Simultaneous production of Aspergillus niger biomass and amylolytic enzymes under submerged fermentation using agro-industrial by-products
Several bioproducts can be obtained from the cultivations of filamentous fungi, which makes viable the utilization of fungi for food, pharmaceutical and environmental applications. Besides, filamentous fungi are capable of grown using agro-industrial wastes and by-products as substrate, improving the circular economy and valorization of these residues. In this context, we aimed to produce simultaneously fungal biomass and amylolytic enzymes under submerged fermentation (SmF) using agro-industrial by-products as substrate (wheat bran and potato peel). Aspergillus niger DAOM was the strain used in this study. Factorial designs were performed to achieve higher production of fungal biomass (evaluated by biomass concentration) and amylases (evaluated by amylolytic activity) under SmF performed in two steps. A fractional factorial design (FFD 25-1 with central points) and two full factorial designs (Design 2 and Design 3) were applied in Step 1 and Step 2, respectively. The significance levels and estimated effects were analyzed at a confidence level of 90% and 95% for Step 1 and 2, respectively. It was possible to verify the best conditions to produce fungal biomass and amylolytic enzymes under SmF using wheat bran and potato peel. Wheat bran showed better results for both biomass concentration and amylolytic activity when compared to potato peel (Step 1). In the Step 2, the highest fungal biomass production occurred in two days for both substrates. Biomass concentration was higher in a medium composed by wheat bran (Step 2). Finally, it was possible to determinate that the best conditions to produce fungal biomass are 1% of NaNO3 and pH 7 for wheat bran, while for potato peel + wheat bran are 1% of NaNO3 and pH 5 (Step 2).
Keywords: Amylases, Aspergillus niger, Potato peel, Wheat bran.