Screening, Characterization and Comparison of Endoglucanases/Xylanases from Thermophilic Fungi: A Xylanase with High Activity-Stability Properties.

Thermostable cellulases and xylanases have broad acceptance in food, feed, paper and pulp, and bioconversion of lignocellulosics. Thermophilic fungi serve as an excellent source of thermostable enzymes. This study characterized four endo-β-1,4-glucanases (two glycoside hydrolase (GH) family 5 and two GH7 members) and four endo-β-1,4-xylanases (two GH10 and two GH11 members) from thermophilic fungus , along with one GH10 endo-β-1,4-xylanase each from thermophilic fungus and mesophilic fungus . Comparative analysis was conducted against three previously reported GH10 endoxylanases: two thermostable enzymes from the thermophilic fungus and thermophilic bacterium , and one mesophilic enzyme from model fungus . The GH10 xylanase TtXyn10C (Thite_2118148; UniProt G2R8T7) from demonstrated high thermostability and activity, with an optimal temperature of 80-85 °C. It retained over 60% of its activity after 2 h at 70 °C, maintained approximately 30% activity after 15 min at 80 °C, and showed nearly complete stability following 1 min of exposure to 95 °C. TtXyn10C exhibited specific activity toward beechwood xylan (1130 ± 15 U/mg) that exceeded xylanases from and while being comparable to xylanase activity. Furthermore, TtXyn10C maintained stability across a pH range of 3-9 and resisted trypsin digestion, indicating its broad applicability. The study expands understanding of enzymes from thermophilic fungi. The discovery of the TtXyn10C offers a new model for investigating the high activity-stability trade-off and structure-activity relationships critical for industrial enzymes.