Chemical conversion of <i>Pleurotus ostreatus</i> mycelium into biodegradable films with tailored properties

The urgent need to replace petroleum-derived plastics with renewable, low-impact materials calls for manufacturing strategies that minimize chemical processing and valorize whole biological resources. This study presents a sustainable route for producing biocomposite films directly from the entire mycelial biomass of Pleurotus ostreatus, bypassing the conventional chitin extraction, which typically relies on harsh chemicals and generates significant waste. Although fungal mycelium is widely recognized as a source of chitin, the use of the whole fungal biomass for film production has been explored only to a limited extent. Here, we demonstrate that a mild alkaline treatment can convert intact mycelial biomass into cohesive, functional films without isolating chitin or removing other biomass components. We systematically examined how alkaline incubation time and plasticizer content govern film morphology, physicochemical and mechanical properties, water vapor permeability, and biodegradability. Among the tested formulations, films treated for 24 h and containing 25 wt % plasticizer exhibited a tensile strength of 10.8 MPa and an elongation at break of 13.1%, while maintaining a moderate water vapor permeability of 10.4 μg/day·m·Pa. This ″whole biomass″ approach offers significant advantages in process simplification, resource efficiency, and cost reduction. Our findings position unrefined fungal biomass as a versatile and scalable platform for the green manufacturing of biobased films, expanding the current landscape of biobased materials aligned with circular-economy principles and offering broad application potential.