| Thermotoga neapolitana | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Phylum: | Thermotogota |
| Class: | Thermotogae |
| Order: | Thermotogales |
| Family: | Thermotogaceae |
| Genus: | Thermotoga |
| Species: | T. neapolitana |
| Binomial name | |
| Thermotoga neapolitana Huber et al., 1986 | |
Thermotoga neapolitana is a hyperthermophilic organism that is a member of the order Thermotogales. [1]
Thermotoga neapolitana was discovered in 1985 in Lucrino, Italy in a hotspring environment by Shimshon Belkin, Carl. O Wirsen, and Holger W. Jannasch of the University of California, Berkeley. [2]
Thermotoga neapolitana is considered thermophilic with a livable temperature range of 50–95 °C. The optimum temperature was found to be 77 °C, making it nearly hyperthermophilic. [2] There is also evidence that it could be found in saline environments, due to its ability to thrive in moderately halophilic environments. [3]
Thermotoga neapolitana is a rod-shaped, Gram-negative bacterium. [4] It is distinguishable by a thick periplasmic cell wall. [2] Generally, they are found to be 0.2–5 μm, but they may reach sizes of up to 100 μm. It is non-sporulating - this along with its rod-shape and Gram-negative features are characteristic of the Order Thermotogales. [2]
Using a guar-gum based medium, β-mannanase, β-mannosidase, α-galactosidase have been purified. These galactomannans are associated with allowing an organism to endure harsh environments (through stabilization of the membrane), such as high temperatures. These enzymes help provide simple saccharides to the organism. Polymers similar to those degraded by T. neopolitana are often used as storage polymers by plants. This may show that as the geothermal environments in which this organism is found have changed and biodiversified, so might the metabolism of this hyperthermophile. [5]
Thermotoga neapolitana is strictly heterotrophic for its metabolic needs. [2] It can also facultatively reduce elemental sulfur to hydrogen sulfide. [2] In growth experiments, it was found to multiply rapidly with glucose and yeast abstract. After 24 hours of growth, the longest rods divide into two rods, most likely in response to decreases levels of glucose availability. [2] Glucose, sucrose, lactose, and starch nutrients all support growth when used as a sole source of energy. Low level of growth occurred with exposure to only peptone or tryptone. Thermotoga neapolitana is unable to metabolize acetate, lactate, formate, pyruvate, propionate, mannitol, ethanol, methanol, glycerol, glutamate, or glycine. [2] Chloramphenicol, vancomycin, streptomycin were all found to completely inhibit growth, though it was resistant to rifampin. [2] Growth can be found within a 0.25-6% NaCl range exclusively, with no survival outside of this limit. [3] It was originally thought to be strictly anaerobic, but can also survive under micro-aerophilic environments. [6]
Thermotoga neapolitana can facultatively reduce elemental sulfur to hydrogen sulfide. This allows for heightened reproductive rates of the organism - up to four-fold with elemental sulfur availability. This process requires the availability of a utilizable carbon source. Sulfuric acid and thiosulfate cannot be used for reduction. The presence of sulfide acts to inhibit growth of the organism. In a concentration of 10 mM, sulfide will inhibit growth by up to 95%. [2]
Thermotoga neapolitana shows promise as a useful bacterium due to its hydrogen production. It is capable of producing upwards of 25–30% hydrogen in the space it occupies when tested. The other notable gas it produces is carbon dioxide at a level of 12–15% of the total headspace. [4] Despite different levels of hydrogen production under varying conditions, the hydrogen gas to carbon dioxide ratio is approximately 2:1. [6] The hydrogen produced is considered extremely clean with a carbon monoxide level in the headspace of less than 50 parts per million. [6] This may be promising from a bioengineering standpoint as hydrogen gas is commonly sought after as a possible alternative to fossil fuel burning for energy consumption. [6] Though originally thought to be strictly anaerobic, Thermotoga neapolitana is more efficient in its catabolic pathways, especially its hydrogen production, when there are low levels of oxygen available (slightly above 10% total composition) in comparison to anoxic environments. [4]
Thermotoga neapolitana shows a DNA base composition of 41.3% Guanine + Cytosine(and therefore 58.7% Adenine + Thymine). [2] Using DNA-DNA hybridization, T. neapolitana was found to have a 74% homology with Thermotoga thermarum. [3] T. neapolitana is also closely related to Thermotoga maritima , which was also discovered in geothermal environment. [3] The ino1 gene is present in T. neapolitana. Most eukaryotes possess this gene, and it sometimes expressed to produce the rare osmolyte di-miyo-inositol 1,1' phosphate (DIP). This is linked to hyperthermilic tendencies because it protects the organism from high temperatures and salinities. The osmolyte may link T. neapolitana as well as other members of Thermotoga to Archaeans and Aquificales, the only other groups in which it is found. [7]
Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the sources of carbon can be of organic or inorganic origin.
