Aspergillus unguis

Aspergillus unguis
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Eurotiales
Genus: Aspergillus
Species: A. unguis
Binomial name
Aspergillus unguis
Weill & L. Gaudin (1935)
Synonyms
  • Sterigmatocystis unguis Weill & L. Gaudin (1918)
  • Aspergillus laokiashanensis Y.K. Shih (1936)
  • Aspergillus mellinus Novobr. (1972)

Aspergillus unguis is a member of the genus Aspergillus in the phylum Ascomycota, and the asexual state (anamorph) of Emericella unguis.[1][2] Aspergillus unguis is a filamentous soil-borne fungus[3] found on decomposing plant matter and other moist substrates including with building materials and household dust.[4] Aspergillus unguis occurs mainly in tropical and suptropical soils but has also been isolated from various marine and aquatic habitats.[5] The species was first isolated in 1935 by Weill and L. Gaudin.[2] Historically, A. unguis was assigned to the A. nidulans group, a common group of soil-borne fungi due to the resemblance of its ascospores and cleistothecia to those of Emericella nidulans.[6] Aspergillus unguis is distinctive, however, in possessing spicular hyphae.[6] A number of synonyms have been collapsed into this species, including: Sterigmatocystis unguis, Aspergillus laokiashanensis and Aspergillus mellinus.[7]

Growth and morphology

Colonies typically reach up to 2 cm in diameter at 10 days incubation, growing optimally at 30 °C (86 °F).[5] A number of growth media are suitable for the cultivation of this species, including Sabouraud maltose agar, Czapek’s agar, Raulin’s agar.[5] The colonies of A. unguis are first white in colour becoming greenish or chrome green in the centre,[5] and ultimately dull brown colour similar to chocolate.[6] The dark colour is due to the presence of melanin or melanin like-pigments within the cell wall.[8] This dark brown colouration is unique to the species and has cause some researchers to include it in the dematiaceous fungi, a group of unrelated, darkly coloured moulds that includes some serious opportunistic pathogens of humans.[8] Despite its outward similarity to the dematiaceous fungi, the latter group conventionally excludes members of the order Eurotiales.

The conidiophoress are smoothed walled, non-septate, reaching 45-65 µm in length.[5] The mature sporulating heads are 250-300 µm in diameter and columnar.[5] The conidiophores terminate in hemispherical vesicles 9-12 µm, wide, that become covered by primary and secondary metulae giving rise to phialides.[6] The conidia are spherical in shape, roughly 3 µm in diameter and develop brownish vein-like structures on the spore walls over time.[5] Conidia are borne in columns at the tips of aspergilloid conidiophores.[6] The spicular hyphae of A. unguis are aseptate and become brown in colour, thick-walled and irregularly roughened and tapering with blunt apex.[6] They reach a length of 1000 µm or greater.[6]

Ecology

Aspergillus unguis is a soil-dwelling fungus that prefers high water activity (aw).

Human disease

Disease of the nail and skin caused by A. unguis has been reported.[4] This species was one of two most common fungi encountered in the homes of asthmatic children in Detroit, Michigan, reported from 72% of homes.[9] It has also been reported as a colonist of water damaged construction materials in Finland where it was found to produce the mycotoxin, sterigmatocystin, a potent carcinogen and mutagen.[10]

Metabolites

Beta-glucosidase

Production of beta-glucosidases is well known in members of the genus Aspergillus, however only few species can produce glucose tolerant isoforms. Beta-glucosidases produced by A. unguis are characteristically highly glucose-tolerant.[3] For this reason, the fungus has been investigated industrially for use in the hydrolysis of cellulose hydrolysis and biomass conversion (cellulose to glucose to fuel ethanol).[3]

Depsidones

Four bioactive, chlorinated depsidones have been isolated from strains of this species obtained from seaweed collected off the coasts of China and Thailand.[11] These compounds exhibited potent inhibitory effects against methicillin-resistant Staphylococcus aureus (MRSA), brine shrimp larvae (test for compound cytotoxicity and pesticide-ability) and the human lung tumor line A-549.[11] No activity was found against E. coli strain AB1157+; however depsidones 1, 3 & 4, and to a lesser extent 2, exhibited selective bioactivity on strain AB3027-.[11] Some compounds introduced DNA damage.[11] Only depsidone 1 showed significant anti-proliferatory activity on human cancer cells.[11] Folipastatin, another depsidone is inhibitory to phospholipase A2, an important enzyme in the lipolysis pathway that also is related to the expression of inflammatory mediators such as arachidonic acid.[12] Exposure of hypertensive rats to this compound produced an anti-inflammatory effect with mild ]]edema]] at the injection site but without an increase in blood pressure edemas on the hypertensive rats.[12]

Guisinol

Guisinol was isolated from a strain of the teleomorph, Emericella unguis derived from a mollusc collected from coastal Venezuela.[13] This compound also inhibit the growth of MRSA in vitro.[13]

Unguinol

The metabolite unguinol, produced uniuquely by A. unguis, is a growth promotor specific to monogastric animals such as chickens.[14] It also been investigated as a potential herbicide due to its ability to selectively inhibit pyruvate, phosphate dikinase (PPDK), a key enzyme in gluconeogenesis and photosynthesis.[15]

