Production of Aspergillus niger cellulase using defatted rice bran and its use in lignocellulosic saccharification reaction

One of the primary constraints on the utilization of lignocellulosic resources is the cost of cellulase. Therefore, the objective of this experiment was to prepare cellulase from low-cost cellulose substrates and to utilize lignocellulose through enzymatic means. Defatted rice bran, a byproduct of rice processing, is a plentiful and cost-effective raw material that can be employed as a substrate for the production of cellulase through solid-state fermentation (SSF). To enhance the efficacy of cellulase, the impact of fermentation mode on cellulase production by Aspergillus niger DM（A. niger DM） utilizing defatted rice bran was examined. The findings revealed that the cellulase activity generated through SSF was markedly superior to that of SmF. The results showed that cellulase was produced by SSF at 36℃ with 75 % defatted rice bran pretreated with NaOH as substrate. On day 4, the filter paper enzyme activity (FPase), carboxymethyl cellulase activity (CMCase) and β-glucosidase activity were 27.23 ± 2.76U/g, 146.44 ± 1.22U/g and 97.51 ± 4.53U/g, respectively. Additionally, the enzymatic properties of this cellulase were characterized by an optimal pH and temperature of 6.0 and 50℃, respectively, and good stability. The hydrolysis of a variety of cellulosic biomass using the crude enzyme solution yielded a reducing sugar concentration of up to 30 g/L–47 g/L after 72 hours. After comparing with commercial cellulases, it was found that the enzymatic hydrolysis performance of A. niger DM cellulase in this study was comparable to commercial cellulases, and could replace commercial cellulases. •The activity of cellulase produced by SSF was significantly higher than that by Smf.•The crude enzyme produced has high enzyme activity and good stability.•The cellulose crude enzyme produced has a better enzymatic hydrolysis effect on defatted rice bran.•Defatted rice bran could be an ideal raw material for cellulase production.