For decades, fungi in biotechnology have mainly been valued as producers. They provide us medicines like penicillin, along with enzymes, chemicals, and alcohol. In this role, fungi have largely been treated as tools, with attention focused on the substances they create. Now, research is opening a new chapter. The question is no longer just what fungi can produce, but what can be made from the fungi themselves, especially their mycelium.

The mycelium is the fine, thread-like network that forms the main body of a fungus. In nature, it grows through organic matter such as plant debris and wood. It consists of tubular cells, known as hyphae, and releases enzymes that break down and transform organic material. These properties make fungal mycelium a promising basis for new products. Its structure and natural behavior can be harnessed to create innovative, sustainable alternatives. One example of this emerging field is mycomaterials.

Fungal mycelium in search of new nutrients. Photo: MyPilz

What are mycelium-based materials?

In practice, the process is relatively simple. The mycelium is cultivated on agricultural waste materials such as straw or sawdust, within molds or containers of a desired shape. As it grows, the hyphae penetrate the substrate and act as a natural binder, effectively ‘gluing’ the particles into a solid composite. The result is a lightweight, mechanically stable, and fully biodegradable material.

To produce a finished mycelium material, the growth process must then be stopped through heating and drying. Temperatures below 60°C are typically used to halt further growth. However, these conditions do not always kill the fungus completely. This becomes relevant when non-native species are used and the final products are later composted.

Surface of a mycelium material prototype from MyPilz with mycelium of a hairy turkey tail (Trametes hirsuta) from Styria. Photo: MyPilz

This approach has already been used to create a wide range of products, including sound absorbers, insulation boards, climbing holds, and even coffins. In addition, pilot projects have explored the use of mycelium-based materials for entire building components and structural elements. The properties of these materials, such as strength, density, and thermal insulation, have been evaluated against conventional materials like polystyrene, foams, plywood, and fiberglass. These comparisons show that performance varies significantly depending on the fungal species, the substrate, and the specific processing.

Ecology meets material performance

While the choice of fungal species clearly plays a crucial role, the extent of these differences and the underlying biological mechanisms are still being studied. Fungal hyphae have cell walls composed of natural building blocks such as glucans and chitin, which provide both stability and flexibility. They also contain proteins, carbohydrates, pigments, and minerals. The exact composition varies between species and directly influences the resulting material properties.

The tinder fungus (Fomes fomentarius). Photo: MyPilz

A clear example is the tinder fungus (Fomes fomentarius). Its fruiting body features a hard, resilient outer layer and a soft, porous inner tissue. Although both structures are composed of mycelium and hyphae, they differ significantly in their mechanical properties. These differences are closely linked to variations in cell wall composition.

In addition to the chemical composition of the cell wall, the type and arrangement of hyphae also play a key role in determining material properties. Fungal structures are generally classified into three basic hyphal systems: monomitic, dimitic, and trimitic. Monomitic systems consist exclusively of generative hyphae, which are thin-walled and highly branched. They are typical of fungi such as the oyster mushroom (Pleurotus ostreatus) or the split gill (Schizophyllum commune). Dimitic systems include, in addition, thick-walled skeletal hyphae that provide increased strength, as seen in species like the hairy turkey tail (Trametes hirsuta). Trimitic systems also contain binding hyphae, which create particularly dense and resilient structures. This type is found in fungi such as the tinder fungus (Fomes fomentarius) and the reishi mushroom (Ganoderma lucidum).

The hyphal system is not entirely fixed but can be influenced by the substrate and growth conditions. Nevertheless, studies show that hyphal type has a significant impact on the properties of mycelium-based materials. Materials derived from trimitic systems are generally denser, more robust, and penetrate the substrate more extensively than those from monomitic systems.

