Valorization of Fungal Biomass: A Circular Approach for the Integrated Recovery of Chitosan and Lignocellulolytic Enzymes

Abstract

In this study, an integrated biorefinery approach was used to sequentially recover industrially important enzymes like cellulase, laccase, and lignin peroxidase (LiP), followed by the recovery of chitosan from the residual biomass. The biomass of mushroom fungus (Pleurotus Sajor caju) was first processed to obtain aqueous crude enzyme extracts, which were precipitated using ammonium sulphate and purified by chromatography. Enzyme activities were measured using standard spectrophotometric methods, and protein content was estimated by the Bradford method. After recovering the enzymes, the remaining biomass was utilized for chitin extraction, followed by its conversion to chitosan through demineralization, deproteinization, and deacetylation. The resulting chitosan was characterized by using Fourier transform infrared spectroscopy and X-ray diffraction to evaluate its structural and physicochemical properties, including degree of deacetylation, molecular characteristics, and viscosity.  The results indicate that this integrated method efficiently recovers enzymes and produces good-quality chitosan from the same biomass, making it a promising strategy for sustainable use of biomass and circular bioeconomy practices.