Toward Sustainable Enzyme Production From Agro‐Industrial Residues: Optimizing pH and Soyhull Particle Size in Fungal Fermentation

ABSTRACT Carbohydrase enzymes are critical to sustainable detergent formulations, enabling effective cleaning at lower temperatures and reduced resource use. To improve the economic and environmental viability of enzyme production, this study explored soybean hulls—a low‐value agricultural by‐product—as both carbon source and inducer for enzyme synthesis by Aspergillus niger NRRL 322. A major challenge in using complex lignocellulosic substrates is managing the dynamic interplay between fungal growth, enzymatic hydrolysis, and the induction and repression mechanisms that govern enzyme synthesis. Induction requires sustained generation of intermediate oligosaccharides, while rapid sugar accumulation can trigger feedback repression. To address this, we investigated the effects of pH control strategies and soyhull particle size distributions in both shake flasks and stirred‐tank bioreactors. An initial pH of 5.0 and a heterogeneous particle size range supported balanced carbon release and prolonged enzyme production. Dissolved oxygen–guided substrate feeding further enhanced performance at scale. These findings contribute to the development of robust, cost‐effective processes for enzyme production from agricultural residues, with applications in sustainable surfactant and biorefinery industries.