Chrysosporium keratinophilum

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Chrysosporium keratinophilum
Chrysosporium keratinophilum.jpg
Scientific classification
Kingdom:
Fungi
Phylum:
Ascomycota
Class:
Euascomycetes
Order:
Onygenales
Family:
Onygenaceae
Genus:
Chrysosporium
Species:
Chrysosporium keratinophilum
Synonyms

Aphanoascus keratinophilus

Chrysosporium keratinophilum is a mold that is closely related to the dermatophytic fungi (Family Arthrodermataceae) and is mainly found in soil and the coats of wild animals to break down keratin. [1] [2] Chrysosporium keratinophilum is one of the more commonly occurring species of the genus Chrysosporium in nature. [2] It is easily detected due to its characteristic "light-bulb" shape and flat base. [3] Chrysosporium keratinophilum is most commonly found in keratin-rich, dead materials such as feathers, skin scales, hair, and hooves. [3] [4] [5] Although not identified as pathogenic, it is a regular contaminant of cutaneous specimens which leads to the common misinterpretation that this fungus is pathogenic. [6]

Contents

Description

Chrysosporium keratinophilum colonies grow rapidly at 25 °C [7] approximately 60–100 mm in 21 days. [3] Colonies can be flat or folded, dry, powdery, or velvety with a white- or cream-coloured center [3] [4] The colony surface is dotted with droplets of clear or brown exuded liquid. [3] The hyphae are septate and the conidia are hyaline, broad-based and one-celled. [3] The conidia are large, smooth to slightly rough-walled, sometimes slightly curved and occasionally septate. [4] The conidia are broadly "light-bulb" shaped with an abruptly flattened smooth base. [3] Colonies grow to about 30 mm in diameter in one week [4] [8] and are flat with a powdery to suede-like texture. [4] The colony reverse is also cream-coloured. [4] Chrysosporium keratinophilum produces abundant aleurioconidia that resemble the microconidia of dermatophytes; however, the conidia of C. keratinophilum are considerably larger. [4] Chrysosporium keratinophilum has been associated with two closely related sexual states: Aphanoascus keratinophilus and Aphanoascus fulvescens. [9]

Habitat and distribution

Aphanoascus fulvescens colony.jpg
A. fulvescens colony.
Aphanoascus fulvescens ascospores.jpg
A. fulvescens ascus (above) and ascospores (below).

Chrysosporium keratinophilum is often referred to as a keratinophilic fungus in reference to its affinity for growth on keratin-rich non-living materials such as skin scales and hairs separated from the host. [10] Chrysosporium keratinophilum produces a keratin-degrading enzyme that functions at 90 °C. [11] Its process of digestion occurs in two stages, requiring keratin to be chemically altered to a structureless form before it is digested. [1] The method of hair digestion is carried out with perforating bodies. [3] Chrysosporium spp. are asexual states of fungi in the genera Aphanoascus, Nannizziopsis, and Uncinocarpus. [7]

The fungus commonly grows on feathers, hooves, hair [10] and other dead matter. [2] It is rarely found on human skin and more commonly found in soil in temperate areas, [3] plant material, dung and on birds. [2] A study on keratinophylic fungi in the water sediments of India, by Katiyar and Kushwaha, found C. keratinophilum in sediments of catch basins and sewage sludge in India and Poland. [12] Chrysosporium keratinophilum is associated to mud sludge structure, high humidity, volatile solids, low carbon nitrogen ratios and tolerance to heavy metals. [12] Together, these give C. keratinophilum a high long-term survival probability in superficial water which may present an exposure risk, especially to people in India who bathe in these waters. [12] Apart from inhabiting water sediments, a study in Egypt identified and isolated the teleomorph of C. keratinophilium, Aphanoascus fulvescens, in half of samples gathered from floor dusts in university student housing, demonstrating its regularity in indoor environments. [13] Similarly, Bahkali and Parvez found C. keratinophilum to be widespread mold in house dust from homes in Saudi Arabia. [14] In a study of 29 sandpits from kindergarten schools and public parks in the West Bank of Jordan, Shtayeh found that over half of the fungal isolates from these materials contained fungi known to cause disease. [15] Amongst the non-pathogenic fungi found, Chrysosporium keratinophilum was the most common dermatophyte relative. [15]