In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules and nutrients into organic matter using the oxidation of inorganic compounds or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically important taxa include the sulfur-oxidizing Gammaproteobacteria, the Campylobacterota, the Aquificota, the methanogenic archaea, and the neutrophilic iron-oxidizing bacteria.
Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate (SO2−
4) as terminal electron acceptor, reducing it to hydrogen sulfide (H2S). Therefore, these sulfidogenic microorganisms "breathe" sulfate rather than molecular oxygen (O2), which is the terminal electron acceptor reduced to water (H2O) in aerobic respiration.
The Thermotogota are a phylum of the domain Bacteria. The phylum contains a single class, Thermotogae. The phylum Thermotogota is composed of Gram-negative staining, anaerobic, and mostly thermophilic and hyperthermophilic bacteria.
"Aquifex aeolicus" is a chemolithoautotrophic, Gram-negative, motile, hyperthermophilic bacterium. "A. aeolicus" is generally rod-shaped with an approximate length of 2.0-6.0μm and a diameter of 0.4-0.5μm. "A. aeolicus" is neither validly nor effectively published and, having no standing in nomenclature, should be styled in quotation marks. It is one of a handful of species in the Aquificota phylum, an unusual group of thermophilic bacteria that are thought to be some of the oldest species of bacteria, related to filamentous bacteria first observed at the turn of the century. "A. aeolicus" is also believed to be one of the earliest diverging species of thermophilic bacteria. "A. aeolicus" grows best in water between 85 °C and 95 °C, and can be found near underwater volcanoes or hot springs. It requires oxygen to survive but has been found to grow optimally under microaerophilic conditions. Due to its high stability against high temperature and lack of oxygen, "A. aeolicus" is a good candidate for biotechnological applications as it is believed to have potential to be used as hydrogenases in an attractive H2/O2 biofuel cell, replacing chemical catalysts. This can be useful for improving industrial processes.
Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product of these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H
2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
Thermococcus celer is a Gram-negative, spherical-shaped archaeon of the genus Thermococcus. The discovery of T. celer played an important role in rerooting the tree of life when T. celer was found to be more closely related to methanogenic Archaea than to other phenotypically similar thermophilic species. T. celer was the first archaeon discovered to house a circularized genome. Several type strains of T. celer have been identified: Vu13, ATCC 35543, and DSM 2476.
Thermococcus kodakarensis is a species of thermophilic archaea. The type strain T. kodakarensis KOD1 is one of the best-studied members of the genus.
Nautilia profundicola is a Gram-negative chemolithoautotrophic bacterium found around hydrothermal vents in the deep ocean. It was first discovered in 1999 on the East Pacific Rise at depth of 2,500 metres (8,200 ft), on the surface of the polychaete worm Alvinella pompejana. Nautilia profundicola lives symbiotically on the dorsal hairs of A. pompejana but they may also form biofilms and live independently on the walls of hydrothermal vents. The ability of N. profundicola to survive in an anaerobic environment rich in sulfur, H2 and CO2 of varying temperature makes it a useful organism to study, as these are the conditions that are theorized to have prevailed around the time of the earliest life on earth.
