Growing sustainable materials from filamentous fungi

The urgent need to transition to a more sustainable way of life is driving the development of natural and sustainable materials. One such example is mycelium materials, which are partially or solely composed of hyphae, the vegetative life form of filamentous fungi. Mycelium materials offer a sustainable and environmentally friendly alternative to synthetic materials like plastics and to animal leather, by minimizing waste, reducing CO2 emissions and promoting a circular economy. In their natural habitat, fungi play a vital role in maintaining balanced forest ecosystems by decomposing and recycling organic matter. From a material application perspective, the mycelium itself is now being considered as a product that can be easily generated by cultivating the fungus on renewable biomass feedstocks. Mycelium-based composites and pure mycelium materials can be produced through different fermentation techniques, including solid-state (SSF), liquid-state submerged (LSF) and liquid-state surface fermentation (LSSF). Interestingly, the properties of mycelium materials are highly tuneable by altering the growth and post-growth process parameters, the choice of fungal species and the used substrate. Although the link between the biology of a living organism and the emergent material characteristics thereof offers great opportunities for fine-tuning material properties, a current lack of understanding of the underlying scientific principles makes industrial scalability and product reproducibility a challenging step. In this article, we discuss the opportunities and challenges of mycelium materials as a novel class of biomaterials.