Characterization of agro-wastes as substrate for microbial laccase production

Abstract

Laccase, a widely utilised blue copper oxidoreductase enzyme, catalyses the oxidation of various substrates, including phenolic compounds, while reducing molecular oxygen to water. This study aimed to evaluate the potential of agro-wastes, namely corncob, sugarcane bagasse, and plantain peduncle, as substrates for laccase production, emphasising the effects of alkaline pretreatment using NaOH. Analytical methods, including scanning electron microscopy (SEM), Energy Dispersive X ray (EDX), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR), were employed to analyse the structural and chemical changes induced in these materials. The SEM-EDX results revealed alterations in elemental composition, showcasing reduced lignin-associated elements and improved exposure of cellulose. The XRD analysis demonstrated an enhanced crystallinity index, indicating the selective removal of amorphous components (lignin and hemicellulose), thus increasing cellulose accessibility. The FTIR analysis identified significant changes in functional groups, such as the disappearance of lignin-related peaks and the amplification of cellulose and hydroxyl signals. These findings established that NaOH pretreatment effectively modifies the physicochemical properties of agro-wastes, rendering them cost-efficient substrates for laccase production.