White rot fungusInonotus obliquuspretreatment to improvetran-1,4-polyisoprene extraction and enzymatic saccharification ofEucommia ulmoidesleaves

摘要

This study proposes an innovative strategy of lignocellulose biodegradation byInonotus obliquusunder solid-state fermentation in extractingEucommia ulmoidestrans-1,4-polyisoprene (EUG) and producing reducing sugars efficiently. EUG and sugars were obtained through the white rot fungal pretreatment ofE. ulmoidesleaves, ultrasound-assisted solvent extraction, and enzymatic saccharification. After mere 2-day fermentation, the loss of lignin, cellulose, and hemicelluloses of the leaves achieved 7.11%, 3.47%, and 6.44%, respectively due to the high activity levels of manganese peroxidase (MnP, 973 IU g(-1)) and lignin peroxidase (LiP, 1341 IU g(-1)) produced by the fungus. The breakdown of fibrous networks brought higher yields of EUG and reducing sugars. The highest extraction yield of EUG was 4.86% from the 2-day fermented leaves, 31.4% greater than that from the control (3.69%). Meanwhile, the leaf residues after EUG extraction released 97.8 mg g(-1)reducing sugars with enzymatic saccharification, 77.5% greater than that from the control (55.1 mg g(-1)). The results demonstrated thatI. obliquuscould useE. ulmoidesleaves as substrate to produce high-activity-level ligninolytic enzymes in a very short time and the lignocellulose selective degradation ofE. ulmoidesleaves enhanced the yields of EUG and reducing sugars.