A study looking at species diversity of keratin-degrading fungi in different soil types by Bohacz and Korniłłowicz-Kowalska, determined the most frequently isolated species was C. keratinophilum. [16] Together with its teleomorph, Aphanoascus fulvescens, it constituted nearly half of all isolations. [16] The frequency of this fungus was positively correlated with the content of humus, nitrogen, CaCO3 and phosphorus in the soils, [16] and the fungus demonstrated high tolerance for pH (e.g., from pH 4.5–9.5). [16] Chrysosporium keratinophilum accounted for nearly two thirds of isolations of keratinophilic fungi from phaeozem (the upper-layer, humus-rich soil horizon) and over half of keratinophilic fungi from cambisol. [16] Increased populations of C. keratinophilum were found at higher pH. [16]

Isolation

Generally, the hair-bait technique has been used to selectively isolate keratinophilic fungi from soil. [17] However, because of the poor keratinolytic activity of Chrysosporium spp., some of these fungi are not adequately isolated from soils by using this conventional technique. [17] Therefore, by utilizing the higher temperature tolerance of some Chrysosporium spp, a selective technique to isolate C. keratinophilum, C. indicum, and C. tropicum has been developed. [17] By implementing a pre-incubation treatment of keratin baited soil samples at 38 °C, the fast-growing, competitive and thermosensitive strains are eliminated, thereby reducing the competition and allowing C. keratinophilum and other thermotolerant species to continue to grow. [17]

Antagonistic activity

In a study by Singh an co-workers, eighteen fungi were isolated from soil and tested for their antagonistic interactions. [18] The maximum inhibition of Microsporum equinum, M. fulvum, M. gypseum and M. racemosum was caused by multiple fungi, including C. keratinophilum. [18] On the other hand, staling products of C. lucknowense accelerated the growth of many fungi, including C. keratinophilum. [18] Another study tested C. keratinophilum for its anti-dermatophyte activity against Trichophyton mentagrophytes and Epidermophyton flocossum. In their study, C. keratinophilum inhibited T. rubrum, T. tonsurans and T. mentagrophytes, but not M. gypseum and Microsporum nanum. [18]

Pathogenicity

Members of the genus Chrysosporium have weak pathogenic potential, with human and animal infection reported for only a few taxa. [2] Experimental studies have shown inoculation of this fungus on guinea pig skin to produce erythematous scaling lesions which disappear after 3–5 weeks; however, no apparent invasion of the hair shaft occurs. [2] In white mice, after inoculation, granulomas with necrotic centers can be observed, although conidia of the fungus appear to remain intact. [2] Chrysosporium keratinophilum is one of several soil organisms that is occasionally isolated from skin and nails. [4] Isolation of this species from clinical specimens is generally from human onychomycoses, the mycotic superficial invasion of keratinized tissue of the nail plate. [2] [5] In practice, C. keratinophilum is interpreted to be an infrequent contaminant of keratinaceous clinical specimens, such as hair, skin and nails, with no clinical significance. [6] : 198  A pathogenic role for C. keratinophilum is unlikely; however, its ability to remain viable for weeks on skin may suggest pathogenic potential. [2] [7] However, a critical component in limiting its pathogenic potential is its inability to grow at 37 °C, which is the human body temperature [19] discouraging the possibility for this fungi to be infectious to humans. The first report of onychomycosis caused by C. keratinophilum in animals was reported by Pin and his colleagues. [5] The seven Bennett's wallabies (Macropus rufogriseus rufogriseus) they observed had swollen, abnormal claws from which Chrysosporium keratinophilum was repeatedly identified in culture, suggesting that the fungus may factor in disease. [5] In another experimental study, C. keratinophilum showed pathogenic potential in the white mouse, remaining viable in the peritoneal cavity for up to two months. [20] It is possible that C. keratinophilum can cause more generalized infections in a weakened mammalian host. [20]

