Enzymatic Potential of a Newly Isolated Aspergillus sp. FSDE16 for Cellulase and Xylanase Production

Abstract

This study characterizes the newly isolated Aspergillus sp. FSDE16 from sugarcane soil, demonstrating its balanced cellulolytic and xylanolytic enzymatic profile, high β-glucosidase production, thermostability, and multiple hydrolytic isoforms under solid-state fermentation conditions. Enzyme production was carried out by solid-state fermentation (SSF) using wheat bran as a low-cost agro-industrial substrate, with 50% initial moisture content, 10 6 spores/g, and incubation at 37 °C. Under these conditions, the maximum activities of CMCase (carboxymethylcellulase) (10.91 U/g) and xylanase (103.2 U/g) were reached after 120 h, while β-glucosidase peaked at 94.11 U/g after 144 h. To evaluate the effects of different variables on enzyme production, Response Surface Methodology (RSM) was applied. The experimental conditions resulted in increased enzyme yields (14.36 U/g CMCase, 68.74 U/g β-glucosidase, 212.40 U/g xylanase), establishing optimal parameters at 32 °C with tailored moisture and inoculum levels. The crude enzymatic extract exhibited optimal activity at 60 °C for CMCase and xylanase and at 70 °C for β-glucosidase. CMCase and β-glucosidase showed maximum activity under acidic conditions (pH 4.0 and 5.0), whereas xylanase performed best at pH 6.0–7.0. Thermostability assays demonstrated good enzyme stability, particularly between 50 and 60 °C. Zymogram analysis revealed multiple cellulase and xylanase isoforms. These results identify Aspergillus sp. FSDE16 as a promising local isolate with a balanced lignocellulolytic enzyme profile, supporting its potential for future applications in lignocellulosic biomass valorization and the circular bioeconomy.