Antarctica has a harsh environment, is the coldest region in the world, and because it is a "white world", the ability to reflect light is strong, resulting in strong ultraviolet radiation in this area. Even so, there are still some creatures that can survive tenaciously in Antarctica, such as penguins, seals, krill and so on.
▲ Antarctica and some of the creatures that live in antarctica
In addition, microorganisms can be detected in all habitats in Antarctica, including lakes, ponds, rivers, streams, rocks, soils, etc. One of the reasons microbes can survive in such a harsh environment is the pigment they produce on their own. Some pigments produced by microorganisms have the function of regulating membrane fluidity under cold stress to promote the metabolic process of microorganisms; some pigments can reduce the damage caused by ultraviolet radiation, superoxide and nitrogen reactions to microorganisms; some pigments can also absorb light to improve the photosynthesis efficiency of microorganisms and promote the growth and reproduction of microorganisms; some pigments can even act as antibiotics to regulate the microbial community.
Microorganisms produce a variety of functionally rich pigments
1. Carotenoids
Carotenoids are organic fat-soluble pigments from groups of isoprenoids that mostly appear yellow, orange, or red in nature. According to the structural characteristics, carotenoids can be divided into three categories:
(i) Carotene, a class of hydroxyl compounds such as lycopene, β-carotene, γ-carotene, etc.;
(ii)Lutein, is a non-acidic oxygen derivative of carotene, such as astaxanthin, zeaxanthin, cryptoxanthin, etc
(iii.) Carotenoid acid, is a carboxylic acid derivative of carrots, such as saffron, annatto, etc.
Carotenoids were a secondary pigment of chlorophyll during the emergence of early life, but at the same time they can also collect energy from the wider visible spectrum to increase photosynthetic efficiency. In addition, some microbial production of carotenoids can also protect themselves from the effects of ultraviolet radiation, astaxanthin is one of them, some time ago reported in antarctic "watermelon snow" is because of the greenhouse effect of the Formation of the Antarctic ozone hole led to an increase in ultraviolet radiation, so that Antarctic microorganisms in order to protect themselves from ultraviolet radiation damage and a large number of red astaxanthin.
▲ Antarctic "watermelon snow" - Antarctic microorganisms in order to protect themselves from ultraviolet rays and a large number of red astaxanthin phenomenon
(Source: Network)
2. Algal bile protein
Phycobiliprotein is a protein that covalently binds to cysteine residues through thioether bonds and can be divided into phycocyanin (PC), phycoerythrin (PE) and allophycocyanin (APC), which appear blue, red and green in nature, respectively.
▲ A type of phycocyanin
A large number of research data show that algal biliary protein is usually produced by algal microorganisms, which is a type of pigment necessary for algae to improve light utilization, and plays a vital role in promoting the metabolism of algal microorganisms. In addition, algal biliary protein plays a non-negligible role in algae resistance to extreme environments.
3. Melanin
Melanin is a dark bio-high molecular weight pigment that usually appears dark green to brown or completely black in nature. Melanin should be one of the pigments we are most familiar with, and in addition to some microorganisms that can be produced, it is also widely present in our skin, hair, feathers, scales, eyes, and some linings.
Melanin production and ultraviolet and visible light irradiation resistance, oxidation and reducing agent protection, cell wall enzyme attack resistance, antiviral activity and environmental stress under the survival rate and competitiveness of the enhancement are inseparable, melanin-producing microorganisms in addition to Antarctica, usually distributed in high radiation environment, space station, reactor cooling water and other extreme, harsh environment, providing a strong protection for organisms.
4. Flavonoids
Flavonoids (yellow) are a class of secondary metabolites with a general structure of a 15-carbon skeleton, which can be divided into chalcones, flavonoids, isoflavones, flavonols, flavonoids and isoflavone compounds and other subclasses of products, which are usually yellow in nature.
▲ A flavonoid substance
Flavonoids have been recognized as important signaling molecules in the interaction between microorganisms and plants, which contribute to the "phytobacterial exchange" in the Antarctic environment, such as when plants are exposed to ultraviolet radiation, microorganisms can induce chemical changes, increase carbohydrates, carboxylic acids, flavonoids, etc., and enhance the resistance of plants to the harsh environment outside.
5. Pseudoglucoidin
Pseudo-dencoidin (Scytonemin) is a small hydrophobic alkaloid secondary metabolite that appears yellow-brown in nature.
Produced by cyanobacteria that normally inhabit terrestrial, freshwater, and coastal environments that are highly sunlight-exposed, pseudocoidal is a highly potent protective biomolecule that filters harmful ultraviolet radiation while also assisting cyanobacteria in photosynthesis.
epilogue
Microbes produce pigments that are far more than we see, and their functions cannot be fully summarized, so we should discover more pigments and discover more functions. For Antarctica, we initially have the impression of snowy white, but in fact there are various microorganisms modifying this "white world". Pigment production is a common feature of microorganisms, the identification of Antarctic pigment-producing microorganisms has been reported for a long time, they are considered to be a palette for drawing white canvases, unfortunately, the knowledge about the ecological role of Antarctic microbial pigments has not been properly applied. Therefore, we need to use the biological value they create to promote the development of related industries to improve our living standards.
Wei BoLai has always been committed to the study of pigments, launched a new type of natural blue pigment - valley blue, to achieve grain as raw material biosynthesis, with natural degradable, usable, natural bacteriostatic and other characteristics, to meet the application requirements of many fields, and has been applied to the lining, tableware and other daily products of color, according to the concentration of pigment solution to control the shade of color, reflecting the use of natural pigment value.
▲ Valley blue and some of its applications
Resources:
Juan José Marizcurrena, María Fernanda Cerdá, Alem D , et al. Living with Pigments: The Colour Palette of Antarctic Life[M]. The Ecological Role of Micro-organisms in the Antarctic Environment. 2019.
Cover: A cropped combination derived from a web image
(The content of the article is translated from the above references, and the content of the literature has been supplemented to a certain extent, if there are deficiencies, welcome to correct)