, 1994). In a previous study, we demonstrated that P. sordida YK-624 produces MnP (Hirai et al., 1994, 1995) and LiP (Sugiura et al., 2003; selleck compound Machii et al., 2004; Hirai et al., 2005) as ligninolytic enzymes. Recently, gene transformation systems for several species of white-rot fungi have been developed for the overproduction of ligninolytic enzymes and facilitating structure–function studies of these enzymes by site-directed mutagenesis (Mayfield et al., 1994;
Tsukamoto et al., 2003; Tsukihara et al., 2006). We previously constructed a gene transformation system for P. sordida YK-624 using the glyceraldehyde-3-phosphate dehydrogenase gene (gpd) promoter for the heterologous
expression of enhanced green fluorescent protein (EGFP) (Yamagishi et al., 2007) and the homologous expression of recombinant LiP (Sugiura et al., 2009); notably, the ligninolytic activity and selectivity of the transformant expressing LiP were markedly higher than those of wild type (Sugiura et al., 2010). However, Antidiabetic Compound Library ic50 explorations of more effective expression promoters and investigations of proteins involved in lignin degradation are essential to breedings of superior lignin-degrading fungi. In this study, we attempted to isolate the promoter region of a protein that is highly expressed by P. sordida YK-624 under wood-rotting conditions for the overproduction of ligninolytic enzymes using this promoter in woody biomass cultivation. Moreover, the ligninolytic properties of a transformant that overproduces MnP under wood-rotting conditions were examined in detail. Phanerochaete sordida YK-624 (ATCC 90872), uracil auxotrophic strain UV-64 (Yamagishi et al., 2007), recombinant YK-LiP2-overexpression DOK2 transformant A-11 (Sugiura et al., 2009), and P. chrysosporium ME-446 (ATCC 34541) were used in this study. A suspension consisting of 1 g ethanol-treated beech wood meal (60–80 mesh) and 2.5 mL distilled water in a 100-mL Erlenmeyer flask was inoculated with P. sordida
YK-624 and then incubated at 30 °C for 10 days. Proteins were extracted from four fungal-inoculated wood meal suspensions by adding 100 mL extraction buffer (50 mM sodium phosphate, 0.5 mM phenylmethylsulfonyl fluoride, and 0.05% Tween 80) and stirring for 2 h at 4 °C. Soluble proteins were separated by filtering the suspension through a 0.2-μm membrane filter (Advantec). For the removal of phenolic compounds, 1 g acid-treated polyvinyl polypyrrolidone (Charmont et al., 2005) was added to the solution over a 2-h period with constant stirring at 4 °C, and residue was removed by filtering. Proteins precipitated between 30% and 80% saturation of ammonium sulfate were obtained by centrifugation of the solution at 15 000 g for 30 min at 4 °C.