Uncovering the Design Rules for Sustainable Growth of Mineralized Mycomaterials

Mycomaterials, materials made from filamentous fungi, have several advantages over traditional materials such as their genetic programmability and self-healing properties. However, their lack of mechanical strength and cost of production often constrain the applications in which they can be used in. In this work, we take inspiration from natural systems to overcome these challenges by elucidating design principles for mineralization-based enhancement of mechanical strength and synthetic lichen-based low-cost growth. We demonstrate that surface display of an enzyme from sea sponges, silicatein α, on the hyphae of the filamentous fungus Aspergillus niger enables mineralization of polysilicate and that this does not impact fungal growth. We also show that this strategy can be extended to other silicatein α variants and characterize how the degree of mineralization can be modulated. We then demonstrate that mineralization enhances the mechanical properties of the mycelium including its tensile strength, modulus, and toughness. Finally, we show how these reinforced mycelia can be grown without external carbon sources using a synthetic lichen-based coculture to facilitate low-cost biomanufacturing. Together, our results lay the groundwork for the sustainable production of mineralized mycomaterials and create a new model system to study how mineralization impacts growth and mechanical properties.