Bio-based Strategies to Enhance the Performance of Trametes versicolor Mycelium-Based Leather-Like Materials

Mycelium-based materials are emerging as promising bio-derived alternatives to animal and synthetic leather. However, their practical implementation is limited by insufficient mechanical strength and high surface hydrophilicity, which compromise dimensional stability and durability under humid conditions. This study investigates post-processing strategies aimed at enhancing structural integrity and improving surface hydrophobicity – an essential parameter to increase water resistance and extend service life – of Trametes versicolor mats produced through liquid-state surface fermentation (LSSF). A preliminary assessment showed that hot pressing increased the ultimate stress of glycerol-treated sheets from 0.31 ± 0.06 to 0.45 ± 0.06 MPa, confirming its suitability as a standard consolidation step. Subsequently, sorbitol- and citric acid-treated mats were coated with seven bio -based formulations, including proteins, polysaccharides, shellac, and wax–oil blends, and evaluated through static water contact angle (WCA) measurements. The uncoated mat exhibited the highest hydrophobicity (99.8 ± 15.0)°, while coated samples showed WCAs ranging from 65.1° (corn zein) to 95.3° (wax–oil balm). Coatings rich in hydrophobic long-chain molecules yielded the best water repellence, whereas protein- and polysaccharide-based films primarily altered surface texture without enhancing wettability. These results highlight the importance of formulation chemistry – particularly plasticizer content – in determining surface hydrophobicity, and provide a foundation for the development of scalable, fully bio-based surface finishing treatments for fungal leather-like materials.