References

  1. ↑ "Catalogue of Life : Aspergillus unguis (Émile-Weill & L. Gaudin) Thom & Raper 1934". www.catalogueoflife.org. Retrieved 2015-11-16.
  2. 1 2 Malloch, David; Cain, R. F. (1972-01-01). "New species and combinations of cleistothecial Ascomycetes". Canadian Journal of Botany. 50 (1): 61–72. doi:10.1139/b72-011. ISSN 0008-4026.
  3. 1 2 3 Rajasree, Kuni Parambil; Mathew, Gincy Marina; Pandey, Ashok; Sukumaran, Rajeev Kumar (2013-06-04). "Highly glucose tolerant β-glucosidase from Aspergillus unguis: NII 08123 for enhanced hydrolysis of biomass". Journal of Industrial Microbiology & Biotechnology. 40 (9): 967–975. doi:10.1007/s10295-013-1291-5. ISSN 1367-5435.
  4. 1 2 "Aspergillosis. DermNet NZ". www.dermnetnz.org. Retrieved 2015-11-16.
  5. 1 2 3 4 5 6 7 Dodge, C.W. (1935). Medical mycology. Fungous diseases of men and other mammals. p. 637.
  6. 1 2 3 4 5 6 7 Raper1 Fennell2, K.B.1, D.I.2 (1965). The Genus Aspergillus. Williams and Wilkins. p. 686.
  7. ↑ "Aspergillus unguis". www.mycobank.org. Retrieved 2015-11-16.
  8. 1 2 Brandt, ME; Warnock, DW (November 2003). "Epidemiology, clinical manifestations, and therapy of infections caused by dematiaceous fungi.". Journal of chemotherapy (Florence, Italy). 15 Suppl 2: 36–47. doi:10.1179/joc.2003.15.supplement-2.36. PMID 14708965.
  9. ↑ Vesper, Stephen; McKinstry, Craig; Haugland, Richard; Neas, Lucas; Hudgens, Edward; Heidenfelder, Brooke; Gallagher, Jane (2008-05-01). "Higher Environmental Relative Moldiness Index (ERMIsm) values measured in Detroit homes of severely asthmatic children". Science of The Total Environment. 394 (1): 192–196. doi:10.1016/j.scitotenv.2008.01.031.
  10. ↑ Tuomi, Tapani; Reijula, Kari; Johnsson, Tom; Hemminki, Kaisa; Hintikka, Eeva-Liisa; Lindroos, Outi; Kalso, Seija; Koukila-Kähkölä, Pirkko; Mussalo-Rauhamaa, Helena (2000-05-01). "Mycotoxins in Crude Building Materials from Water-Damaged Buildings". Applied and Environmental Microbiology. 66 (5): 1899–1904. doi:10.1128/AEM.66.5.1899-1904.2000. ISSN 0099-2240. PMC 101430Freely accessible. PMID 10788357.
  11. 1 2 3 4 5 Zhang, Yi; Mu, Jun; Feng, Yan; Wen, Lixue; Han, Jinyuan (2014-04-03). "Four chlorinated depsidones from a seaweed-derived strain of Aspergillus unguis and their new biological activities". Natural Product Research. 28 (7): 503–506. doi:10.1080/14786419.2013.879305. ISSN 1478-6419. PMID 24479775.
  12. 1 2 HAMANO, KIYOSHI; KINOSHITA-OKAMI, MASAKO; HEMMI, ATSUKO; SATO, AKIRA; HISAMOTO, MARIE; MATSUDA, KEIICHI; YODA, KEIKO; HARUYAMA, HIDEYUKI; HOSOYA, TSUYOSHI. "Folipastatin, a new depsidone compound from Aspergillus unguis as an inhibitor of phospholipase A2. Taxonomy, fermentation, isolation, structure determination and biological properties.". The Journal of Antibiotics. 45 (8): 1195–1201. doi:10.7164/antibiotics.45.1195.
  13. 1 2 Nielsen, Joan; Nielsen, Per Halfdan; Frisvad, Jens C (January 1999). "Fungal depside, guisinol, from a marine derived strain of Emericella unguis". Phytochemistry. 50 (2): 263–265. doi:10.1016/S0031-9422(98)00517-2.
  14. ↑ Unguinol and analogs are animal growth permittants, retrieved 2015-11-16
  15. ↑ Motti, Cherie A.; Bourne, David G.; Burnell, James N.; Doyle, Jason R.; Haines, Dianne S.; Liptrot, Catherine H.; Llewellyn, Lyndon E.; Ludke, Shilo; Muirhead, Andrew (2007-03-15). "Screening Marine Fungi for Inhibitors of the C4 Plant Enzyme Pyruvate Phosphate Dikinase: Unguinol as a Potential Novel Herbicide Candidate". Applied and Environmental Microbiology. 73 (6): 1921–1927. doi:10.1128/AEM.02479-06. ISSN 0099-2240. PMC 1828816Freely accessible. PMID 17220253.
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