''Thermus thermophilus'' is a

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

used in a range of biotechnological applications, including as a model organism for

genetic manipulation Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including ...

structural genomics Structural genomics seeks to describe the 3-dimensional structure of every protein encoded by a given genome. This genome-based approach allows for a high-throughput method of structure determination by a combination of experimental and modeling ...

, and systems biology. The bacterium is extremely

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

, with an optimal growth temperature of about . ''Thermus thermophilus'' was originally isolated from a thermal vent within a

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by c ...

Izu Izu may refer to: Places *Izu Province, a part of modern-day Shizuoka prefecture in Japan **Izu, Shizuoka, a city in Shizuoka prefecture **Izu Peninsula, near Tokyo **Izu Islands, located off the Izu Peninsula People with the surname

*, Japane ...

, 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 Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...

. ''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.

Cell Structure

''Thermus thermophilus'' is a Gram-negative bacterium with an outer membrane that is composed of phospholipids and

lipopolysaccharide Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer ...

s. This bacterium also has a thin

peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ba ...

(also known as

murein Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ba ...

) 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 In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

, 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 A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...

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 In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature. ...

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 Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cel ...

anaerobic environment Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 p ...

. It has a genome that consists of a main

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

(1.89Mb long), as well as a

megaplasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; howe ...

, 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 Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics Aerobics is a form of physical exercise that combines rhythmic aerobic exe ...

and is a model organism for systems biology. It has a

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...

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 Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

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 A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create ...

derived from ''Thermus thermophilus'' HB8, with optimal activity at 70-80 °C, used in some PCR applications. The

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

possesses efficient reverse transcriptase activity in the presence of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

. 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.

References

External links

''Thermus thermophilus'' HB27 genome page.

''Thermus thermophilus'' HB8 genome page.

* ttp://aem.asm.org/cgi/content/abstract/62/5/1723 Isolation of ''Thermus'' strains from hot composts (60ºC-80ºC)
Whole Cell Project of ''Thermus thermophilus'' HB8: DatabaseType strain of ''Thermus thermophilus'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q139470 Model organisms Thermophiles Thermozoa