Thermotoga maritima is a hyperthermophilic, anaerobic organism that is a member of the order Thermotogales. T. maritima is well known for its ability to produce hydrogen (clean energy) and it is the only fermentative bacterium that has been shown to produce Hydrogen more than the Thauer limit (>4 mol H2 /mol glucose). It employs [FeFe]-hydrogenases to produce hydrogen gas (H2) by fermenting many different types of carbohydrates.
Thermotoga hypogea is a hyperthermophilic organism that is a member of the order Thermotogales. It is thermophilic, xylanolytic, glucose-fermenting, strictly anaerobic and rod-shaped. The type strain of T. hypogea is SEBR 7054.
Thermotoga elfii is a rod-shaped, glucose-fermenting bacterium. The type strain of T. elfii is SEBR 6459T. The genus Thermotoga was originally thought to be strictly found surrounding submarine hydrothermal vents, but this organism was subsequently isolated in African oil wells in 1995. A protective outer sheath allows this microbe to be thermophilic. This organism cannot function in the presence of oxygen making it strictly anaerobic. Some research proposes that the thiosulfate-reducing qualities in this organism could lead to decreased bio-corrosion in oil equipment in industrial settings.
Thermotoga petrophila is a hyperthermophilic, anaerobic, non-spore-forming, rod-shaped, fermentative heterotroph, with type strain RKU-1T. T. petrophila was first discovered and isolated from an oil reservoir off of the coast of Japan and was deemed genetically distinct from its sister clades. Because these organism are found in deep, hot aquatic settings, they have become of great interest for biotechnology due to their enzymes functioning at high temperatures and pressures.
Thermotoga naphthophila is a hyperthermophilic, anaerobic, non-spore-forming, rod-shaped fermentative heterotroph, with type strain RKU-10T.
Persephonella marina is a Gram-negative, rod shaped bacteria that is a member of the Aquificota phylum. Stemming from Greek, the name Persephonella is based upon the mythological goddess Persephone. Marina stems from a Latin origin, meaning "belonging to the sea". It is a thermophile with an obligate chemolithoautotrophic metabolism. Growth of P. marina can occur in pairs or individually, but is rarely seen aggregating in large groups. The organism resides on sulfidic chimneys in the deep ocean and has never been documented as a pathogen.
Thermococcus peptonophilus is a fast-growing hyperthermophilic archaeon. It is coccus-shaped, obligately anaerobic and about 0.7–2 μm in diameter. It is a strict anaerobe and grows exclusively on complex substrates, such as peptone, casein, tryptone, and yeast extract. It cannot use carbon dioxide as a source of carbon. Although it can grow somewhat in the absence of elemental sulfur, it prefers sulfur.
Microbial oxidation of sulfur is the oxidation of sulfur by microorganisms to build their structural components. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy to survive, grow and reproduce. Some inorganic forms of reduced sulfur, mainly sulfide (H2S/HS−) and elemental sulfur (S0), can be oxidized by chemolithotrophic sulfur-oxidizing prokaryotes, usually coupled to the reduction of oxygen (O2) or nitrate (NO3−). Anaerobic sulfur oxidizers include photolithoautotrophs that obtain their energy from sunlight, hydrogen from sulfide, and carbon from carbon dioxide (CO2).
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy from the geological activity at Hydrothermal vents to fix carbon into organic forms. Viruses are also a part of the hydrothermal vent microbial community and their influence on the microbial ecology in these ecosystems is a burgeoning field of research.
The evolution of bacteria has progressed over billions of years since the Precambrian time with their first major divergence from the archaeal/eukaryotic lineage roughly 3.2-3.5 billion years ago. This was discovered through gene sequencing of bacterial nucleoids to reconstruct their phylogeny. Furthermore, evidence of permineralized microfossils of early prokaryotes was also discovered in the Australian Apex Chert rocks, dating back roughly 3.5 billion years ago during the time period known as the Precambrian time. This suggests that an organism in of the phylum Thermotogota was the most recent common ancestor of modern bacteria.
Shimshon Belkin is an environmental microbiologist, a Professor Emeritus at the Department of Plant and Environmental Sciences at the Alexander Silberman Institute of Life Sciences of the Hebrew University of Jerusalem, Israel.
