## 5 Conclusions  
In this study, the degradation of birch, alder and pine sawdust by the WRF _Crucibulum laee_ (Agaricales, _Nidulariaceae_), a litter decomposer, was investigated. The fungal molecular mechanism used to degrade different lignocellulosic substrates was investigated using biochemical analyses as well as proteomics, metabolomics and genomics. The fungus showed the highest radial growth rate on media containing starch and pectin. Fungal exoproteome analysis showed that lacases, lytic polysaccharide monooxygenases (LPMOs), GMC oxidoreductase (AA3_2 and AA7 CAzyme families), as well as expansin-like proteins and lectins were the major secreted proteins in all the media. Metabolomic analysis revealed that, in particular, monosaccharides and carboxylic acids were the major low molecular weight metabolites in the _C. laeee_ culture liquids (CLs) under the experimental conditions. Moreover, the proportion of monosaccharides and polyols in a total pool of identified compounds increased on the sawdust-containing media. Among the polyols, glycerol and erythroid were the predominant compounds on the sawdust-containing media. Metabolic pathway analysis indicates that the fungus can catabolize D-gluconic and D-galacturonic acids and possibly other aldonic acids. This appears to provide _C. laeee_ with certain environmental advantages. For example, rapid oxidation of glucose and other monosaccharides released during the destruction of plant cell wall polysaccharides prevents the use of carbohydrates by other competing microorganisms, which are abundant in forest litter. The results of the study demonstrate the potential of _C. laeee_ to degrade various lignocellulosic substrates and provide a fundamental understanding of the enzymes responsible for the degradation. As this is the first attempt to analyze a profile of secreted extracellular proteins for lignocellulosic biomass degradation in a member of the _Nidulariaceae_ family, it is likely to contribute to better understanding of lignocellulosic biodegradation mechanisms by fungi of this family. A better understanding of the mechanisms of wood biopolymer decay by different types of wood-destroying fungi will allow the identification of new enzymes for the development of more effective preparations and/or technologies for the processing of lignocellulosic waste in the future. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/jof11010021/s1](https://www.mdpi.com/article/10.3390/jof11010021/s1)]([https://www.mdpi.com/article/10.3390/jof11010021/s1](https://www.mdpi.com/article/10.3390/jof11010021/s1)), **Figure S1**. Exoproteome of _Crucibulum leave_ LE-BIN 1700 cultivated on: control glucose-peptone medium (**GP**); GP medium containing sawdust of alder (**GP-A**); GP medium containing sawdust of birch (**GP-B**); GP medium containing sawdust of pine (**GP-P**). For the data on MALDI TOF/TOF MS/MS analysis of the highlighted protein spots, please, refer to Figure 5; Figure S2. Amino acid sequence alignment of TFK41392.1 and TFK41393.1 _Crucibulum leave_ proteins with LPMO-like copper protein X325 family from _Laetisaria arcalis_ (MK088083). Strictly conserved amino acids are shown in red blocks. Residues of the semi-conservative GGDGN loop are framed in black frame; the strictly conserved residues--two histidines and Asp, involved in copper ion coordination in an active center of the enzyme are marked by asterisks; and the strictly four conserved cysteines forming two disulfide bonds are marked by triangles. The Asn residue involved in N-glycosylation is marked by black point; Figure S3. Amino acid sequence alignment of TFK42532.1 and TFK42953.1 _Crucibulum leave_ proteins with fungal loosenins. Alignment includes _Berkandera alusta_ Loos1 (GenBankk code ADI72050.2), _Neurospora crassa_ N2 (GenBankk code XP_959591.1), _Phanerohaete carnosa_ PcaLOOL2 (GenBank code EKM55357.1), _P. carnosa_ LOOL7 (GenBankk code EKM53490.1), _P. carnosa_ LOOL9 (GenBankk code EKM52742.1) and _Pcarnosa_ LOOL12 (GenBankk code EKM51974.1).