Examples of fungi with their respective hyphal systems. Source: Hernando, A. V., et al. 2024. Photos: Pixabay

Although the influence of fungal species on material properties is well recognized, a systematic comparison has long been lacking, as previous studies often relied on different substrates or measurement methods. A recent study by Wildman et al. helps address this gap by systematically comparing seventeen fungal species grown on the same substrate. The researchers observed clear aesthetic differences between species, including variations in colour, texture, and the formation of a dense outer skin on the material surface.

Significant differences were also found in thermal conductivity, a key parameter for insulation materials. The lowest value, 0.0376 ± 0.0006 W/m·K, was measured for the chestnut mushroom (Pholiota adiposa) while the highest value, 0.0451 ± 0.001 W/m·K, was recorded for the tiger sawgill (Lentinus tigrinus). For comparison, conventional insulation materials such as glass wool and polystyrene typically range between 0.03 and 0.04 W/m·K. Thermal conductivity was found to correlate with material density. In addition, infrared spectroscopy revealed species-specific differences in chemical composition, which might be linked to variations in enzyme activity and substrate degradation behavior. Overall, the study shows that the choice of fungal species has a substantial impact on key material properties and highlights the need for further research to better understand the underlying mechanisms.

The role of growth conditions

Not only the fungal species but also the surrounding environmental conditions play a crucial role. Fungi respond sensitively to factors such as substrate composition, oxygen availability, CO₂ levels, moisture, and light. These parameters influence metabolism, growth rate, and enzyme production. A study by Kijpornyongpan et al. demonstrated that the same fungal species produces different sets of enzymes depending on the substrate. Since enzyme activity determines how extensively the substrate is degraded and how densely the mycelium develops, this has direct consequences for material production. As a result, the same fungus can yield materials with different densities and water repellency when grown on different substrates.

Targeted modification of properties

In addition to selecting fungal species and adjusting growth conditions, genetic engineering offers another lever to tailor material properties. In the split gill mushroom (Schizophyllum commune), for example, the gene sC3 has been deactivated. This gene controls the production of a hydrophobin, a protein that influences the water repellency of the cell surface. Materials derived from the modified strain exhibited properties more similar to synthetic polymers, while those from the unmodified strain retained characteristics closer to natural materials.

The turkey tail mushroom (Trametes versicolor). Photo: MyPilz

Genetic engineering is a powerful tool, but it also presents significant challenges. For many fungal species, complete genome sequences and well-established molecular biology methods are still lacking. In addition, genetically modified organisms are subject to strict regulatory requirements. This becomes particularly relevant when resistance genes are introduced, as any potential transfer of these genes to other organisms must be prevented. As a result, materials produced from such strains must be fully inactivated before use or disposal to avoid environmental release. This additional processing increases energy use and may reduce overall sustainability.

The potential of natural diversity

Most current approaches, whether based on substrate optimization or genetic engineering, focus on already known species. In doing so, a vast amount of untapped potential is often overlooked. It is estimated that only around 4% of all fungal species have been scientifically described to date. So far, roughly 70 species have been systematically studied in mycelium-based material research, with Pleurotus ostreatus, Ganoderma lucidum and Trametes versicolor among the most commonly used. This highlights how limited the current scope still is. In reality, millions of fungal species are likely undiscovered or insufficiently characterized. Each species has its own cell wall structure, growth pattern, and enzyme profile, all of which influence material properties. Instead of further optimizing a small set of well-known species, it may therefore be equally, or even more, promising to explore new species that naturally exhibit the desired characteristics.

Our approach at MyPilz

This is exactly where MyPilz comes in. We deliberately leverage natural diversity. We isolate new fungal strains directly from nature, with particular attention to those adapted to local substrates. These strains are then purified, characterized, and systematically tested across a range of applications. We work closely with companies and startups aiming to develop new materials, optimize existing processes, or create functional prototypes. Our goal is to identify the most biologically suitable strain for each application and unlock its potential without relying solely on genetic engineering. In many cases, the solution for future materials may already be growing in the soil or forest just outside your door.