![Microorganisms from the hypersaline Lake Tyrrell](https://upload.wikimedia.org/wikipedia/commons/1/11/Microorganisms_from_the_hypersaline_Lake_Tyrrell.jpg)
''Dunaliella salina'' is a type of
halophile
The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...
green
unicellular
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...
micro-
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
especially found in
hypersaline
A hypersaline lake is a landlocked body of water that contains significant concentrations of sodium chloride, brines, and other salts, with saline levels surpassing that of ocean water (3.5%, i.e. ).
Specific microbial species can thrive in h ...
environments, such as
salt lake
A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
s and
salt evaporation ponds
A salt evaporation pond is a shallow artificial salt pan designed to extract salts from sea water or other brines. The Salt pans are shallow and large of size because it will be easier for sunlight to travel and reach the sea water. Natural s ...
. Known for its
antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
activity because of its ability to create large amount of
carotenoids
Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, ...
, it is responsible for most of the
primary production
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
in
hypersaline
A hypersaline lake is a landlocked body of water that contains significant concentrations of sodium chloride, brines, and other salts, with saline levels surpassing that of ocean water (3.5%, i.e. ).
Specific microbial species can thrive in h ...
environments worldwide, and is also used in
cosmetics
Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...
and
dietary supplements
A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill (pharmacy), pill, capsule (pharmacy), capsule, tablet (pharmacy), tablet, powder, or liquid. A supplement can provide nutrients either extr ...
.
History
''Dunaliella salina'' was named by
Emanoil C. Teodoresco of
Bucharest, Romania
Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north of ...
after its original discoverer,
Michel Felix Dunal
Michel may refer to:
* Michel (name), a given name or surname of French origin (and list of people with the name)
* Míchel (nickname), a nickname (a list of people with the nickname, mainly Spanish footballers)
* Míchel (footballer, born 1963), ...
, who first scientifically reported sighting the organism in
saltern
A saltern is an area or installation for making salt. Salterns include modern salt-making works (saltworks), as well as hypersaline waters that usually contain high concentrations of halophilic microorganisms, primarily haloarchaea but also oth ...
evaporation ponds in
Montpellier, France in 1838. He initially named the organism ''Haematococcus salinus'' and ''Protococcus''. The organism was fully described as a new, separate genus simultaneously by Teodoresco and Clara Hamburger of
Heidelberg, Germany
Heidelberg (; Palatine German language, Palatine German: ''Heidlberg'') is a city in the States of Germany, German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914 ...
in 1905. Teodoresco was the first to publish his work, so he is generally given credit for this categorization.
Habitat
Few organisms can survive like ''D. salina'' does in such highly saline conditions as
salt evaporation ponds
A salt evaporation pond is a shallow artificial salt pan designed to extract salts from sea water or other brines. The Salt pans are shallow and large of size because it will be easier for sunlight to travel and reach the sea water. Natural s ...
. To survive, these organisms have high concentrations of
β-carotene
β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...
to protect against the intense light, and high concentrations of
glycerol
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
to provide protection against
osmotic pressure
Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane.
It is also defined as the measure of the tendency of a solution to take in a pure ...
. This offers an opportunity for commercial biological production of these substances.
[
It has been thought for a long time that the colour of ]pink lake
A pink lake is a lake that has a red or pink colour. This is often caused by the presence of salt-tolerant algae that produces carotenoids, such as ''Dunaliella salina'', usually in conjunction with specific bacteria, which may vary from lake ...
s was the result of this alga, as it has been found in many pink lakes and contains substances in a range of hues which include pink.[ However, research done in Australia since 2015 in ]Lake Hillier
Lake Hillier is a salt lake, saline lake on the edge of Middle Island (Western Australia), Middle Island, the largest of the islands and islets that make up the Recherche Archipelago in the Goldfields-Esperance region, off the south coast of We ...
found several species of halophilic bacteria
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 among ...
and archaea
Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebac ...
as well as several species of Dunaliella
''Dunaliella'' is a single-celled, photosynthetic green alga, that is characteristic for its ability to outcompete other organisms and thrive in hypersaline environments. It is mostly a marine organism, though there are a few freshwater species ...
, nearly all of which contain some pink, red or salmon-coloured pigment.
Morphology and characteristics
Species in the genus ''Dunaliella
''Dunaliella'' is a single-celled, photosynthetic green alga, that is characteristic for its ability to outcompete other organisms and thrive in hypersaline environments. It is mostly a marine organism, though there are a few freshwater species ...
'' are morphogically similar to ''Chlamydomonas reinhardtii
''Chlamydomonas reinhardtii'' is a single-cell green alga about 10 micrometres in diameter that swims with two flagella. It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an ...
'' with the main exception being that ''Dunaliella'' lack both a cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
and a contractile vacuole
A contractile vacuole (CV) is a sub-cellular structure (organelle) involved in osmoregulation. It is found predominantly in protists and in unicellular algae. It was previously known as pulsatile or pulsating vacuole.
Overview
The contractile v ...
. ''Dunaliella'' has two flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have f ...
of equal length and has a single cup-like chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
that often contains a central pyrenoid
Pyrenoids are sub-cellular micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. Annu. Rev. Plant Bio ...
. The chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
can hold large amounts of β-carotene
β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...
