''Malassezia'' (formerly known as ''Pityrosporum'') is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
. It is the sole genus in
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Malasseziaceae, which is the only family in
order Malasseziales, itself the single member of
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differentl ...
Malasseziomycetes.
''Malassezia'' species are naturally found on the skin surfaces of many animals, including humans. In occasional
opportunistic infection
An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immune ...
s, some species can cause
hypopigmentation
Hypopigmentation is characterized specifically as an area of skin becoming lighter than the baseline skin color, but not completely devoid of pigment. This is not to be confused with depigmentation, which is characterized as the absence of all pi ...
or
hyperpigmentation
Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.
Causes
Hyperpigmentation can be caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris.James, William; Ber ...
on the trunk and other locations in humans.
Allergy test
Allergy testing can help confirm or rule out allergies and consequently reduce adverse reactions and limit unnecessary avoidance and medications.Boyce, J ''et al''., "Guidelines for the Diagnosis and Management of Food Allergy in the United States: ...
s for these fungi are available.
Systematics
![Pityrosporum folliculitis 2](https://upload.wikimedia.org/wikipedia/commons/d/d1/Pityrosporum_folliculitis_2.jpg)
Due to progressive changes in their nomenclature, some confusion exists about the naming and classification of ''Malassezia'' yeast species. Work on these yeasts has been complicated because they require specific
growth media
A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Different ...
and grow very slowly in
laboratory culture.
''Malassezia'' were originally identified by the French scientist
Louis-Charles Malassez
Louis-Charles Malassez (21 September 1842 – 22 December 1909) was a French anatomist and histologist born in Nevers, department of Nièvre.
He studied medicine in Paris, where he worked as an ''interne'' from 1867. He served with the 5th Ambul ...
in the late nineteenth century.
Raymond Sabouraud
Raymond Jacques Adrien Sabouraud (24 November 1864 – 4 February 1938) was a French physician born in Nantes. He specialized in dermatology and mycology, and was also an accomplished painter and sculptor.
He studied medicine in Nantes and Par ...
identified a
dandruff
Dandruff is a skin condition that mainly affects the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, ...
-causing organism in 1904 and called it "Pityrosporum malassez", honoring Malassez, but at the species level as opposed to the genus level. When it was determined that the organisms were the same, the term "Malassezia" was judged to possess
priority.
In the mid-twentieth century, it was reclassified into two species:
* ''Pityrosporum (Malassezia) ovale'', which is
lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
-dependent and found only on humans. ''P. ovale'' was later divided into two species, ''P. ovale'' and ''P. orbiculare'', but current sources consider these terms to refer to a single species of fungus, with ''M. furfur'' the preferred name.
* ''Pityrosporum (Malassezia) pachydermatis'', which is lipophilic but not lipid-dependent. It is found on the skin of most animals.
In the mid-1990s, scientists at the
Pasteur Institute
The Pasteur Institute (french: Institut Pasteur) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines f ...
in Paris, France, discovered additional species.
''Malassezia'' is the sole genus in the family Malasseziaceae, which was validated by Cvetomir Denchev and
Royall T. Moore in 2009.
The order Malasseziales had been previously proposed by Moore in 1980,
and later emended by Begerow and colleagues in 2000. At this time the order was classified as a member of
unknown
Unknown or The Unknown may refer to:
Film
* The Unknown (1915 comedy film), ''The Unknown'' (1915 comedy film), a silent boxing film
* The Unknown (1915 drama film), ''The Unknown'' (1915 drama film)
* The Unknown (1927 film), ''The Unknown'' (1 ...
class placement in the subdivision
Ustilaginomycotina
The Ustilaginomycotina is a subdivision within the division Basidiomycota of the kingdom Fungi. It consists of the classes Ustilaginomycetes and Exobasidiomycetes, and in 2014 the subdivision was reclassified and the two additional classes Malas ...
.
In 2014, Cvetomir and Teodor Denchev
circumscribed
In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius.
Not every polyg ...
the class Malasseziomycetes to contain the group.
Species
Species Fungorum
''Index Fungorum'' is an international project to index all formal names (scientific names) in the fungus kingdom. the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and the Institute of Mi ...
accepts 22 species of ''Malassezia''.
The following list gives the name of the fungus, the
taxonomic authority
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...
(those who first described the fungus, or who transferred it into ''Malassezia'' from another genus; standardized
author abbreviations are used), and the name of the organism from which the fungus was isolated, if not human.
*''
Malassezia arunalokei
''Malassezia arunalokei'' is a species of yeast-like fungus that was identified as a new to science in 2016. It has been isolated from the skin of both seborrheic dermatitis patients and healthy individuals from India. A combination of several ph ...
''
*''
Malassezia brasiliensis
''Malassezia'' (formerly known as ''Pityrosporum'') is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. ''Malassezia'' species a ...
''
– from lesions on the beak of
turquoise-fronted amazon
The turquoise-fronted amazon (''Amazona aestiva''), also called the turquoise-fronted parrot, the blue-fronted amazon and the blue-fronted parrot, is a South American species of amazon parrot and one of the most common amazon parrots kept in cap ...
parrot
*''
Malassezia caprae
''Malassezia caprae'' is a fungus first isolated in goats, which can cause opportunistic infections in animals. Its type strain
The International Code of Nomenclature of Prokaryotes (ICNP) formerly the International Code of Nomenclature of Bacte ...
''
– from skin of goat
*''
Malassezia cuniculi
''Malassezia'' (formerly known as ''Pityrosporum'') is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. ''Malassezia'' species a ...
