Effect of nanomaterials on cellulase enzyme produced by Aspergillus costaricensis and Trichoderma parareesei grown on rice husk.

Rapidly developing sustainability raises concerns about the role of nanoparticles in environmental applications; however, the influence of these nanoparticles on fungal cellulase activity remains unclear. The present research assessed the role of nanoparticles as magnetic iron oxide (Fe₃O₄) and zinc oxide (ZnO) on cellulase activity using two selected fungal species. Two fungal species, Trichoderma parareesei and Aspergillus costaricensis, were studied. A pure fungal culture was cultivated for its cellulase production using rice husk as substrate to check the role of nanoparticles in its hydrolytic efficiency. After 4 days of incubation at a pH of 5 and a temperature of 30 °C, the two pure cultures of fungal species proved to be efficient in cellulase activity on rice husk. The cellulase production of T. parareesei using rice husk as substrate was the highest compared to the control and to A. costaricensis. It appeared that nanoparticles significantly enhanced cellulase activity of the two studied fungal species, which are effective in rice husk degradation. The optimal concentration of Fe₃O₄ nanoparticles was found to be 20 ppm for T. parareesei and 300 ppm for A. costaricensis, while the optimal concentration of ZnO nanoparticles was 2.5 ppm and 7.5 ppm for T. parareesei and A. costaricensis, respectively. At these concentrations, maximum cellulase activity using Fe₃O₄ NPs reached 0.244 FPU/mL for T. parareesei and 0.106 FPU/mL for A. costaricensis, revealing 12-fold and fivefold enhancement compared to the untreated control. Additionally, the treatment with ZnO NPs resulted in higher cellulase productivity, reaching 0.203 FPU/mL and 0.111 FPU/mL for T. parareesei and A. costaricensis, respectively.