The β-xylosidase from Ceratocystis fimbriata RM35 improves the saccharification of sugarcane bagasse

The phytopathogenic fungus Ceratocystis fimbriata produced an extracellular β-xylosidase when grown in mineral medium with wheat bran as carbon source. The enzyme was purified and characterized. The molecular mass was estimated by SDS-PAGE (161.6 kDa). The enzyme showed maximum activity at pH 3.9 and 65 °C, and it showed to be significantly thermostable at 60 °C, maintaining 70% of its maximum activity after 24 h of incubation at this temperature. The KM and VMAX using ρNρβXyl were 0.326 mM and 0.91 × 10−3 µmol/min, respectively. The β-xylosidase was partially inhibited by 1 mM of aluminum chloride, copper sulfate II, iron sulfate and SDS. The β-xylosidase combined with a xylanase had an additive effect on beechwood xylan hydrolysis, generating xylose as a final product. The supplementation of the enzymatic cocktail Multifect CL® with the β-xylosidase generated a more efficient hydrolysis of alkali-pretreated sugarcane bagasse when compared to the saccharification performed only by the cocktail Multifect CL®, showing an increase of 97.7% and 45.7% in glucose and xylose release, respectively.