Engineering Biohybrid Mycelium Fibers through Hierarchical Structuring and Biomineralization

ABSTRACT Engineered living materials (ELMs) that utilize fungal cells have emerged as a class of functional materials, owing to their ability to self‐assemble, adapt, and regenerate. Filamentous fungi growth promotes the formation of a network of interwoven threads, or mycelia, that is of rising interest as a sustainable and versatile material; however, broader application is constrained by comparatively lower strength than synthetic or natural materials. In order to develop mechanical strength, strategies from nature, such as structural hierarchy and mineralization, are leveraged in the material design. In this study, a bioink composed of alginate and a modified strain of the filamentous fungus Aspergillus niger capable of silica mineralization is extruded to create fibers of interconnected mycelium. After fiber incubation, fungal cells exhibit radial hyphal growth extending from the core fiber, which can be tuned by capillary force alignment. Mineralization demonstrates approximately double the stiffness and strength of dried mycelium fibers. Further, twisted and braided fibers exhibit a two‐ to three‐fold increase in elongation at break compared to single fibers. The results show that mycelium morphology and mechanical properties can be tuned through mineralization, growth conditions, and processing.