Crepidotus variabilis CBS 506.95 v1.0
Photo of Crepidotus variabilis CBS 506.95 v1.0
Photo by José María Barrasa

Crepidotus variabilis (Pers.) P. Kumm is a small agaric commonly known as “Variable Osterling”. This is one of the most common saprobic species growing on wood debris in forest ecosystems. It usually fruits on fallen twigs and dead wood of deciduous trees and, less frequently, on conifers. It is widespread throughout the world, especially in Northern temperate and South American regions, from spring to autumn but even in winter. Fruit bodies are characterized by their white, sessile, kidney-shaped and hairy cap with frequently lobed margin and whitish gills that becomes ochraceous with age (Aime, 2001).

C. variabilis belongs to the saprobic family Crepidotaceae within the Agaricoid clade (Matheny et al., 2006). In order to complete the genomic analysis within the large diversity of saprobic families of Agaricales, C. variabilis represents the only member of this family proposed for sequencing in the JGI project CSP15-1609 aimed to analyze 32 genomes of Agaricales species. The knowledge of the C. variabilis genome sequence will allow to compare its lignocellulolytic enzymes with those of the other white-rot wood Agaricales both proposed to be sequenced in this project (such as Cyathus striatus, Nidulariaceae and Oudemansiella mucida, Physalacriaceae) and already sequenced at JGI (such as Pleurotus ostreatus, Pleurotaceae and Galerina marginata, Cortinariaceae). Moreover, it will be useful for comparison with the genomes of the brown-rot wood Agaricales (such as Fistulina hepatica, Fistulinaceae) and Polyporales (such as Fomitopsis pinicola) also sequenced at JGI.

Together with Ceriporiopsis subvermispora (Polyporales), C. variabilis has been reported to be one of the most efficient basidiomycetes in lignin degradation, producing the highest cellulose enrichments, as revealed by Py-GC/MS analysis of decayed hardwood (Martínez et al., 2005). Crude ligninolytic enzymes (where laccase and peroxidase activities were detected) of a C. variabilis strain inhabiting marine ecosystems (mangrove forests of coastal Tanzania), was investigated for their ability to degrade aromatic compounds, such as Remazol brilliant blue-R dye, phenol and pyrogallol (Mtui, 2007). Furthermore, terrestrial strains of C. variabilis have been reported to be able to degrade lignin (18% of the initial content) and lipophilic extractives (82 and 89% of initial content of free and sterified sterols respectively) in Eycalyptus globulus wood under solid state fermentation conditions. These studies suggest C. variabilis as one of the most promising white-rot basidiomycetes for biological control of pitch deposition in E. globulus pulp (Gutierrez et al., 1999; Martínez et al., 1999).

References

Aime, M.C. 2001. Biosystematics studies in Crepidotus and Crepidotaceae (Basidiomycetes, Agaricales) PhD Dissertation, Virginia State University. 194pp.

Gutiérrez, A., del Río, J.C., Martínez., M.J. and Martínez, A.T. 1999. Fungal degradation of lipophilic extractives in Eucalyptus globulus. Appl. Environ. Microb. 65: 1367-1371.

Martínez., M.J., Barrasa, J.M., Gutiérrez, A., del Río, J.C. and Martínez, A.T. 1999. Fungal screening for biological removal of extractives from Eucalyptus globulus wood. Can. J. Bot., 77: 1513-1522.

Martínez, A.T., Speranza, M., Ruiz-Dueñas, F.J., Ferreira, P., Camarero, S., Guillén, F., Martínez., M.J, Gutiérrez, A. and del Río, J.C. 2005. Biodegradation of lignocellulosics: microbial, chemical, and enzymatic aspects of the fungal attack of lignin. Int. Microbiol. 8: 195-204.

Matheny, P.B., Curtis, J.M., Hofstetter, V., Aime, M.C., Moncalvo, J.M., Ge, Z.W., Yang, Z.L., Slot, J.C., Ammirati, J.F., Baroni, T.J., Bougher, N.L., Hughes, K.W., Lodge, D.J., Kerrigan, R.W., Seidl, M.T., Aanen, D.K., DeNitis, M., Daniele, G.M., Desjardin, D.E., Kropp, B.R., Norvell, L.L., Parker, A., Vellinga, E.C., Vilgalys, R., Hibbett, D.S., 2006. Major clades of Agaricales: a multilocus phylogenetic overview. Mycologia 98, 982-995.

Mtui, G. 2007. Characteristics and dyes biodegradation potential of crude ligninolytic enzymes from white-rot fungus Crepidotus variabilis isolated in coastal Tanzania. Tanz. J. Sci. 33: 79-91.