Investigation of biochemical and biotechnological potential of a thermo-halo-alkali-tolerant endo-xylanase (GH11) from Humicola brevis var. thermoidea for lignocellulosic valorization of sugarcane biomass

Hemicellulose is an important source of pentose sugars, which are precursors of products of high economic value, such as prebiotic oligomers, sugar alcohols, organic acids, and biofuels. Enzymatic hydrolysis is the most efficient method of converting hemicellulose into sugars, where efficient thermotolerant fungal xylanases hydrolyze the xylan fractions present in the hemicellulose into xylose and xylooligomers. Xylanases are potential candidates for improved enzyme cocktails that increase saccharification yields in synergy with other cellulolytic and hemicellulolytic enzymes complexes. In this context, endo-xylanase from the thermophilic fungus Humicola brevis var. thermoidea (XylHb) was purified, biochemically and biophysically characterized, and its biotechnological potential was evaluated. XylHb exhibited a molecular weight of 26 kDa and biophysical analyzes revealed that XylHb is mainly formed by β sheets, and exhibits maximum exposure of its tryptophan residues at high temperatures. The characterization of the biochemical properties of XylHb indicated greater tolerance to wide pH (5.0–10.0), temperatures (50–70 °C), and NaCl concentrations (0.1–2.0 mol L−1), as well as better kinetic efficiency than the Cellic®HTec2 cocktail for birchwood xylan hydrolysis. Additionally, saccharification tests of pre-hydrothermally treated sugarcane bagasse after 72 h showed that the complementation of Cellic®CTec2 with XylHb (1:1; w/w) caused a significant increase in glucose released (7.52 ± 0.01%) and total reducing sugars (14.07 ± 0.02%) about commercial enzymatic control. Thus, the addition of XylHb to commercial cellulase suggests a potential for diverse industrial applications improving the saccharification of lignocellulosic biomass.