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32-443: 93; see text Suaeda is a genus of plants also known as seepweeds and sea-blites . Most species are confined to saline or alkaline soil habitats, such as coastal salt-flats and tidal wetlands. Many species have thick, succulent leaves, a characteristic seen in various plant genera that thrive in salty habitats ( halophile plants). There are about 110 species in the genus Suaeda . The most common species in northwestern Europe

64-602: A breed of sheep originating from Orkney, Scotland . They have limited access to freshwater sources on the island and their only food source is seaweed . They have adapted to handle salt concentrations that would kill other breeds of sheep. Halotolerance Halotolerance is the adaptation of living organisms to conditions of high salinity . Halotolerant species tend to live in areas such as hypersaline lakes , coastal dunes , saline deserts , salt marshes , and inland salt seas and springs . Halophiles are organisms that live in highly saline environments, and require

96-401: A group of archaea, which require at least a 2 M salt concentration and are usually found in saturated solutions (about 36% w/v salts). These are the primary inhabitants of salt lakes, inland seas, and evaporating ponds of seawater, such as the deep salterns , where they tint the water column and sediments bright colors. These species most likely perish if they are exposed to anything other than

128-722: A red color from carotenoid compounds, notably bacteriorhodopsin . Halophiles can be found in water bodies with salt concentration more than five times greater than that of the ocean, such as the Great Salt Lake in Utah, Owens Lake in California, the Lake Urmia in Iran, the Dead Sea , and in evaporation ponds . They are theorized to be a possible analogues for modeling extremophiles that might live in

160-541: A traditional festive dish called either revoltijo or romeritos . It is also eaten as wild greens ( quelites ) , or as edible herbs grown as part of the crop-growing system called milpa . 93 species are accepted. Halophile While most halophiles are classified into the domain Archaea , there are also bacterial halophiles and some eukaryotic species, such as the alga Dunaliella salina and fungus Wallemia ichthyophaga . Some well-known species give off

192-648: A very high-concentration, salt-conditioned environment. These prokaryotes require salt for growth. The high concentration of sodium chloride in their environment limits the availability of oxygen for respiration. Their cellular machinery is adapted to high salt concentrations by having charged amino acids on their surfaces, allowing the retention of water molecules around these components. They are heterotrophs that normally respire by aerobic means. Most halophiles are unable to survive outside their high-salt native environments. Many halophiles are so fragile that when they are placed in distilled water, they immediately lyse from

224-565: Is S. maritima . It grows along the coasts, especially in saltmarsh areas, and is known in Britain as "common sea-blite", but as "herbaceous seepweed" in the USA. It is also common along the east coast of North America from Virginia northward. One of its varieties is common in tropical Asia on the land-side edge of mangrove tidal swamps. Another variety of this polymorphic species is common in tidal zones all around Australia ( Suaeda maritima var. australis

256-401: Is a ubiquitous genus of small halophilic crustaceans living in salt lakes (such as Great Salt Lake) and solar salterns that can exist in water approaching the precipitation point of NaCl (340 g/L) and can withstand strong osmotic shocks due to its mitigating strategies for fluctuating salinity levels, such as its unique larval salt gland and osmoregulatory capacity. North Ronaldsay sheep are

288-558: Is also classed as S. australis ). On the coasts of the Mediterranean Sea a common Suaeda species is S. vera . This is known as "shrubby sea-blite" in English. It grows taller and forms a bush. The name Suaeda comes from an oral (non-literary) Arabic name for the Suaeda vera species transliterated as suaed , sawād or suēd , and it was assigned as the genus name by

320-542: Is in the Makgadikgadi Pans , a large hypersaline lake in Botswana . Fungi from habitats with high concentration of salt are mostly halotolerant (i.e. they do not require salt for growth) and not halophilic. Halophilic fungi are a rare exception. Halotolerant fungi constitute a relatively large and constant part of hypersaline environment communities, such as those in the solar salterns . Well studied examples include

352-407: Is reached through the use of stress proteins and compatible cytoplasm osmotic solutes. To exist in such conditions, halophytes tend to be subject to the uptake of high levels of salt into their cells, and this is often required to maintain an osmotic potential lower than that of the soil to ensure water uptake. High salt concentrations within the cell can be damaging to sensitive organelles such as

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384-435: Is the entire intracellular machinery (enzymes, structural proteins, etc.) must be adapted to high salt levels, whereas in the compatible solute adaptation, little or no adjustment is required to intracellular macromolecules; in fact, the compatible solutes often act as more general stress protectants, as well as just osmoprotectants. Of particular note are the extreme halophiles or haloarchaea (often known as halobacteria ),

