Characterization of Plant-Cell-Wall-Degrading Enzymes of Pleurotus ostreatus and Their Potential Industrial Relevance in Agricultural Waste Valorization and Azo Dye Decolourization

Mushrooms are a promising renewable source of plant-polysaccharide-degrading enzymes that could be explored in food, pharmaceutical, textile, paper industries, biofuel production, and as a potential agent for agricultural-waste valorization. Mycelia cultures of three Pleurotus ostreatus demonstrated hydrolysis of polysaccharides of agricultural wastes (rice straw, corn stover, vegetable peel, sal leaves, wheat straw, and sugarcane bagasse). Screened extracellular enzymes: amylase, cellulase, polygalacturonase, and pectin lyase could participate in the degradation process. Characterization of enzymes revealed optimal amylolytic and cellulolytic activity at 50°C, while pectinolytic activity peaked at 60–70°C. All the enzymes were thermostable (100% activity at 70°C for an hour) and pH-stable (could tolerate pH from 4–10) and metal ions (Ca2+, Cu2, Fe3+, Mg2+, Mn2+ and Zn2+ at 100 ppm), and β-mercaptoethanol, EDTA, and SDS (1%) did not hinder their activities. The enzymes’ kinetic parameters (Km and Vmax) also highlighted their catalytic efficiency. P. ostreatus mycelia cultures could decolourize azo-dyes by producing manganese peroxidase and laccase, underscoring their potential for environmental bioremediation.