Bovine serum protein standard solution

Waste wheat straw (WWS) was supplied by the Shandong Quanlin Group (Shandong, China). The large amount (69.2%) of ash contained in the WWS was washed out using tap water at 1:10 (w/v) for five times, and stored at 4 °C [6 (link)]. Commercial cellulase (Cellic® CTec.2.0) was provided from Novozymes North America (Franklinton, NC). Humic acid was purchased from Sigma-Aldrich (Shanghai, China), and metallic salts (KCl, NaCl, CaCl₂, FeCl₂·4H₂O, FeCl₃·6H₂O, AlCl₃) was analytical grade and purchased from Nanjing Reagent Company (Nanjing, China). Bradford reagent and bovine serum protein standard solution were also purchased from Sigma-Aldrich (Shanghai, China).

The branches and twigs of PM were harvested from the planting at the Guangzhou Academy of Forestry. After air-drying for 24 h, the branches and twigs were ground and sieved through a 40-mesh sieve. The resultant PM sawdust was stored at room temperature until processing. The crude endo-β-1–4-xylanase used in this study was produced from Trichoderma reesei and provided by Jiangsu Kangwei Biotechnology Co., Ltd. of China. The measured enzyme activity was 30 U/mL. Commercial cellulase (Cellic® CTec.2.0) was provided by Novozymes North America (Franklinton, NC). Bradford reagent and bovine serum protein standard solution were purchased from Sigma–Aldrich (Shanghai, China). Other chemicals, such as H₂SO₄, MgSO₄, CaCl₂, KH₂PO₄ and (NH₄)₂SO₄, were of analytical grade and were purchased from Nanjing Reagent Company (Nanjing, China).