416-557: The S10-spc cluster were observed to have an inverse relationship with the halophilicity/halotolerance levels in both bacteria and archaea. At the DNA level, the halophiles exhibit distinct dinucleotide and codon usage. Halobacteriaceae is a family that includes a large part of halophilic archaea. The genus Halobacterium under it has a high tolerance for elevated levels of salinity. Some species of halobacteria have acidic proteins that resist

448-1039: The salinity to survive, while halotolerant organisms (belonging to different domains of life) can grow under saline conditions, but do not require elevated concentrations of salt for growth. Halophytes are salt-tolerant higher plants. Halotolerant microorganisms are of considerable biotechnological interest. Fields of scientific research relevant to halotolerance include biochemistry , molecular biology , cell biology , physiology , ecology , and genetics . An understanding of halotolerance can be applicable to areas such as arid-zone agriculture , xeriscaping , aquaculture (of fish or algae), bioproduction of desirable compounds (such as phycobiliproteins or carotenoids ) using seawater to support growth, or remediation of salt-affected soils. In addition, many environmental stressors involve or induce osmotic changes, so knowledge gained about halotolerance can also be relevant to understanding tolerance to extremes in moisture or temperature. Goals of studying halotolerance include increasing

480-552: The 18th century taxonomist Peter Forsskål during his visit to the Red Sea area in the early 1760s. Forsskål's book, Flora Aegyptiaco-Arabica , published 1775, in Latin, declares Suæda as a newly created genus name, with the name taken from an Arabic name Suæd and presents the species members of the new genus. The genus includes plants using either C 3 or C 4 carbon fixation. The latter pathway evolved independently three times in

512-447: The addition of salt. The fermentation of salty foods (such as soy sauce , Chinese fermented beans , salted cod , salted anchovies , sauerkraut , etc.) often involves halophiles as either essential ingredients or accidental contaminants. One example is Chromohalobacter beijerinckii , found in salted beans preserved in brine and in salted herring . Tetragenococcus halophilus is found in salted anchovies and soy sauce. Artemia

544-623: The agricultural productivity of lands affected by soil salination or where only saline water is available. Conventional agricultural species could be made more halotolerant by gene transfer from naturally halotolerant species (by conventional breeding or genetic engineering ) or by applying treatments developed from an understanding of the mechanisms of halotolerance. In addition, naturally halotolerant plants or microorganisms could be developed into useful agricultural crops or fermentation organisms. Tolerance of high salt conditions can be obtained through several routes. High levels of salt entering

576-437: The buildup of cyclites and soluble sugars. The buildup of these compounds allow for the balancing of the osmotic effect while preventing the establishment of toxic concentrations of salt or requiring the maintenance of high concentration gradients. The extent of halotolerance varies widely amongst different species of bacteria. A number of cyanobacteria are halotolerant; an example location of occurrence for such cyanobacteria

608-509: The change in osmotic conditions. Halophiles use a variety of energy sources and can be aerobic or anaerobic; anaerobic halophiles include phototrophic, fermentative, sulfate-reducing, homoacetogenic, and methanogenic species. The Haloarchaea, and particularly the family Halobacteriaceae, are members of the domain Archaea , and comprise the majority of the prokaryotic population in hypersaline environments . Currently, 15 recognised genera are in

640-726: The chloroplast, so sequestration of salt is seen. Under this action, salt is stored within the vacuole to protect such delicate areas. If high salt concentrations are seen within the vacuole, a high concentration gradient will be established between the vacuole and the cytoplasm, leading to high levels of energy investment to maintain this state. Therefore, the accumulation of compatible cytoplasmic osmotic solutes can be seen to prevent this situation from occurring. Amino acids such as proline accumulate in halophytic Brassica species, quaternary ammonium bases such as Glycine Betaine and sugars have been shown to act in this role within halophytic members of Chenopodiaceae and members of Asteraceae show

672-402: The denaturing effects of salts. Halococcus is another genus of the family Halobacteriaceae. Some hypersaline lakes are habitat to numerous families of halophiles. For example, the Makgadikgadi Pans in Botswana form a vast, seasonal, high-salinity water body that manifests halophilic species within the diatom genus Nitzschia in the family Bacillariaceae , as well as species within

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704-419: The environment. The most common compatible solutes are neutral or zwitterionic , and include amino acids , sugars , polyols , betaines , and ectoines , as well as derivatives of some of these compounds. The second, more radical adaptation involves selectively absorbing potassium (K ) ions into the cytoplasm. This adaptation is restricted to the extremely halophilic archaeal family Halobacteriaceae ,

