''Geotrichum candidum'' is a

fungus 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 fr ...

which is a member of the

human microbiome The human microbiome is the aggregate of all microbiota that reside on or within human tissues and biofluids along with the corresponding anatomical sites in which they reside, including the skin, mammary glands, seminal fluid, uterus, ovarian ...

, notably associated with skin,

sputum Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). In medicine, sputum samples are usually used for a naked eye examination, microbiological investigation of respiratory infections and cytological investigatio ...

, and faeces where it occurs in 25–30% of specimens. It is common in soil and has been isolated from soil collected around the world, in all continents. ''G. candidum'' is the causative agent of the human disease

geotrichosis Geotrichosis is a mycosis caused by ''Geotrichum candidum''. Human colonization and disease ''Geotrichum candidum'' is also a frequent member of the human microbiome, notably associated with skin, sputum and feces where it occurs in 25-30% of spec ...

, the plant disease sour rot which infects

citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

fruits,

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

es,

carrot The carrot ('' Daucus carota'' subsp. ''sativus'') is a root vegetable, typically orange in color, though purple, black, red, white, and yellow cultivars exist, all of which are domesticated forms of the wild carrot, ''Daucus carota'', na ...

s, and other vegetables. It can affect harvested fruit of

durian The durian (, ) is the edible fruit of several tree species belonging to the genus ''Durio''. There are 30 recognised ''Durio'' species, at least nine of which produce edible fruit. '' Durio zibethinus'', native to Borneo and Sumatra, is the on ...

s such as ''

Durio graveolens ''Durio graveolens,'' sometimes called the red-fleshed durian, orange-fleshed durian, or yellow durian, is a species of tree in the family Malvaceae. It is one of six species of durian named by Italian naturalist Odoardo Beccari. The specific ...

''. ''G. candidum'' is used widely in the production of certain dairy products including rind cheeses such as

Camembert Camembert (, also , ) is a moist, soft, creamy, surface-ripened cow's milk cheese. It was first made in the late 18th century in Camembert, Normandy, in northwest France. It is sometimes compared in look and taste to brie cheese, albeit wi ...

Saint-Nectaire Saint-Nectaire is a French cheese made in the Auvergne region of central France. The cheese has been made in Auvergne since at least the 17th century. History Up until the 17th century, the Saint-Nectaire cheese was farmstead, and mostly made ...

Reblochon Reblochon () is a soft washed-rind and smear-ripened French cheese made in the Alpine region of Haute-Savoie from raw cow's milk. It has its own AOC designation. Reblochon was first produced in the Thônes and Arly valleys, in the Aravis massi ...

, and others. The fungus can also be found in a Nordic

yogurt Yogurt (; , from tr, yoğurt, also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as ''yogurt cultures''. Fermentation of sugars in the milk by these bac ...

-like product known as

viili Viili (Finnish) is a mesophilic fermented milk product found in the Nordic countries, particularly Finland. Viili is similar to yoghurt or kefir, but when left unmixed, its texture is malleable, or "long". The metabolism of the bacteria used in t ...

where it is responsible for the product's velvety texture. In a 2001 study, ''G. candidum'' was found to consume the

polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily work ...

found in CDs. This effect was later replicated in 2021.

History

Taxonomy

The genus ''

Geotrichum Geotrichum is a genus of fungi found worldwide in soil, water, air, and sewage, as well as in plants, cereals, and dairy products; it is also commonly found in normal human flora and is isolated from sputum and feces. It was first described in ...

'' was described by

Johann Heinrich Friedrich Link Johann Heinrich Friedrich Link (2 February 1767 – 1 January 1851) was a German naturalist and botanist. Biography Link was born at Hildesheim as a son of the minister August Heinrich Link (1738–1783), who taught him love of nature throug ...

in 1809 to accommodate the species ''G. candidum'' found on decaying leaves. Since then, over 130 taxa have been described in the genus, and hundreds of synonyms have been generated. For example, ''G. candidum'' was misclassified as the ''Oidium lactis'' in much early literature. Species of ''Geotrichum'' resemble the genera ''

Trichosporon ''Trichosporon'' is a genus of anamorphic fungi in the family Trichosporonaceae. All species of ''Trichosporon'' are yeasts with no known teleomorphs (sexual states). Most are typically isolated from soil, but several species occur as a natural ...

'' and ''Protendomycopsis''; however, ''Geotrichum'' is of

ascomycetous Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

affiliation whereas the latter are members of the

Basidiomycota Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Bas ...

. Species of ''Geotrichum'' are occasionally mistaken for fast growing members of the genus '' Dipodascus'', which are characterized by irregularly branched, 10–14 μm wide

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e and the production of single-spored

asci ASCI or Asci may refer to: * Advertising Standards Council of India * Asci, the plural of ascus, in fungal anatomy * Accelerated Strategic Computing Initiative * American Society for Clinical Investigation * Argus Sour Crude Index * Association of ...

. However, unlike ''Geotrichum'', members of the genus ''Dipodascus'' lack dichotomous branching of the peripheral hyphae and their growth rates are generally less than 3 mm per day.

Phylogeny

''Galactomyces candidus'', formerly thought to be a distinct taxon, was found to be the sexual state of ''G. candidum'' using sequence-based methods ''Geotrichum candidum'' in the broad sense comprises 3

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

s, corresponding to the species ''G. candidum'', '' G. clavatum'' and '' G. fici'', all of which are thought to have pathogenic potential. Species of ''Geotrichum'' can be differentiated by sequence analysis of the nuclear ribosomal large subunit (

18S ribosomal RNA 18S ribosomal RNA (abbreviated 18S rRNA) is a part of the ribosomal RNA. The S in 18S represents Svedberg units. 18S rRNA is an SSU rRNA, a component of the eukaryotic ribosomal small subunit ( 40S). 18S rRNA is the structural RNA for the small ...

) or the

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ...

region of the nuclear ribosomal RNA gene.

Morphology

Anamorph

''G. candidum'' colonies are thin, spreading, soft, creamy and white in the

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an a ...

state. The fungus ''G. candidum'' is characterized by hyphae that appear creeping, mostly submerged and septatee. The hyphae colour appears to be

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

or lightly pigmented. When the hyphae becomes airborne it changes shape from

arthroconidia Arthroconidia are a type of fungal spore typically produced by segmentation of pre-existing fungal hyphae. Background These spores are asexual and are generally not as durable and environmentally persistent as, for instance, bacterial endospores ...

to cylindrical or barrel-shaped or ellipsoidal.

Chlamydospore A chlamydospore is the thick-walled large resting spore of several kinds of fungi, including Ascomycota such as '' Candida'', Basidiomycota such as '' Panus'', and various Mortierellales species. It is the life-stage which survives in unfavourable ...

s are subglobose, solitary, borne on undifferentiated hyphae. Blastoconidia sometimes develop on hyphae laterally.

Conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to t ...

appear arthrosporous, terminal or intercalary, aerial on an agar surface. The

conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to t ...

size ranges from 4.8 to 12.5 μm x 2.4–2.5 μm.

Teleomorph

''G. candidum'' is thought to be homothallic but most isolates are self-sterile. Sexual reproduction was first observed in strains isolated from soils in

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...

. The fungus produces globose asci that contain a single, thick walled,

uninucleate {{Short pages monitor