Biotechnological applications

Leather tanning

Chrysosporium keratinophilum produces a thermostable, keratinolytic alkaline protease when grown in medium containing keratin. [11] When grown in a medium that lacked keratin, it had no enzymatic function indicating the inducibility of the enzyme. [11] The keratinolytic protease had maximum activity at pH 9.0 and a temperature maximum of 90 °C, whereas many other fungi, such as T. mentagraphytes, Microsporum gypseum, T. rubrum, had maximum activity below pH 9.0. [11] Alkaline proteolytic keratinases are important for leather tanning as a ready means of removing hair from hides. [11]

Bioremediation

Waste removal from slaughterhouses is sometimes ploughed into nearby fields becoming a potential health risk since controlled keratin decomposition by anaerobic bacteria produces large quantities of hydrogen sulfide and ammonia. [21] Current studies are demonstrating the usefulness of the proteases produced by C. keratinophilum in bioremediation of this keratinic waste. [21]

Caffeine degradation

In another study comparing caffeine degradation by four different fungi, Nayak and her colleagues found that C, keratinophilum produces the highest rate of caffeine degradation both in the presence and absence of a nitrogen source. [22] This finding suggests that C. keratinophilum may have commercial use for the decaffeination of coffee pulp, and in the process, it could provide nutrient supplement for animal feed or improved substrates for bioethanol production. [22]

Related Research Articles

Dermatophyte is a common label for a group of fungus of Arthrodermataceae that commonly causes skin disease in animals and humans. Traditionally, these anamorphic mold genera are: Microsporum, Epidermophyton and Trichophyton. There are about 40 species in these three genera. Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the Ascomycota. As of 2019 a total of nine genera are identified and new phylogenetic taxonomy has been proposed.

<span class="mw-page-title-main">Tinea capitis</span> Cutaneous fungal infection of the scalp

Tinea capitis is a cutaneous fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the genera Trichophyton and Microsporum that invade the hair shaft. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern, that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often boys than girls.

<span class="mw-page-title-main">Dermatophytosis</span> Fungal infection of the skin

Dermatophytosis, also known as tinea and ringworm, is a fungal infection of the skin, that may affect skin, hair, and nails. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. The types of dermatophytosis are typically named for area of the body that they affect. Multiple areas can be affected at a given time.

Geomyces is a genus of filamentous fungi in the family Myxotrichaceae. Members of the genus are widespread in distribution, especially in northern temperate regions. Known to be psychrotolerant and associated with Arctic permafrost soils, they are equally prevalent in the air of domestic dwellings, and children's sandpits. Species of Geomyces have previously been placed in the genus Chrysosporium.

<i>Microsporum gypseum</i> Species of fungus

Microsporum gypseum is a soil-associated dermatophyte that occasionally is known to colonise and infect the upper dead layers of the skin of mammals. The name refers to an asexual "form-taxon" that has been associated with four related biological species of fungi: the pathogenic taxa Arthroderma incurvatum, A. gypsea, A. fulva and the non-pathogenic saprotroph A. corniculata. More recent studies have restricted M. gypseum to two teleomorphic species A. gypseum and A. incurvatum. The conidial states of A. fulva and A. corniculata have been assigned to M. fulvum and M. boullardii. Because the anamorphic states of these fungi are so similar, they can be identified reliably only by mating. Two mating strains have been discovered, "+" and "–". The classification of this species has been based on the characteristically rough-walled, blunt, club-shaped, multicelled macroconidia. Synonyms include Achorion gypseum, Microsporum flavescens, M. scorteum, and M. xanthodes. There has been past nomenclatural confusion in the usage of the generic names Microsporum and Microsporon.

Keratinases are proteolytic enzymes that digest keratin.

<i>Microsporum canis</i> Species of fungus

Microsporum canis is a pathogenic, asexual fungus in the phylum Ascomycota that infects the upper, dead layers of skin on domesticated cats, and occasionally dogs and humans. The species has a worldwide distribution.