736-561: The family. The domain Bacteria (mainly Salinibacter ruber ) can comprise up to 25% of the prokaryotic community, but is more commonly a much lower percentage of the overall population. At times, the alga Dunaliella salina can also proliferate in this environment. A comparatively wide range of taxa has been isolated from saltern crystalliser ponds, including members of these genera: Haloferax, Halogeometricum, Halococcus, Haloterrigena, Halorubrum, Haloarcula , and Halobacterium . However,

768-582: The genus Lovenula in the family Diaptomidae . Owens Lake in California also contains a large population of the halophilic bacterium Halobacterium halobium . Wallemia ichthyophaga is a basidiomycetous fungus , which requires at least 1.5 M sodium chloride for in vitro growth, and it thrives even in media saturated with salt. Obligate requirement for salt is an exception in fungi. Even species that can tolerate salt concentrations close to saturation (for example Hortaea werneckii ) in almost all cases grow well in standard microbiological media without

800-480: The genus and is now used by around 40 species. S. aralocaspica , classified in its own section Borszczowia , uses a particular type of C 4 photosynthesis without the typical "Kranz" leaf anatomy. In the medieval and early post-medieval centuries suaeda was harvested and burned, and the ashes were processed as a source for sodium carbonate for use in glass-making; see glasswort . In Mexico, some species such as Suaeda pulvinata , called romeritos , are cooked in

832-510: The high salinities, halophiles employ two differing strategies to prevent desiccation through osmotic movement of water out of their cytoplasm. Both strategies work by increasing the internal osmolarity of the cell. The first strategy is employed by some archaea, the majority of halophilic bacteria, yeasts , algae , and fungi ; the organism accumulates organic compounds in the cytoplasm— osmoprotectants which are known as compatible solutes. These can be either synthesised or accumulated from

864-412: The moderately halophilic bacterial order Halanaerobiales , and the extremely halophilic bacterium Salinibacter ruber . The presence of this adaptation in three distinct evolutionary lineages suggests convergent evolution of this strategy, it being unlikely to be an ancient characteristic retained in only scattered groups or passed on through massive lateral gene transfer. The primary reason for this

896-419: The most readily isolated and studied genera may not in fact be significant in the in situ community. This is seen in cases such as the genus Haloarcula , which is estimated to make up less than 0.1% of the in situ community, but commonly appears in isolation studies. The comparative genomic and proteomic analysis showed distinct molecular signatures exist for the environmental adaptation of halophiles. At

928-479: The plant can trigger ionic imbalances which cause complications in respiration and photosynthesis, leading to reduced rates of growth, injury and death in severe cases. To be considered tolerant of saline conditions, the protoplast must show methods of balancing the toxic and osmotic effects of the increased salt concentrations. Halophytic vascular plants can survive on soils with salt concentrations around 6%, or up to 20% in extreme cases. Tolerance of such conditions

960-439: The protein level, the halophilic species are characterized by low hydrophobicity, an overrepresentation of acidic residues, underrepresentation of Cys, lower propensities for helix formation, and higher propensities for coil structure. The core of these proteins is less hydrophobic, such as DHFR , that was found to have narrower β-strands. In one study, the net charges (at pH 7.4) of the ribosomal proteins (r-proteins) that comprise

992-804: The salty subsurface water ocean of Jupiter's Europa and similar moons. Halophiles are categorized by the extent of their halotolerance : slight, moderate, or extreme. Slight halophiles prefer 0.3 to 0.8 M (1.7 to 4.8%—seawater is 0.6 M or 3.5%), moderate halophiles 0.8 to 3.4 M (4.7 to 20%), and extreme halophiles 3.4 to 5.1 M (20 to 30%) salt content. Halophiles require sodium chloride (salt) for growth, in contrast to halotolerant organisms, which do not require salt but can grow under saline conditions. High salinity represents an extreme environment in which relatively few organisms have been able to adapt and survive. Most halophilic and all halotolerant organisms expend energy to exclude salt from their cytoplasm to avoid protein aggregation (' salting out '). To survive

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1024-509: The viable counts in these cultivation studies have been small when compared to total counts, and the numerical significance of these isolates has been unclear. Only recently has it become possible to determine the identities and relative abundances of organisms in natural populations, typically using PCR -based strategies that target 16 S small subunit ribosomal ribonucleic acid (16S rRNA) genes. While comparatively few studies of this type have been performed, results from these suggest that some of

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