''
– from healthy skin of external ear canal of rabbit
*''
Malassezia dermatis
''Malassezia dermatis'' is a fungus that can cause opportunistic infection
An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. The ...
''
*''
Malassezia equi''
– from skin of horse
*''
Malassezia equina
''Malassezia equina'' is a fungus first isolated in horses, which can cause opportunistic infections in animals. Its type (biology), type strain is MA146=CBS 9969. This species will not grow without any lipid supplementation. It grows slowly and ...
''
– from skin of horse
*''
Malassezia furfur
''Malassezia furfur'' (formerly known as ''Pityrosporum ovale'' in its hyphal form) is a species of yeast (a type of fungus) that is naturally found on the skin surfaces of humans and some other mammals. It is associated with a variety of dermat ...
''
*''
Malassezia globosa''
*''
Malassezia japonica
''Malassezia japonica'' is a fungus that can cause opportunistic infection
An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. The ...
''
[
*'']Malassezia muris
''Malassezia'' (formerly known as ''Pityrosporum'') is a genus of fungi. It is the sole genus in family (biology), family Malasseziaceae, which is the only family in order (biology), order Malasseziales, itself the single member of class (biology ...
'' – skin of mouse
*''Malassezia nana
''Malassezia nana'' is a fungus that can cause opportunistic infections in animals. It was first isolated from animals in Japan and Brazil. ''M. nana'' resembles '' M. dermatis'' and '' M. sympodialis'', but is distinguished from ...
'' – from discharge from ear of cat
The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
*''Malassezia obtusa
''Malassezia'' (formerly known as ''Pityrosporum'') is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. ''Malassezia'' species a ...
''
*''Malassezia ochoterenai
''Malassezia'' (formerly known as ''Pityrosporum'') is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. ''Malassezia'' species a ...
''
*'' Malassezia pachydermatis'' – from skin of Indian rhinoceros
}
The Indian rhinoceros (''Rhinoceros unicornis''), also called the Indian rhino, greater one-horned rhinoceros or great Indian rhinoceros, is a rhinoceros species native to the Indian subcontinent. It is listed as Vulnerable on the IUCN Red Li ...
*'' Malassezia psittaci'' – from lesions on the beak of blue-headed parrot
The blue-headed parrot, also known as the blue-headed pionus (''Pionus menstruus'') is a medium-sized parrot of about 27 cm in length. The body is mostly green, with a blue head and neck, and red undertail coverts. It is a resident in tropi ...
*'' Malassezia restricta''
*'' Malassezia slooffiae'' – from skin of pig
*''Malassezia sympodialis
''Malassezia sympodialis'' is a species in the genus '' Malassezia''. It is characterized by a pronounced lipophily, unilateral, percurrent or sympodial budding and an irregular, corrugated cell wall ultrastructure. It is one of the most comm ...
''
*'' Malassezia tropica''
*'' Malassezia vespertilionis'' – from vesper bats
Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat familie ...
in subfamily Myotinae
Myotinae is a subfamily of vesper bats. It contains three genera: ''Eudiscopus'', '' Myotis'', and ''Submyotodon''. Before the description of ''Submyotodon'' and analysis of its phylogenetics, as well as a phylogenetic analysis of ''Eudiscopus'', ...
*'' Malassezia yamatoensis''
Role in human diseases
Dermatitis and dandruff
Identification of ''Malassezia'' on skin has been aided by the application of molecular or DNA-based techniques. These investigations show that the ''Malassezia'' species causing most skin disease in humans, including the most common cause of dandruff
Dandruff is a skin condition that mainly affects the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, ...
and seborrhoeic dermatitis
Seborrhoeic dermatitis, sometimes inaccurately referred to as seborrhoea, is a long-term skin disorder. Symptoms include red, scaly, greasy, itchy, and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the ...
, is ''M. globosa'' (though ''M. restricta'' is also involved). The skin rash of tinea versicolor
Tinea versicolor (also pityriasis versicolor) is a condition characterized by a skin eruption on the trunk and proximal extremities. The majority of tinea versicolor is caused by the fungus '' Malassezia globosa'', although ''Malassezia furfur'' i ...
(''pityriasis versicolor'') is also due to infection by this fungus.
As the fungus requires fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers spec ...
to grow, it is most common in areas with many sebaceous gland
A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number ...
s: on the scalp, face, and upper part of the body. When the fungus grows too rapidly, the natural renewal of cells is disturbed, and dandruff appears with itching (a similar process may also occur with other fungi or bacteria).
A project in 2007 has sequenced the genome of dandruff-causing ''Malassezia globosa'' and found it to have 4,285 genes. ''M. globosa'' uses eight different types of lipase
Lipase ( ) is a family of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually tr ...
, along with three phospholipases
A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step in ...
, to break down the oils on the scalp. Any of these 11 proteins would be a suitable target for dandruff medications.
The number of specimens of ''M. globosa'' on a human head can be up to ten million.
''M. globosa'' has been predicted to have the ability to reproduce sexually, but this has not been observed.
Research
''Malassezia'' is among the many mycobiota
Mycobiota (plural noun, no singular) are a group of all the fungi present in a particular geographic region (e.g. "the mycobiota of Ireland") or habitat type (e.g. "the mycobiota of cocoa").
Human mycobiota
Mycobiota exist on the surface and in th ...
undergoing laboratory research to investigate whether it is associated with types of disease.
References
Further reading
*
{{Taxonbar, from=Q14488912
Basidiomycota
Parasitic fungi
Yeasts
Taxa described in 1889
Taxa named by Henri Ernest Baillon