<i>Chlamydosauromyces</i> Genus of fungi

Chlamydosauromyces punctatus is the sole species in the monotypic genus of fungi, Chlamydosauromyces in the family, Onygenaceae. It was found in the skin shed from frilled lizard. This fungus is mesophilic and digests hair. It reproduces both sexually and asexually. The fungus has so far not been reported to be pathogenic.

Microsporum nanum is a pathogenic fungus in the family Arthrodermataceae. It is a type of dermatophyte that causes infection in dead keratinized tissues such as skin, hair, and nails. Microsporum nanum is found worldwide and is both zoophilic and geophilic. Animals such as pigs and sheep are the natural hosts for the fungus; however, infection of humans is also possible. Majority of the human cases reported are associated with pig farming. The fungus can invade the skin of the host; if it is scratched off by the infected animal, the fungus is still capable of reproducing in soil.

<i>Aphanoascus fulvescens</i> Species of fungus

Aphanoascus fulvescens is a mould fungus that behaves as a keratinophilic saprotroph and belongs to the Ascomycota. It is readily isolated from soil and dung containing keratin-rich tissues that have been separated from their animal hosts. This organism, distributed worldwide, is most commonly found in areas of temperate climate, in keeping with its optimal growth temperature of 28 °C (82 °F). While A. fulvescens is recognized as a geophilic fungal species, it is also a facultative opportunistic pathogen. Although it is not a dermatophyte, A. fulvescens has occasionally been shown to cause onychomycosis infections in humans. Its recognition in the laboratory is clinically important for correct diagnosis and treatment of human dermal infections.

<i>Microsporum gallinae</i> Species of fungus

Microsporum gallinae is a fungus of the genus Microsporum that causes dermatophytosis, commonly known as ringworm. Chickens represent the host population of Microsporum gallinae but its opportunistic nature allows it to enter other populations of fowl, mice, squirrels, cats, dogs and monkeys. Human cases of M. gallinae are rare, and usually mild, non-life-threatening superficial infections.

Nannizziopsis vreisii is a keratinophilic microfungus in the Family Onygenaceae of the order Onygenales. Also included in this family are dematophytes and saprophytic species. While the ecology of N. vriessi is not well known, there has been several studies which identifies the Chrysosporium anamorph of N. vriesii as a causal agent of skin lesions in reptiles across several regions. This species is usually identified under a microscope by its white ascomata, and hyaline and globose ascospores. Like many other fungi, N. vreisii has a sexual and asexual state, the asexual states are classified as the genus Chryososporium, Malbranchea or Sporendonema.

<i>Geomyces pannorum</i> Species of fungus

Geomyces pannorum is a yellow-brown filamentous fungus of the phylum Ascomycota commonly found in cold soil environments including the permafrost of the Northern hemisphere. A ubiquitous soil fungus, it is the most common species of the genus Geomyces; which also includes G. vinaceus and G. asperulatus. Geomyces pannorum has been identified as an agent of disfigurement of pigments used in the 15,000-year-old paintings on the walls of the Lascaux caves of France. Strains of Geomyces have been recovered from the Alaskan Fox Permafrost Tunnel and radiocarbon dated to between 14,000 and 30,000 years old.

<i>Trichophyton verrucosum</i> Species of fungus

Trichophyton verrucosum, commonly known as the cattle ringworm fungus, is a dermatophyte largely responsible for fungal skin disease in cattle, but is also a common cause of ringworm in donkeys, dogs, goat, sheep, and horses. It has a worldwide distribution, however human infection is more common in rural areas where contact with animals is more frequent, and can cause severe inflammation of the afflicted region. Trichophyton verrucosum was first described by Emile Bodin in 1902.

<i>Epidermophyton floccosum</i> Species of fungus

Epidermophyton floccosum is a filamentous fungus that causes skin and nail infections in humans. This anthropophilic dermatophyte can lead to diseases such as tinea pedis, tinea cruris, tinea corporis and onychomycosis. Diagnostic approaches of the fungal infection include physical examination, culture testing, and molecular detection. Topical antifungal treatment, such as the use of terbinafine, itraconazole, voriconazole, and ketoconazole, is often effective.