, which makes it appear orange-red. The β-carotene appears to protect the organism from long-term UV radiation
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
that ''D. salina'' is exposed to in its typical environments. ''D. salina'' comes in various shapes and symmetries depending on the conditions in its current environment.
''D. salina'' lacks a rigid cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
, which makes the organism susceptible to osmotic pressure
Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane.
It is also defined as the measure of the tendency of a solution to take in a pure ...
. Glycerol
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
is used as a means by which to maintain both osmotic balance and enzymatic activity. ''D. salina'' preserves a high concentration of glycerol by maintaining a cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
with low permeability to glycerol
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
and synthesizing large quantities of glycerol from starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
as a response to high extracellular salt concentration, which is why it tends to thrive in highly salinic environments.[
]
Reproduction and lifecycle
''D. salina'' can reproduce
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual org ...
asexually through division of motile vegetative cells and sexually through the fusion of two equal gametes
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
into a singular zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism.
In multicellula ...
. Though ''D. salina'' can survive in salinic environments, Martinez ''et al.'' determined that sexual activity of ''D. salina'' significantly decreases in higher salt concentrations (>10%) and is induced in lower salt concentrations. Sexual reproduction
Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...
begins when two ''D. salina''’s flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have f ...
touch leading to gamete fusion. The ''D. salina'' zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism.
In multicellula ...
is extraordinarily hardy and can survive exposure to fresh water and to dryness. After germination
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...
, the zygotes release up to 32 haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
daughter cells.
Commercial uses
''D. salina'' is responsible for most of the primary production
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
in hypersaline
A hypersaline lake is a landlocked body of water that contains significant concentrations of sodium chloride, brines, and other salts, with saline levels surpassing that of ocean water (3.5%, i.e. ).
Specific microbial species can thrive in h ...
environments worldwide.[
]
β-carotene
From a first pilot plant for ''D. salina'' cultivation for β-carotene
β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...
production established in the USSR
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
in 1966, the commercial cultivation of ''D. salina'' for the production of β-carotene throughout the world is now one of the success stories of halophile
The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...
biotechnology
Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used b ...
. Different technologies are used, from low-tech extensive cultivation in lagoons to intensive cultivation at high cell densities under carefully controlled conditions.
Anti-oxidant & nutritional supplement
Due to the abundance of β-carotene
β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...
, which is an anti-oxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricants, ...
as well as a vitamin A
Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...
precursor, ''D. salina'' is a popular pro-vitamin A food supplement
A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
and cosmetic additive. ''D. salina'' may also be a source of vitamin B12
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It ...
.[Kumudha A, Sarada R. Characterization of vitamin B12 in ''Dunaliella salina''. J Food Sci Technol. 2016;53:888-894.]
Glycerol
Attempts have been made to exploit the high concentrations of glycerol accumulated by ''D. salina'' as the basis for the commercial production of this compound. Although technically the production of glycerol from ''D. salina'' was shown to be possible, economic feasibility is low and no biotechnological operation exists to exploit the alga for glycerol production.[Chen BJ, Chi CH. Process development and evaluation for algal glycerol production. Biotechnol Bioengin. 1981;23:1267–1287. doi: 10.1002/bit.260230608.]
See also
* Lake Hillier
Lake Hillier is a salt lake, saline lake on the edge of Middle Island (Western Australia), Middle Island, the largest of the islands and islets that make up the Recherche Archipelago in the Goldfields-Esperance region, off the south coast of We ...
, Western Australia, Australia
* Lake Retba
Lac Rose (meaning Pink Lake) lies north of the Cap Vert peninsula of Senegal, some 30 km (18 miles) north-east of the capital, Dakar, in northwest Africa. It is named for its pink waters caused by '' Dunaliella salina'' algae and is known ...
, Senegal
* Seaweed
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...
References
Further reading
* Borowitzka, M.J. & Siva, C.J. (2007). The taxonomy of the genus Dunaliella (Chlorophyta, Dunaliellales) with emphasis on the marine and halophilic species. Journal of Applied Phycology 19: 567-590.
* Chen H., Lu Y. and Jiang J. “Comparative Analysis on the Key Enzymes of the Glycerol Cycle Metabolic Pathway in Dunaliella salina under Osmotic Stresses.” PLoS ONE, 2012, DOI: 10.1371/journal.pone.0037578
* Massjuk, N.P. & Lilitska, G.G. (2011). Dunaliellales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 152–157. Ruggell: A.R.A. Gantner Verlag K.-G..
* Mixed Carotenoids. Rejuvenal healthy aging, n.d. Web. 22 Nov 2012.
* Smith D., Lee R., Cushman J., Magnuson J., Tran D. and Polle J.” The Dunaliella salina organelle genomes: large sequences, inflated with intronic and intergenic DNA.” BMA Plant Biology, 2010. DOI: 10.1186/1471-2229-10-83
* Zhao, R., Cao, Y., Xu, H., Lv, L., Qiao, D. & Cao, Y. (2011). Analysis of expressed sequence tags from the green alga Dunaliella salina (Chlorophyta). Journal of Phycology 47(6): 1454-1460.
External links
*
MicrobeWiki reference on Dunaliella salina
{{Taxonbar, from=Q2441328
Chlamydomonadales