From: Treseder KK, Lennon JT. 2015. Fungal traits that drive ecosystem dynamics on land. Microbiology and Molecular Biology Reviews 79:243-262.
Melanin is a condensed, randomly-arrayed, aromatic pigment that is located in the cell wall or extracellular matrix of fungi (Bell and Wheeler 1986, Butler and Day 1998, Free 2013). It broadly protects fungi from an array of environmental stresses, including extreme heat and cold, drought, UV radiation, high salinity, heavy metals, and anthropogenic pollutants (Kul’ko and Marfenina 1998, Gunde-Cimerman et al. 2000, Marfenina et al. 2002, Gorbushina et al. 2008, Selbmann et al. 2011, Sterflinger et al. 2012, Gessler et al. 2014). As a result, melanized fungi are often disproportionately represented in extreme environments such as the Antarctic (Vlasov et al. 2006, Onofri et al. 2007). Many melanized fungi belong to the Dothideomycetes or Chaetothyriales within the Ascomycota (de Hoog 2014, Gessler et al. 2014). They also include members of the yeast (e.g., Gunde-Cimerman et al. 2011), mycorrhizal (e.g., Zarivi et al. 2011, Koide et al. 2014), and free-living filamentous groups (e.g., Kroken et al. 2003, Free 2013).
Melanin resists decomposition, likely owing to its complex, aromatic structure (Malik and Haider 1982). As a result, tissues of melanized fungi are particularly recalcitrant (Linhares and Martin 1978, Martin and Haider 1986, Fernandez and Koide 2014). Accordingly, it has been suggested that melanin contributes to C storage in soils (Six et al. 2006), eventually accumulating as humic material (Linhares and Martin 1978, Saiz-Jimenez 1994, Butler and Day 1998). In consideration of these properties, Koide et al. (2014) proposed melanin production as a fungal trait that could form a direct link between environmental stress and ecosystem function.
Fungal genes for melanin synthesis
Bell, A. A. and M. H. Wheeler. 1986. Biosynthesis and functions of fungal melanins. Annu Rev Phytopathol 24:411-451.
Butler, M. J. and A. W. Day. 1998. Fungal melanins: a review. Canadian Journal of Microbiology 44:1115-1136.
de Hoog, G. S. 2014. Ecology and phylogeny of black yeast-like fungi: diversity in unexplored habitats. Fungal Diversity 65:1-2.
Fernandez, C. W. and R. T. Koide. 2014. Initial melanin and nitrogen concentrations control the decomposition of ectomycorrhizal fungal litter. Soil Biol Biochem 77:150-157.
Free, S. J. 2013. Fungal cell wall organization and biosynthesis. Pages 33-82 in T. Friedmann, J. C. Dunlap, and S. F. Goodwin, editors. Advances in Genetics, Vol 81. Elsevier Academic Press Inc, San Diego.
Gessler, N. N., A. S. Egorova, and T. A. Belozerskaya. 2014. Melanin pigments of fungi under extreme environmental conditions (Review). Applied Biochemistry and Microbiology 50:105-113.
Gorbushina, A. A., E. R. Kotlova, and O. A. Sherstneva. 2008. Cellular responses of microcolonial rock fungi to long-term desiccation and subsequent rehydration. Stud Mycol 61:91-97.
Gunde-Cimerman, N., M. Grube, and G. S. de Hoog. 2011. The emerging potential of melanized fungi: black yeast between beauty and the beast. Fungal Biol 115:935-936.
Gunde-Cimerman, N., P. Zalar, S. de Hoog, and A. Plemenitas. 2000. Hypersaline waters in salterns – natural ecological niches for halophilic black yeasts. Fems Microbiology Ecology 32:235-240.
Koide, R. T., C. Fernandez, and G. Malcolm. 2014. Determining place and process: functional traits of ectomycorrhizal fungi that affect both community structure and ecosystem function. New Phytol 201:433-439.
Kroken, S., N. L. Glass, J. W. Taylor, O. C. Yoder, and B. G. Turgeon. 2003. Phylogenomic analysis of type I polyketide synthase genes in pathogenic and saprobic ascomycetes. Proc Natl Acad Sci U S A 100:15670-15675.
Kul’ko, A. B. and O. E. Marfenina. 1998. Species composition of microscopic fungi in urban snow cover. Microbiology 67:470-472.
Linhares, L. F. and J. P. Martin. 1978. Decomposition in soil of humic acid-type polymers (melanins) of Eurotium echinulatum, Aspergillus glaucus sp and other fungi. Soil Sci Soc Am J 42:738-743.
Malik, K. A. and K. Haider. 1982. Decomposition of 14C-labeled melanoid fungal residues in marginally sodic soil. Soil Biol Biochem 14:457-460.
Marfenina, O. E., A. B. Kul’ko, A. E. Ivanova, and M. V. Sogonov. 2002. The microfungal communities in the urban outdoor environment. Mikologiya i Fitopatologiya 36:22-32.
Martin, J. P. and K. Haider. 1986. Influence of mineral colloids on turnover rates of soil organic carbon.in P. M. Huang and M. Shnitzer, editors. Interactions of soil minerals with natural organics and microbes. SSSA Special Pub. No. 17. SSSA, Madison, WI.
Onofri, S., L. Seltimann, G. S. de Hoog, M. Grube, D. Barreca, S. Ruisi, and L. Zucconi. 2007. Evolution and adaptation of fungi at boundaries of life. Advances in Space Research 40:1657-1664.
Saiz-Jimenez, C. 1994. Analytical pyrolysis of humic substances: Pitfalls, limitations, and possible solutions. Environmental Science & Technology 28:1773-1780.
Selbmann, L., D. Isola, L. Zucconi, and S. Onofri. 2011. Resistance to UV-B induced DNA damage in extreme-tolerant cryptoendolithic Antarctic fungi: detection by PCR assays. Fungal Biol 115:937-944.
Six, J., S. D. Frey, R. K. Thiet, and K. M. Batten. 2006. Bacterial and fungal contributions to carbon sequestration in agroecosystems. Soil Sci Soc Am J 70:555-569.
Sterflinger, K., D. Tesei, and K. Zakharova. 2012. Fungi in hot and cold deserts with particular reference to microcolonial fungi. Fungal Ecology 5:453-462.
Vlasov, D. Y., G. A. Gorbunov, V. A. Krylenkov, V. V. Lukin, E. V. Safronova, and Y. I. Senkevich. 2006. Micromycetes from the polar stations area in western Antarctica. Mikologiya i Fitopatologiya 40:202-211.
Zarivi, O., A. Bonfigli, S. Colafarina, P. Aimola, A. M. Ragnelli, G. Pacioni, and M. Miranda. 2011. Tyrosinase expression during black truffle development: From free living mycelium to ripe fruit body. Phytochemistry 72:2317-2324.