<i>Keratinophyton durum</i> Species of fungus

Keratinophyton durum is a keratinophilic fungus, that grows on keratin found in decomposing or shed animal hair and bird feathers. Various studies conducted in Canada, Japan, India, Spain, Poland, Ivory Coast and Iraq have isolated this fungus from decomposing animal hair and bird feathers using SDA and hair-bait technique. Presence of fungus in soil sediments and their ability to decompose hairs make them a potential human pathogen.

<i>Ctenomyces serratus</i> Species of fungus

Ctenomyces serratus is a keratinophilic fungal soil saprotroph classified by the German mycologist, Michael Emil Eduard Eidam in 1880, who found it growing on an old decayed feather. Many accounts have shown that it has a global distribution, having been isolated in select soils as well as on feathers and other substrates with high keratin content. It has also been found in indoor dust of hospitals and houses in Kanpur, Northern India and as a common keratinophilic soil fungus in urban Berlin. This species has been associated with nail infections in humans as well as skin lesions and slower hair growth in guinea pigs.

Apinisia keratinophila, formerly Myriodontium keratinophilum, is a fungus widespread in nature, most abundantly found in keratin-rich environments such as feathers, nails and hair. Despite its ability to colonize keratinous surfaces of human body, the species has been known to be non-pathogenic in man and is phylogentically distant to other human pathogenic species, such as anthropophilic dermatophytes. However, its occasional isolation from clinical specimens along with its keratinolytic properties suggest the possibility it may contribute to disease.

Microsporum fulvum is a wildly-distributed dermatophyte species in the Fungi Kingdom. It is known to be a close relative to other dermatophytes such as Trichophyton andEpidermophyton. The fungus is common within soil environments and grows well on keratinized material, such as hair, nails and dead skin. It is recognized as an opportunistic fungal pathogen capable of causing cutaneous mycoses in humans and animals. Originally, the fungus was thought to be Microsporum gypseum until enhanced genetic examination separated the two as distinct species in 1963.

Auxarthron californiense is a fungus within the family Onygenaceae family and one of the type species of the genus Auxarthron. A. californiense is generally distributed around the world and it is frequently found on dung and in soil near the entrances of animal burrows.

