Molecular Mechanism And Related Enzyme Characteristics Of White Birch Lignocellulose Degradation By Fomes Fomentarius

White rot basidiomycetes play an important ecological role in lignocellulose recycling and are notable for their rapid degradation of wood polymers via oxidative and hydrolytic mechanisms. Lignocellulose degradation by white rot fungi, such as Fomes fomentarius (L.) Fr., is poorly understood relative to the phylogenesis-related white rot basidiomycete, Phanerochaete chrysosporium. To elucidate the number, structure, expression and regulation of genes involved in the lignocellulosic degradation of the cell wall, proteome and transcriptome analyses were performed on the wood decay fungi cultured for10days in the media containing either of the birch wood powder or glucose as the sole carbon source.1. To study the molecular mechanism of the lignocellulose degradation of the birch wood, a transcriptome analysis of F. fomentarius by using the Solexa method. In total,28695ungienes were screened out. Among them,21255ungienes showed significant (>1E5) sequence similarity with proteins in the NR-database. Gene Ontology (GO) classification indicated that12445ungienes were categorized into biological processes,8252ungienes were grouped into cellular components, and9554ungienes were assigned to the molecular function group. Of21347proteins predicted in the transcriptome,530ungienes could encode potential carbohydrate-active enzymes (CAZY). These putative CAZY genes include240glycoside hydrolases (GH),91carbohydrate esterases (CE),77glycosyltransferases (GT), and18polysaccharide lyases (PL). The expression profiles of the genes involved in lignocellulose degradation were validated using two different carbon sources by real time RT-PCR. The results showed that their expression altered significantly between two different carbon sources, suggesting that the gene expression involved in lignocellulose digestion can be induced.2. Using the2-DE analysis, the changes in the protein profiles induced by different carbon sources was investigated. Twenty eight protein spots showed differences in protein expression, with16spots increased and12spots decreased in abundance. These spots were further analyzed using MALDI TOF/TOF and fourteen of them were identified. Some spots corresponded to transferase activity and binding; others were involved in antioxidant activity. The identified proteins covered a wide range of biological process and molecular function, including single-organism metaboic process, biosynthetic process, catabolic process, response to stress, primary metabolic process, cellular metabolic process, organic substance metabolic process, nitrogen compound metabolic process, transferase activity, heterocyclic compound binding, hydrolase activity, small molecule binding, protein binding, organic cyclic compound binding. Twenty five protein spots were identified by matching peptide mass fingerprints of identified proteins with a local database established, based on the transcriptome sequence of F. fomentarius.3. The enzymatic properties and fermentation medium for lignocellulose-degrading enzymes production of F. fomentarius were screened in static cultures. The results indicated that carbon and nitrogen source influence the secretion of the lignocellulose-degrading enzymes. The optimum culture medium contained the wheat bran and peptone as carbon and nitrogen sources for the production of lignocellulolytic enzymes, respectively. The optimum temperature of ligninase and cellulase of F. fomentarius was50℃and55℃, respectively. The optimum pH of laccase(Lac), manganese peroxidase(Mnp), endo-1,4-β-D-glucanase(CMCase) and cellulose1,4-β-cellobiosidase(CBH) was3,4.5,5and4.5, respectively. The activity of the ligninases was affected by the most different ion obviously. In contrast, the activity of the cellulases was affected very little by the most different ion.