Identification and characterization of genes related to cellulolytic activity in basidiomycetes.

Enzymes produced by basidiomycetes that are involved in the cellulose degradation process, and their respective codifying genes, must be identified to facilitate the development of novel biotechnological strategies and applications in the agro-industry. The objective of this study was to identify prospective cellulase-producing genes and characterize their cellulolytic activity, in order to elucidate the potential biotechnological applications (with respect to vegetal residues) of basidiomycetes. The basidiomycete strains Lentinula edodes U8-1, Lentinus crinitus U9-1, and Schizophyllum commune U6-7 were analyzed in this study. The cellulolytic activities of these fungi were evaluated based on the halo formation in carboxymethyl cellulose culture medium after dyeing with Congo red. The presence of cellulase-codifying genes (cel7A, cel6B, cel3A, and egl) in these fungal strains was also evaluated. L. edodes and S. commune presented the highest cellulolytic halo to mycelial growth radius ratio, followed by L. crinitus. Four genes were amplified in the L. edodes strain, whereas three and one genes were isolated from L. crinitus and S. commune, respectively. The cel6B gene (L. edodes) presented the conserved domain glyco_hydro_6 and characterized as cellobiohydrolase gene. The results of this study contribute to the existing knowledge on cellulases in basidiomycetes, and serve as a basis for future studies on the expression of these genes and the characterization of the catalytic activity of these enzymes. This allows for better utilization of these fungi in degrading vegetal fibers from agro-industrial residues and in other biotechnological applications.

Screening of basidiomycetes in submerged cultivation based on antioxidant activity.

Submerged cultivation of medicinal basidiomycetes is a reproducible and efficient method of producing mycelia and metabolites. The antioxidant activity indicates its medicinal properties and is an important tool for basidiomycete screening. In this study, we analyzed the production of mycelial biomass and exopolysaccharides and the antioxidant activity of basidiomycete strains in submerged cultivation. Twenty-five strains were used for submerged cultivation in extract malt medium, and the production of mycelial biomass and exopolysaccharides was evaluated. Antioxidant activity was determined using the 1,1-diphenyl-2-picrylhydrazyl method. Among the 25 evaluated strains, Lentinus crinitus produced the highest biomass, reaching 1190 ± 52 mg·L(-1)day(-1); Agaricus subrufescens strains had the highest exopolysaccharide production from 18.96 ± 0.15 to 20.97 ± 2.10 mg L(-1)·day(-1). Additionally, A. subrufescens showed the highest total antioxidant activity, reinforcing the therapeutic potential of this basidiomycete. No significant correlation was found between mycelial biomass or exopolysaccharide production and antioxidant activity; however, the results depended on each species and the strains of the same species. We found large variations in the production of mycelial biomass and exopolysaccharides and in antioxidant activity among different species and among strains of the same species. Thus, evaluating the total antioxidant activity is an important tool for identifying strains with biotechnological potential.