaplasmid, known as pTT27 (0.23Mb long). The chromosome of HB27 contains 1,968 protein coding genes, with 20% of these genes having no known function. While the megaplasmid contains 230 protein coding genes, about 39% of these genes have no known function.

The strain HB8 is also an aerobic organism and is a model organism for systems biology. It has a genome consisting of a plasmid, known as pTT8 (9.3kb long), that is coupled with a chromosome (1.85Mb), as well as a megaplasmid, also known as pTT27 (0.26Mb). This strain was found to be a polyploid organism, with a chromosome and megaplasmid copy number of about four to five.

Applications

This organism has been advantageous for industrial biotechnological fields as it is an excellent source of enzymes, more specifically thermozymes. One of these enzymes being the Tth DNA polymerase (rTth to emphasize it being recombinant).

rTth DNA polymerase is a recombinant thermostable DNA polymerase derived from Thermus thermophilus HB8, with optimal activity at 70-80 °C, used in some PCR applications. The enzyme possesses efficient reverse transcriptase activity in the presence of manganese. This enzyme is beneficial for amplification of GC-rich targets and for crude samples. It can be used in applications of PCR, RT-PCR and also primer extension. This polymerase has been shown to be resistant to DNA polymerase inhibitors present in clinical samples, it also has the capacity to detect RNA in the presence of inhibitors. Under the presence of inhibitors, it was shown to detect this RNA at a comparable level with its capacity to detect DNA.

See also

• Rapunzel bacteriophage

References

1. Oshima T, Imahori K (January 1974). "Description of Thermus thermophilus (Yoshida and Oshima) comb. nov., a nonsporulating thermophilic bacterium from a Japanese thermal spa". International Journal of Systematic and Evolutionary Microbiology. 24 (1): 102–12. doi:10.1099/00207713-24-1-102.
2. Beffa T, Blanc M, Lyon PF, Vogt G, Marchiani M, Fischer JL, Aragno M (May 1996). "Isolation of Thermus strains from hot composts (60 to 80 °C)". Applied and Environmental Microbiology. 62 (5): 1723–7. Bibcode:1996ApEnM..62.1723B. doi:10.1128/AEM.62.5.1723-1727.1996. PMC 167946. PMID 8633870.
3. Henne A, Brüggemann H, Raasch C, Wiezer A, Hartsch T, Liesegang H, et al. (May 2004). "The genome sequence of the extreme thermophile Thermus thermophilus". Nature Biotechnology. 22 (5): 547–53. doi:10.1038/nbt956. PMID 15064768. S2CID 25469576.
4. Koyama, Y; Hoshino, T; Tomizuka, N; Furukawa, K (1986). "Genetic transformation of the extreme thermophile Thermus thermophilus and of other Thermus spp". Journal of Bacteriology. 166 (1): 338–340. doi:10.1128/jb.166.1.338-340.1986. PMC 214599. PMID 3957870.
5. Quintela, J C; Pittenauer, E; Allmaier, G; Arán, V; de Pedro, M A (September 1995). "Structure of peptidoglycan from Thermus thermophilus HB8". Journal of Bacteriology. 177 (17): 4947–4962. doi:10.1128/jb.177.17.4947-4962.1995. ISSN 0021-9193. PMC 177270. PMID 7665471.
6. Wang, Quanhui; Cen, Zhen; Zhao, Jingjing (2015-03-01). "The Survival Mechanisms of Thermophiles at High Temperatures: An Angle of Omics". Physiology. 30 (2): 97–106. doi:10.1152/physiol.00066.2013. ISSN 1548-9213. PMID 25729055.
7. ^ Ohtani, Naoto; Tomita, Masaru; Itaya, Mitsuhiro (2010-10-15). "An Extreme Thermophile, Thermus thermophilus, Is a Polyploid Bacterium". Journal of Bacteriology. 192 (20): 5499–5505. doi:10.1128/JB.00662-10. ISSN 0021-9193. PMC 2950507. PMID 20729360.
8. Carr, Jennifer F.; Danziger, Michael E.; Huang, Athena L.; Dahlberg, Albert E.; Gregory, Steven T. (2015-03-15). "Engineering the Genome of Thermus thermophilus Using a Counterselectable Marker". Journal of Bacteriology. 197 (6): 1135–1144. doi:10.1128/JB.02384-14. ISSN 0021-9193. PMC 4336342. PMID 25605305.
9. ^ Cai D, Behrmann O, Hufert F, Dame G, Urban G (2018-01-02). "Capacity of rTth polymerase to detect RNA in the presence of various inhibitors". PLOS ONE. 13 (1): e0190041. Bibcode:2018PLoSO..1390041C. doi:10.1371/journal.pone.0190041. PMC 5749758. PMID 29293599.
10. "rTth DNA Polymerase - TOYOBO USA". www.toyobousa.com. Retrieved 2021-05-07.

External links

• Thermus thermophilus HB27 genome page.
• Thermus thermophilus HB8 genome page.
• Structural-biological whole cell project of Thermus thermophilus HB8.
• Isolation of Thermus strains from hot composts (60°C-80°C)
• Whole Cell Project of Thermus thermophilus HB8: Database
• Type strain of Thermus thermophilus at BacDive - the Bacterial Diversity Metadatabase

• Model organisms
• Thermophiles
• Thermozoa
• Deinococcota