Biodegradation of Cassava Flour Production Wastes in the Brazilian Industry for Industrial Glycohydrolase Enzymes Production by Aspergillus niger

Abstract

Abstract The production of the enzymes α-amylase, glucoamylase, and xylanase by Aspergillus niger DR02 was studied using waste from the Brazilian cassava flour industry. Cassava wastewater (manipueira) at 30% (v/v) was used, either supplemented (M30F10) or not (M30) with 10 g/L of cassava peel flour as a carbon source. Variables such as chemical oxygen demand (COD), proteins, reducing sugars, glucose, nitrate, ammonia, and enzymatic activities were monitored. The results for M30F10 and M30 at 30°C and pH 5.00 showed similar COD removals of 82.88%±12.00 and 82.41%±7.00, respectively. Despite the significant reduction in organic load, the final effluent still requires post-treatment before being discharged into the receiving water body. The addition of cassava peel flour favored the maximum production of 18.40 U/mL±0.15 α-amylase in 72 hours of cultivation, 14.80 U/mL±0.91 xylanase in 96 hours, and 4.50 U/mL±0.29 pectinase in 24 hours. Without medium supplementation, the highest glucoamylase activity (19.90 U/mL±1.01) was obtained in 96 hours. The kinetic adjustment to a first-order model (R²: 0.9998) confirmed the highest efficiency for α-amylase production when the medium was supplemented with peel flour (M30F10), with a production rate of 7.07 x 10⁻² h⁻¹, while the highest glucoamylase production rate was obtained in M30 (3.251 x 10⁻² h⁻¹; R²: 0.9975). These results confirm the effects of mitigating environmental impact and the commercial value enhancement of cassava flour industry waste through biodegradation with the studied strain.

Keywords

• Aspergillus niger
• manipueira
• enzymatic activity
• cassava flour