''Aureobasidium melanogenum'', formerly known as ''

Aureobasidium pullulans ''Aureobasidium pullulans'' is a ubiquitous and generalistic black, yeast-like fungus that can be found in different environments (e.g. soil, water, air and limestone). It is well known as a naturally occurring epiphyte or endophyte of a wide ra ...

'' var. ''melanogenum'' is a ubiquitous black, yeast-like fungus that is found mainly in freshwater habitats. The species also includes strains causing human infections, which were previously classified as ''A. pullulans''. It was named due to abundant melanin production and accumulation in the cell walls, which leads to dark green, brown or black appearance of the cells and

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

The species was established when the

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

s of the four former varieties of ''

'' were sequenced and the large differences between them were discovered. The species tolerates up to 10% of

NaCl Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g/ ...

and grows between 10 °C and 35 °C.

Colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

on malt extract agar on average grow to 25 mm in 7 days (at 25 °C), appearing smooth and slimy due to abundant sporulation and EPS formation. In two weeks the colonies become green to black due to the production of

melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

. Melanin is produced during the production of

pullulan Pullulan is a polysaccharide polymer consisting of maltotriose units, also known as α-1,4- ;α-1,6- glucan'. Three glucose units in maltotriose are connected by an α-1,4 glycosidic bond, whereas consecutive maltotriose units are connected to e ...

, a polysaccharide partly responsible of the biofilm formation. Aerial

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates ...

is generally absent (with exceptions). Frequently both

and

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

-like cells are present. The genome of ''A. melanogenum'' (as well as other closely related species) contains unusually high numbers of genes for extracellular enzymes for carbohydrate degradation (

CAZy CAZy is a database of Carbohydrate-Active enZYmes (CAZymes). The database contains a classification and associated information about enzymes involved in the synthesis, metabolism, and recognition of complex carbohydrates, i.e. disaccharides, olig ...

) and

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...

s, MFS

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

sugar transporters, and

alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...

cation transporters (or

ion transporters An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

). Genes presumably involved in the synthesis of the biotechnologically important polysaccharide

and

siderophore Siderophores (Greek: "iron carrier") are small, high-affinity iron- chelating compounds that are secreted by microorganisms such as bacteria and fungi. They help the organism accumulate iron. Although a widening range of siderophore functions is n ...

s were found, but the gene for

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

Aureobasidin A could not be identified. Genes possibly associated with the degradation of

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

and

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

compounds are also present. Due to the relatively recent redefinition of the species, most published work does not yet distinguish between the new species belonging to the previously recognised ''A. pullulans'' species complex. It is therefore not clear to what extent this knowledge is valid for ''A. melanogenum''.

References

External links

Genome Page on Mycocosm
{{Taxonbar, from=Q18355409 Yeasts Dothideales

See also

References

External links