Sustainable use of soybean meal in laccase production by Pleurotus ostreatus: Optimization of production and characterization of the enzyme

Abstract

Laccases are oxidoreductive enzymes found in animals, plants, and fungi. Due to their ability to catalyze the oxidation of different phenols and aromatic amines. These enzymes have been widely applied in several sectors, including pollutant degradation, cosmetics, food, and bioenergy industries, especially laccases of fungal origin. In this context, solid-state fermentation (SSF) emerges as a sustainable, economical, efficient, and environmentally friendly alternative for producing this enzyme, utilizing agro-industrial waste. This study aimed to produce, optimize, and characterize laccase by Pleurotus ostreatus cultivated in SSF using soybean meal. Enzyme production was monitored over 240 h to determine the optimal time, followed by a Central Composite Rotational Design (CCRD) to evaluate the parameters of moisture, pH, glucose, and copper sulfate. The characterization of the enzyme included optimal pH and temperature, determination of kinetic constants (K_m and V_max), molecular weight, and zymography. In optimizing enzyme production, pH and humidity were significant factors; the optimal condition was at pH 6.8 and 61.4 % humidity, resulting in an enzymatic activity of 12.85 U/mL and a recovery rate of 82.16 %. In the characterization, the laccase showed maximum activity at neutral pH and 30 °C (23.15 U/mL), with an estimated molecular weight of 65.0 kDa. The results indicate that the enzyme produced is viable for application in industrial and biotechnological processes. Furthermore, soybean meal proved to be a viable, sustainable, and cost-effective alternative for producing laccase by P. ostreatus.