The current physical goods economy produces materials by extracting finite valuable resources without taking their end of the life and environmental impact into account. Mycelium-based materials offer an alternative fabrication paradigm, based on the growth of materials rather than on extraction. Agricultural residue fibres are inoculated with fungal mycelium, which form an interwoven three-dimensional filamentous network binding the feedstock into a lightweight material. The mycelium-based material is heat-killed after the growing process. In this paper, we investigate the production process, the mechanical, physical and chemical properties of mycelium-based composites made with different types of lignocellulosic reinforcement fibres combined with a white rot fungus, Trametes versicolor. This is the first study reporting the dry density, the Young’s modulus, the compressive stiffness, the stress-strain curves, the thermal conductivity, the water absorption rate and a FTIR analyse of mycelium-based composites by making use of a fully disclosed protocol with T. versicolor and five different type of fibres (hemp, flax, flax waste, softwood, straw) and fibre processings (loose, chopped, dust, pre-compressed and tow). The thermal conductivity and water absorption coefficient of the mycelium composites with flax, hemp, and straw have an overall good insulation behaviour in all the aspects compared to conventional materials such as rock wool, glass wool and extruded polystyrene. The conducted tests reveal that the mechanical performance of the mycelium-based composites depends more on the fibre processing (loose, chopped, pre-compressed, and tow), and size than on the chemical composition of the fibres. These experimental results show that mycelium-composites can fulfil the requirements of thermal insulation and have the potential to replace fosile-based composites. The methology used to evaluate the suitability and selection of organic waste-streams proved to be effective for the mycelium-material manufacturing applications.

Environmental pollution and scarcity of natural resources lead to an increased interest in developing more sustainable materials. For example, the traditional construction industry, which is largely based on the extraction of fossil fuels and raw materials, is called into question. A solution can be found in biologically augmented materials that are made by growing mycelium-forming fungal microorganisms on natural fibres rich in cellulose, hemicellulose and lignin. In this way, organic waste streams, such as agricultural waste, are valorised while creating a material that is biodegradable at the end of its life cyclea process that fits in the spirit of circular economy. Mycelium-based materials have properties that are promising for a wide range of applications, including the use as construction materials. Despite this promise, the applicability and the practicality of these materials are largely unexplored and moreover, individual studies use a wide range of different experimental approaches and non-standardized procedures. In this review, we critically evaluate existing data on the composition of mycelium-based materials and process variables with the aim of providing a comprehensive framework of the production process. The framework illustrates the many input factors during the production that have an impact on the final characteristics of the material, and the unique potential to deploy more tuneable levels in the fabrications process that can serve to prototype a diversity of new unprecedented applications. Furthermore, we determine the applicability of existing data and identify knowledge gaps. This framework is valuable in identifying standardized approaches for future studies and in informing the design and process of new applications of mycelium-based materials.

In the context of the ongoing transition from a linear to a circular economy, ecologically friendly renewable solutions are put in place. Filamentous fungi can be grown on various organic feedstocks and functionalized into a range of diverse material types which are biobased and thus more sustainable in terms of their production, use and recycling. Pure mycelium materials, consisting only of mycelial biomass, can adopt versatile properties and appear promising as a substitute for current petrochemically produced polymeric materials or, in the case of myco-leather, as a substitute for animal-based leather. In recent years, a handful of private companies have been innovating to bring products based on pure mycelium materials to the market while scientific interest in these promising biomaterials is now starting to gain momentum. In this primer, we introduce pure mycelium materials, frame different production methods, review existing and potential future applications, thereby offering a vision on future advances for this emerging fungi-based technology.

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