A plant biomass–degrading enzyme consortium from Aureobasidium leucospermi LB86 with biotechnological potential

Abstract Cellulolytic and hemicellulolytic enzymes belong to the hydrolase class (EC 3.2) and play a fundamental role in the depolymerization of lignocellulosic biomass, with broad industrial relevance. The growing demand for more efficient and economically viable biotechnological processes has driven the prospecting of new enzyme-producing microorganisms with increased robustness under adverse process conditions. In this study, the production of cellulase, xylanase, β-glucosidase, and β-xylosidase by the yeast Aureobasidium leucospermi LB86 was investigated through solid-state fermentation using wheat bran as the substrate, followed by functional characterization of the fermentative extract. The highest enzymatic activities were observed under slightly acidic pH conditions, ranging from 5.0 to 6.5. Cellulase and xylanase exhibited optimal activity at 50–55 °C, whereas β-glucosidase and β-xylosidase showed maximum activity at 40 °C. The enzymes retained significant activity after thermal incubation within the evaluated temperature ranges. β-glucosidase and β-xylosidase displayed moderate tolerance to glucose, xylose, and arabinose, maintaining residual activities above 60% at concentrations of up to 0.5 M. β-glucosidase activity was not affected by the presence of 10% (v/v) ethanol, either at its optimal pH or at pH 5.0. The enzymatic extract exhibited tolerance to most biomass pretreatment–derived compounds, with the exception of gallic and tannic acids.