References

  1. 1 2 English, Mary P. (1969). "Destruction of hair by CHrysosporium Keratinophilum". Transactions of the British Mycological Society. 52 (2): 247–255. doi:10.1016/S0007-1536(69)80037-9.
  2. 1 2 3 4 5 6 7 8 9 Chabasse, D.; Gentile, L.; Bouchara, J. -Ph. (1 June 1989). "Pathogenicity of some chrysosporium species isolated in France". Mycopathologia. 106 (3): 171–177. doi:10.1007/BF00443059.
  3. 1 2 3 4 5 6 7 8 9 de Hoog, G. S. (2000). Atlas of clinical fungi (2. ed.). Utrecht: Centraalbureau voor Schimmelcultures [u.a.] ISBN   978-9070351434.
  4. 1 2 3 4 5 6 7 8 Campbell, C.K., Johnson, E.M., and Warnock, D.W. (7 May 2013). Identification of pathogenic fungi (2nd ed.). Chichester: Wiley-Blackwell. ISBN   978-1444330700.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. 1 2 3 4 Pin, Didier; Vidémont, Emilie; Derian-Autier, Dominique; Guillot, Jacques; Plouzeau, Eric (1 March 2011). "First Description of Onychomycosis Caused by Chrysosporium keratinophilum in Captive Bennett's Wallabies (Macropus rufogriseus rufogriseus)". Journal of Zoo and Wildlife Medicine. 42 (1): 156–159. doi:10.1638/2010-0129.1. PMID   22946390.
  6. 1 2 Sigler, Lynne (2003). Pathogenic fungi in humans and animals (2. ed.). New York [u.a.]: Dekker. p. 198. ISBN   9780824706838.
  7. 1 2 3 "Chrysosporium spp". Doctor Fungus. Archived from the original on 24 November 2013. Retrieved 17 October 2013.
  8. ↑ Chabasse, D. (March 1988). "Taxonomic study of keratinophilic fungi isolated from soil and some mammals in France". Mycopathologia. 101 (3): 133–140. doi:10.1007/BF00437030.
  9. ↑ "Synonym and Classification Data for Aphanoascus spp". Doctor Fungus. Archived from the original on 19 October 2013. Retrieved 17 October 2013.
  10. 1 2 "Fungal Infections of the Skin and Skin structures". Doctor Fungus. Archived from the original on 24 November 2013. Retrieved 17 October 2013.
  11. 1 2 3 4 5 Dozie, I. N. S.; Okeke, C. N.; Unaeze, N. C. (1 September 1994). "A thermostable, alkaline-active, keratinolytic proteinase from chrysosporium keratinophilum". World Journal of Microbiology & Biotechnology. 10 (5): 563–567. doi:10.1007/BF00367668. PMID   24421135.
  12. 1 2 3 Katiyar, Sarika; Kushwaha, R. K. S. (1 January 2001). "Human hair colonizing fungi in water sediments of India". Mycopathologia. 152 (2): 81–84. doi:10.1023/A:1012483907263.
  13. ↑ Maghraby, Thanaa A.; Gherbawy, Youssuf A. M. H.; Hussein, Mohamed A. (22 April 2008). "Keratinophilic fungi inhabiting floor dusts of student houses at the South Valley University in Egypt". Aerobiologia. 24 (2): 99–106. doi:10.1007/s10453-008-9089-z.
  14. ↑ Bahkali, A; Parvez (August 1999). "<tocheading>Original Articles</tocheading>". Mycoses. 42 (4): 339–343. doi:10.1046/j.1439-0507.1999.00457.x.
  15. 1 2 Ali-Shtayeh, M. S. (September 1988). "Keratinophilic fungi isolated from children's sandpits in the Nablus area, West Bank of Jordan". Mycopathologia. 103 (3): 141–146. doi:10.1007/BF00436812.
  16. 1 2 3 4 5 6 Bohacz, Justyna; Korniłłowicz-Kowalska, Teresa (10 February 2012). "Species diversity of keratinophilic fungi in various soil types". Central European Journal of Biology. 7 (2): 259–266. doi: 10.2478/s11535-012-0008-5 .
  17. 1 2 3 4 Garg, A. P. (24 April 2009). "A selective technique for isolation of three species of Chrysosporium from soils". Mycoses. 35 (3–4): 95–97. doi:10.1111/j.1439-0507.1992.tb00826.x.
  18. 1 2 3 4 Singh, I.; Dixit, A. K.; Kushwaha, R. K. S. (January 2010). "Antagonism of Microsporum species by soil fungi". Mycoses. 53 (1): 32–39. doi:10.1111/j.1439-0507.2008.01656.x. PMID   19207833.
  19. ↑ Kane, Julius (1997). Laboratory handbook of dermatophytes : a clinical guide and laboratory handbook of dermatophytes and other filamentous fungi from skin, hair, and nails. Belmont, CA: Star Pub. ISBN   978-0898631579.
  20. 1 2 Hubalek, Z.; Hornich, M. (1977). "Experimental infection of white mouse with chrysosporium and paecilomyces". Mycopathologia. 62 (3): 173–178. doi:10.1007/BF00444111.
  21. 1 2 Singh, Chandra Jeet (1 January 2003). "Optimization of an extracellular protease of Chrysosporium keratinophilum and its potential in bioremediation of keratinic wastes". Mycopathologia. 156 (3): 151–156. doi:10.1023/A:1023395409746.
  22. 1 2 Nayak, Vibha; Pai, Pooja V.; Pai, Ashwini; Pai, Supriya; Sushma, Y. D.; Rao, C. Vaman (3 April 2013). "A Comparative Study of Caffeine Degradation by Four Different Fungi". Bioremediation Journal. 17 (2): 79–85. doi:10.1080/10889868.2012.751960.
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