Peroxidases from Phanerochaete chrysosporium not only directly function on cellulosic substrates but also boost cellulase activity

Cellulose and hemicellulose are the structural components of cell wall in plants and the most abundant carbon source in nature. Since the biorefinery using lignocellulosic biomass as feedstock has been in spotlight as one of the alternatives for petroleum-based chemical industry, not only lignin degradation but also the enzymatic saccharification of cellulosic substrate to fermentable sugars (e.g. glucose) is the most important topic for developing the efficient biorefinery system. Herein, we report that lignin-degrading biocatalysts are likely associated with saccharification by demonstrating that lignin peroxidase (LiP) and manganese peroxidase (MnP) from Phanerochaete chrysosporium directly hydrolyze various (hemi)cellulosic substrates even including insoluble and crystalline cellulose such as carboxymethyl cellulose (CMC), p-nitrophenyl cellobiose (pNPC), cellobiose, xylan, regenerated amorphous cellulose (RAC), and Avicel^®. Both LiP and MnP simultaneously exhibited endo-, exo-acting, and β-glucosidase activities that are essential for obtaining the fermentable sugar from lignocellulose. The optimum conditions and the specific activities were also determined for the various substrates. In addition to the direct hydrolysis of cellulosic substrate, both LiP and MnP boosted cellulase activity. The boosting effect was evaluated by degree of synergism (DS) and the highest DS was achieved up to 1.87 when using 1 unit cellulase and MnP cooperatively for 10 gL^-1 of Avicel^®. The result discussed here would be a promising insight for the simultaneous process including lignin-degradation and the saccharification in the biorefinery.