MULTI-ENZYME PRODUCTION BY ASPERGILLUS NIGER ISOLATED FROM CORN COB

Lignocellulosic agricultural wastes such as corn cobs are generated abundantly but poorly managed, causing environment al pollution. Corn cobs are rich in cellulose, hemicellulose, lignin, and residual starch, making them suitable substrates for fungal growth and enzyme production. This study aimed to identify a fungus from corn cob waste and to evaluate its capacity to produce laccase, amylase, and cellulase using corn cob as a low-cost substrate for potential biotechnological applications. Submerged fermentation was carried out in a mineral salt medium supplemented with corn cob over a 6-day incubation period. Fungal biomass was monitored gravimetrically, while enzyme activities were determined using standard spectrophotometric assays: DNS - 3,5-Dinitrosalicylic Acid method for amylase and cellulase, ABTS – 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid oxidation for laccase activity, and the Bradford method for protein concentration. The fungus was morphologically identified as Aspergillus niger, and the results showed a steady increase in fungal biomass and enzyme production with incubation time, followed by a decline at later stages. Optimum amylase activity (68.98 mmol/min) was recorded on day 3, cellulase activity peaked at about 120 mmol/min on day 4, and maximum laccase activity (0.85 mmol/min) was observed on day 4. Protein concentration and fungal biomass increased progressively, reaching a maximum of about 0.95 mg/mL and 0.085 g, respectively, on day 5. Overall, enzyme production correlated with fungal growth, confirming efficient utilization of corn cob as a substrate. The Aspergillus niger isolated from corn cob possesses strong lignocellulolytic potential, with cellulase being the most prominently produced enzyme, followed by amylase and laccase. Future research should focus on optimizing fermentation conditions, substrate pretreatment, and large-scale production to enhance enzyme yield and industrial use .