Hortaea werneckii

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Hortaea werneckii
Hortaea-werneckii-fungus--causes-tinea-nigra.jpg
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Capnodiales
Family: Teratosphaeriaceae
Genus: Hortaea
Species: H. werneckii
Binomial name
Hortaea werneckii
(Horta) Nishim. & Miyaji (1984)

Hortaea werneckii is a species of yeast in the family Teratosphaeriaceae.[1] It is a black yeast that is investigated for its remarkable halotolerance.[2][3] While the addition of salt to the medium is not required for its cultivation, H. werneckii can grow in close to saturated NaCl solutions.[4] To emphasize this unusually wide adaptability, and to distinguish H. werneckii from other halotolerant fungi, which have lower maximum salinity limits, some authors describe H. werneckii as "extremely halotolerant".[4]

Several salt-tolerance mechanisms of H. werneckii have been studied on molecular level.[4] For example it is known that its major compatible solutes are glycerol, erythritol, arabitol, and mannitol; melanin accumulation of the cell wall aids in retention of at least glycerol inside of the cell.[3] Several components of the high osmolarity glycerol (HOG) signalling pathway (which controls controls responses to osmotic shock) have been studied in detail and some seem to differ in function compared to their counterparts in Saccharomyces cerevisiae.[5][6][7] Adaptation to high concentrations of salt are also accompanied by changes in membrane lipid composition, mainly by increasing the unsaturation of the phospholipid fatty acids.[8][9]

H. werneckii causes a rare superficial and non-invasive skin infection Tinea nigra.[10] The typical symptoms are non-scaly, smooth, brown-black painless spots on the palms of hands and soles of feet.

The growth of H. werneckii in liquid media is often yeast-like, although it can switch to filamentous growth. The mechanism of the switch is not known. The cells appear brown because of melanin production.[3]

Whole genome sequencing of H. werneckii revealed a recent whole genome duplication, resulting in a relatively large genome (51.6 Mb) with 23333 predicted genes. Genes encoding metal cation transporters, which are thought to play a role in halotolerance, experienced several additional gene duplications at various points during their evolution. A heterothallic mating locus was found in the genome.[11]

References[edit]

  1. ^ http://www.doctorfungus.org/thefungi/hortaea.htm
  2. ^ Gunde-Cimerman N, Ramos J, Plemenitas A (2009). Halotolerant and halophilic fungi. Mycological Research 113: 1231-41. PMID: 19747974
  3. ^ a b c Kogej T, Stein M, Volkmann M, Gorbushina AA, Galinski EA, Gunde-Cimerman N (2007). Osmotic adaptation of the halophilic fungus Hortaea werneckii: role of osmolytes and melanization. Microbiology 153: 4261-73. PMID: 18048939
  4. ^ a b c Gostinčar C, Lenassi M, Gunde-Cimerman N, Plemenitaš A (2011). Fungal adaptation to extremely high salt concentrations. Advances in Applied Microbiology 77: 71-96. PMID 22050822
  5. ^ Turk, M.; Plemenitas, A. (2002). "The HOG pathway in the halophilic black yeast Hortaea werneckii: Isolation of the HOG1 homolog gene and activation of HwHog1p". FEMS microbiology letters 216 (2): 193–199. doi:10.1111/j.1574-6968.2002.tb11435.x. PMID 12435502.  edit
  6. ^ Lenassi, M.; Vaupotic, T.; Gunde-Cimerman, N.; Plemenitas, A. (2007). "The MAP kinase HwHog1 from the halophilic black yeast Hortaea werneckii: Coping with stresses in solar salterns". Saline Systems 3: 3. doi:10.1186/1746-1448-3-3. PMC 1828057. PMID 17349032.  edit
  7. ^ Fettich, M.; Lenassi, M.; Veranič, P.; Gunde-Cimerman, N.; Plemenitaš, A. (2011). "Identification and characterization of putative osmosensors, HwSho1A and HwSho1B, from the extremely halotolerant black yeast Hortaea werneckii". Fungal Genetics and Biology 48 (5): 475–484. doi:10.1016/j.fgb.2011.01.011. PMID 21281727.  edit
  8. ^ Turk, M.; Méjanelle, L.; Sentjurc, M.; Grimalt, J. O.; Gunde-Cimerman, N.; Plemenitas, A. (2003). "Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi". Extremophiles 8 (1): 53–61. doi:10.1007/s00792-003-0360-5. PMID 15064990.  edit
  9. ^ GostinäAr, C.; Turk, M.; Plemenitas, A.; Gunde-Cimerman, N. (2009). "The expressions of Δ9-, Δ12-desaturases and an elongase by the extremely halotolerant black yeastHortaea werneckiiare salt dependent". FEMS Yeast Research 9 (2): 247–256. doi:10.1111/j.1567-1364.2009.00481.x. PMID 19220869.  edit
  10. ^ Reid BJ (July 1998). "Exophiala werneckii causing tinea nigra in Scotland". Br. J. Dermatol. 139 (1): 157–8. PMID 9764175. 
  11. ^ Lenassi M, Gostinčar C, Jackman S, Turk M, Sadowski I, Nislow C, Jones S, Birol I, Gunde-Cimerman N, Plemenitaš A (2013). Whole genome duplication and enrichment of metal cation transporters revealed by de novo genome sequencing of extremely halotolerant black yeast Hortaea werneckii. PLoS ONE 8: e71328.