Laccase and lignin peroxidase production by Cerrena unicolor and Loweporus lividus in solid-state fermentation using agricultural biomass as substrate and its application in dye degradation

Lignocellulosic residues (guava leaves, cabbage leaves, pineapple peels, pomegranate peels, orange peels, banana pseudostem, and wheat bran) were used for the production of laccase (LaC) and lignin peroxidase (LiP) via solid-state fermentation (SSF) by fungi (Cerrena unicolor and Loweporus lividus). The results revealed that banana pseudostems presented higher LaC and LiP activities (49.8±1.4 U/g and 7.8±0.24 U/g, respectively) than other agricultural residues did. Banana pseudostems presented increased amounts of lignin (21±0.28%), cellulose (42.8±0.92%), and hemicelluloses (22.3±0.14%), which stimulated enzyme production. The data revealed that glucose (a carbon source), ammonium sulfate (a nitrogen source), an inducer (polysorbate 80, 0.15%), a pH of 4.5, and a 60% moisture content were optimal for LaC and LiP production. Two-level full factorial designs revealed that the variables moisture, pH, polysorbate 80, and glucose significantly influenced LaC and LiP production (p<0.001). A central composite design was applied to optimize the medium components, and glucose and polysorbate 80 influenced LaC and LiP production. The optimized medium (4.82 pH, 0.13% polysorbate 80, and 0.57% glucose) improved LaC (151.9 U/g) and LiP (19.2 U/g) production. The crude enzyme was used to decolorize the dyes. The degradation rates of acid yellow, bromo-chloroform purple, and reactive black 5 were >82%.