Thermotoga maritima
Thermotoga maritima | |
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Outline of a Thermotoga maritima section showing the "toga" | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Thermotogota |
Class: | Thermotogae |
Order: | Thermotogales
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Family: | Thermotogaceae |
Genus: | Thermotoga |
Species: | T. maritima
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Binomial name | |
Thermotoga maritima Huber et al., 1986
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Thermotoga maritima is a hyperthermophilic, anaerobic organism that is a member of the order
History
First discovered in the sediment of a marine geothermal area near Vulcano, Italy, Thermotoga maritima resides in hot springs as well as hydrothermal vents.[3] The ideal environment for the organism is a water temperature of 80 °C (176 °F), though it is capable of growing in waters of 55–90 °C (131–194 °F).[4] Thermotoga maritima is the only bacterium known to grow at this high a temperature; the only other organisms known to live in environments this extreme are members of the domain Archaea. The hyperthermophilic abilities of T. maritima, along with its deep lineage, suggests that it is potentially a very ancient organism.[5]
Physical attributes
Thermotoga maritima is a non-
Metabolism
As an anaerobic fermentative
Clean energy (biohydrogen) from T. maritima
Energy is a growing need of the world and it is expected to grow in the next 20 years. Among various energy sources, hydrogen serves as the best energy carrier due to its higher energy content per unit weight. T. maritima is one of fermentative bacteria that produces hydrogen to levels that approach the thermodynamic limit (4 mol H2/ mol glucose). However, similar to other fermentative bacteria, the hydrogen yield in this bacterium does not go beyond 4 mol H2 / glucose (Thaeur limit) because of its inherent nature to use more energy for its own cell division to grow rapidly than producing H2. Because of these reasons fermentative bacteria have not been thought to produce higher amounts of hydrogen at a commercial scale. Overcoming this limit by improving the conversion of sugar to H2 could lead to a superior H2 producing biological system that may supersede fossil fuel-based H2 production.
Metabolic engineering in this bacterium led to development of strains of T. maritima that surpassed the Thauer limit of hydrogen production.[1] One of the strains, also known as Tma200, produced 5.77 mol H2/ mol glucose which is the highest yield so far reported in a fermentative bacterium. In this strain, energy redistribution, and metabolic rerouting through the pentose phosphate pathway (PPP) generated excess reductants while uncoupling growth from hydrogen synthesis. Uncoupling of growth from product formation has been viewed as a viable strategy to maximize the product yield which has been achieved in the higher hydrogen producing bacterium. Similar strategies can be adopted for other hydrogen producing bacterium to maximize product yields.
Hydrogenase activity
Genomic composition
The genome of T. maritima consists of a single circular 1.8 megabase chromosome encoding for 1877 proteins.[9] Within its genome it has several heat and cold shock proteins that are most likely involved in metabolic regulation and response to environmental temperature changes.[7] It shares 24% of its genome with members of the Archaea; the highest percentage overlap of any bacteria.[10] This similarity suggests horizontal gene transfer between Archaea and ancestors of T. maritima and could help to explain why T. maritima is capable of surviving in such extreme temperatures and conditions. The genome of T. maritima has been sequenced multiple times. Genome resequencing of T. maritima MSB8 genomovar DSM3109 [11][9] determined that the earlier sequenced genome was an evolved laboratory variant of T. maritima with an approximately 8-kb deletion. Moreover, a variety of duplicated genes and direct repeats in its genome suggest their role in intra-molecular homologous recombination leading to genes deletion. A strain with a 10-kb gene deletion has been developed using the experimental microbial evolution in T. maritima.[12]
Genetic system of Thermotoga maritima
Thermotoga maritima has a great potential in hydrogen synthesis because it can ferment a wide variety of sugars and has been reported to produce the highest amount of H2 (4 mol H2/ mol
For the first time, the use of this marker allowed the development of an
Evolution
Thermotoga maritima contains homologues of several
References
- ^ PMID 29959252.
- PMID 7775441.
- ^ "Hyperthermophilic organism that shows extensive horizontal gene transfer from archaea". BioProject. National Center for Biotechnology Information. 2003. Retrieved January 14, 2012.
- ^ S2CID 12709437.
- PMID 8305426.
- ^ a b c "Geothermal organisms". Montana State University. Retrieved January 14, 2012.
- ^ S2CID 4420157.
- PMID 29251926.
- ^ PMID 23637642.
- PMID 11230537.
- PMID 21764944.
- ^ PMID 26021931.
- PMID 16237010.
- ^ PMID 27940539.
- PMID 28687653.