Evaluation of vat blue removal by Aspergillus niger using scanning electron microscopy and glucose oxidase enzyme activity

Abstract

The use of fungi to reduce dye removal in water from diverse industries can be an efficient option for solving environmental problems. However, the mycoremediation processes involved in color removal are unknown. In this article, Aspergillus niger CDBB-H-175 was applied for vat blue discoloration (DC). Hence, inactive biomass by two methods (metabolic inhibitor and heat) and active biomass were studied by scanning electron microscopy and enzyme activities to determine the vat blue DC. When using active biomass, 62% of DC, glucose oxidase (GOX) enzyme activity, 1.19 U/mL and 1.43 mg/L of H₂O₂ were obtained. It was observed that 68% of DC was due to the degradation process and 32% was due to biomass sorption. When the biomass was inactivated with sodium azide, DC increased by 90% (1.45-fold), low GOX activity (0.138 U/mL), and H₂O₂ (0.25 mg/L) were detected. High DC might be due to a high dye sorption in hyphae, since an increase in the thickness and morphology of the hyphae were observed by SEM. Inactivated biomass through heating, showed a 69.5% of DC, where 0.01 U/mL GOX and 0.25 mg/L H₂O₂ were reached, demonstrating that inactivation of A. niger biomass by sodium azide can be considered as an alternative treatment for colored wastewater.