Utilization of potato peels waste for production, purification, and characterization of cold-adapted amylase under solid state fermentation by Penicillium goetzii AUMC 498

This study explores the utilization of potato peel waste as a substrate for producing cold-adapted amylase under solid-state fermentation (SSF) using Penicillium goetzii AUMC 498. Optimization through Box-Behnken design identified pH, incubation period, and beef extract concentration as key factors, achieving a maximum activity of 4.21 U/g dry substrate at pH 7 and 10 °C after 6 days. The enzyme was purified via two-column chromatography (Trilite MA12 and Sephacryl S 200), resulting in a 63.6-fold increase in purity and a molecular weight of 51.91 kDa confirmed by SDS-PAGE. The purified amylase exhibited optimal activity at pH 5 and 25 °C, with sorghum starch as the preferred substrate (594.68 U/mg). Activity was significantly enhanced by MnSO₄ and ZnSO₄, while NiCl₂, SDS, and EDTA inhibited it. Kinetic constants for pure amylase were determined for six types of starch: soluble starch, sorghum starch, oat starch, maize starch, wheat starch, and rice starch. The Km values were 575.75 mM, 59.1 mM, 149.27 mM, 195.9 mM, 81.44 mM, and 37.48 mM, respectively. These findings demonstrate the effective conversion of potato peel waste into a value-added cold-adapted biocatalyst with desirable catalytic and stability characteristics. The ability of the enzyme to function efficiently at low temperatures highlights its strong potential for use in energy-efficient industrial processes, particularly in the food, detergent, textile, and starch-processing industries. Moreover, the utilization of agro-industrial waste as a fermentation substrate provides an environmentally sustainable and economically attractive approach, reinforcing the relevance of this study to waste valorisation strategies and green biotechnological applications.