Xylan

The polysaccharides of sodium alginate, carrageenan, agar, cellulose, chitin, starch, glucan, hemicellulose, xylan and xanthan were purchased from Sangon (Shanghai, China). PolyM and polyG (purity > 97%) were purchased from Qingdao Haizhida Biotech Co., Ltd. (Qingdao, China). Other chemicals and reagents used in this study were of analytical grade.

The filamentous fungus used in this work was the thermophilic fungus Chaetomium thermophilum CGMCC3.17990, provided by Doctor Duochuan Li of Shandong Agricultural University. Glycerol, glucose, cellobiose, MCC, xylose, arabinose, XOS and xylan were purchased from Sangon Biotech Co., Ltd. (Shanghai, China) and used as different carbon sources. Spores of the strain were kept in 80% (v/v) Glycerol at − 20 °C. One percent (w/v) of the different carbon sources was added to minimal medium (MM) as described previously [40 (link)]. All media were sterilized at 115 °C for 30 min. Two hundred microliters of spores (7 × 10⁷/mL) were inoculated into 100 mL of medium and cultured at 50 °C with shaking at 200 rpm for 5 days, and samples were collected every day. Substrates and fungal biomass were removed using eight layers of gauze and centrifuged at 8000 rpm at 4 °C for 15 min. The supernatants were stored at 4 °C and used in further experiments.