Lepista nuda CBS 247.69 v1.0
Photo of Lepista nuda CBS 247.69 v1.0
Photo by José María Barrasa

Lepista nuda (Bull.) Cooke is commonly known as “blewit mushroom” due to the characteristic blue-lilac color of cap, gills and stem. It is an edible saprobic fungus frequently fruiting on organic plant debris, and a common leaf litter degrader in both deciduous and coniferous forests of Northern Hemisphere. On the basis of a multilocus analysis of a six-gene region supermatrix, L. nuda is placed in the Tricholomatoid clade and Tricholomataceae family, within the order Agaricales (Matheny et al., 2006). Different nutritional strategies and ecologies have been developed in genera of the Tricholamataceae such as mycoparasitism (i.e. Collybia) or ectomycorrhizal formation (i.e. Tricholoma). Interestingly, since nitrogen is a limiting factor for wood and leaf litter carbohydrate degradation in forest soils, some leaf litter degrading fungi of this family, such as L. nuda, have developed the ability to use soil nitrogen fixing bacteria as an important nutrient source (Hutchinson & Barron, 1997). In this way, L. nuda is one of the fungi processing nitrogenous substances in forest soils, such as urea or ammonia (Sagara, 1975). On the other hand, Ossicaulis lignatilis, a member of the Lyophyllaceae within the Tricholomatoid clade, was reported to produce brown-rot wood decay (Redhead & Ginns, 1985).

Agar-plate assays for ligninolytic enzymatic activities of litter decomposing fungi, showed the ability of L. nuda to oxidize ABTS in absence of hydrogen peroxide, suggesting production of phenol oxidases (probably laccases) (Steefen et al., 2000). Furthermore, L. nuda was reported to remove more than 40% of the pyrene (a polycyclic aromatic hydrocarbon) concentration from liquid Mn(II) supplemented cultures suggesting MnP activity (Steefen et al., 2002). Quantitative assays on ligninolytic activity in a number of the so called “ammonia fungi” demonstrate that laccase was the major phenol oxidase enzyme produced by some leaf litter degrading species such as L. nuda (Soponsathien, 1998). Recently, laccase and MnP activities have been quantified in both liquid and solid-state fermentation cultures of this fungus (Pinto et al. 2012).

Leaf litter decay lifestyle is widely distributed among Agaricales whose members play an important role in the carbon cycle degrading lignocellulose in forest ecosystems. L. nuda is the only Tricholomataceae species selected for genome sequencing at the JGI CSP15-1609 on "Wood and leaf litter degrading Agaricales". The genome analysis of L. nuda will permit to compare its lignocellulolytic machinery with those of other leaf litter decaying fungi growing in forests, such as Rhodocollybia butyracea (Omphalotaceae) (also sequenced in this project) or Macrolepiota fuliginosa (Agaricaceae) (accessible at JGI). In addition, it will also improve our knowledge of the mechanisms involved in lignocellulose degradation and the diversity of lignocellulose degrading enzymes.

References

Hutchison, L. J. and Barron, G.L. 1997. Parasitism of algae by lignicolous Basidiomycota and other fungi. Canad. J. Bot., 75: 1006-1011.

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.

Pinto, P.A., Dias, A.A., Fraga, I., Marques, M., Rodrigues, M.A.M., Colaco, J., Sampaio, A., Bezerra, R.M.F. 2012. Influence of ligninolytic enzymes on straw saccharification during fungal pretreatment. Bioresource Technol. 111:261-267.

Redhead, S.A. and Ginns, J.H. 1985. A reappraisal of agaric genera associated with brown roots of wood. Trans. Br. Mycol. Soc. Jap. 26: 349-381.

Sagara, N. 1975. Ammonia fungi- A chemoecological grouping of terrestrial fungi. Contrib. Biol. Lab. Kyoto Univ., 24, 205-276.

Saponsathien, S. 1998. Some characteristics of ammonia fungi 1. In relation to their ligninolytic enzyme activities. J. Gen. Appl. Microbiol. 44, 337-345.

Steffen, K.T., Hofrichter, M. and Hatakka, A. 2000. Mineralization of 14C-labelled synthetic lignin and ligninolytic enzyme activities of litter-decomposing basidiomycetous fungi. Appl. Microbiol. Biotechnol. 54: 819-825.