Multi‐enzymatic recovery of fungal cellulases (Aspergillus niger) through solid‐state fermentation of sugarcane bagasse

Abstract

AbstractIn this study, the optimum conditions for the multi‐enzymatic recovery of cellulases produced by Aspergillus niger were investigated using sugarcane bagasse. Two extraction methods were investigated: the two‐stage solid–liquid extraction (SLE) followed by ultrasound‐assisted extraction (UAE), and the single‐stage SLE. The ultrasound effects were evaluated using a Doehlert design, in which the pH (5.0–9.0) and sonication power (0.8–2.0 W ml−1) were independent variables. For the single‐stage SLE, temperature (25–45°C), time (10–60 min), and pH (5.0–9.0) were analyzed using the Box–Behnken design. Both processes were monitored to evaluate FPase, CMCase, and β‐glucosidase (U ml−1) activities. The maximum enzymatic activities (EA) obtained for FPase, CMCase, and β‐glucosidase in the SLE–UAE were 0.352, 0.321, and 1.412 U ml−1, respectively. Unlike in most previous studies, sonication was insignificant (p < 0.05) with respect to the enzymatic complex within the evaluated ranges. Moreover, sonication changed the EA when lower than 1.2 and higher than 1.6 W ml−1, mainly inhibiting the EA of β‐glucosidase. The single‐stage SLE was more effective than the two‐stage SLE–UAE, and the maximum EA values for FPase, CMCase, and β‐glucosidase were 0.354, 0.303, and 3.135 U ml−1, respectively. The single‐stage process was better because it consumed less energy, required simpler equipment, and provided higher efficiency in a shorter time. This study will improve diversified enzyme extraction from sugarcane bagasse, reduce enzyme production costs, and enhance bagasse utilization.