Hybrid Biomass From Co-Culturing Filamentous Fungi on Food Waste for Alternative Leather Material Production

Co-culturing fungi offers a promising strategy for generating hybrid fungal biomass with structural and functional properties for developing fungal-based alternative leather. In this study, two filamentous fungi, Aspergillus oryzae and Rhizopus delemar, were co-cultured to valorise food waste through production of fungal materials with enhanced mechanical properties owing to chitin-rich biomass of A. oryzae and chitin-chitosan-rich biomass of R. delemar. After confirming symbiotic growth on solid media and in submerged semi-synthetic media, the system was applied to a complex medium prepared from bread and lemon waste. Cultivation was scaled up to a 4.5 L bubble-column bioreactor. The harvested biomass was tanned with chestnut tannin and processed into materials using wet-laid method. Symbiotic growth was verified by polymerase chain reaction (PCR) amplification and visually via optical and scanning electron microscopy (SEM). Unlike the pelletised morphology typical of A. oryzae, the co-culture produced dispersed mycelium favouring material formation. Co-cultures yielded higher ethanol concentrations (12-14 g/L), with biomass yields exceeding those of R. delemar (~0.2 g/g) and comparable to A. oryzae (~0.3 g/g) monocultures. The highest tensile strength and elongation achieved were 11.7 MPa and 8% respectively. Overall, this work establishes fungal-fungal co-culture as a transformative approach for producing hybrid biomass for fungal-based leather alternatives.