Adopting new materials offer a useful way of doing this, but what works in one sector is often poorly suited to others. Fungal mycelium could change that, according to researchers at the Fraunhofer Institute for Applied Polymer Research (IAP) in Potsdam, Germany, who are linking together disparate strands of materials development with the aim of providing sustainable, biodegradable options for everything from wallets and packaging to insulation.
When most people think of fungi, they think of the curved cap and stem of a mushroom. The largest part of the organism consists of a network of cell filaments called mycelium, however, which mainly spreads below ground and can reach much bigger sizes.
Although some projects have already explored use of mycelium-based materials, “this finely branched network has been underutilised,” according to the Fraunhofer team. The products are particularly promising for replacing petroleum-based products with natural, organic composites, they added.
“Faced with climate change and dwindling fossil raw materials, there is an urgent need for biodegradable materials that can be produced with lower energy consumption,” said Dr Hannes Hinneburg, a biotechnologist at Fraunhofer IAP.
Dr Hinneburg and his team are using mycelium, from sources including edible mushrooms or bracket fungi such as the oyster mushroom or tinder fungus, to transform plant residues into sustainable materials.
“The mycelium has properties that can be used to produce environmentally friendly, energy-efficient materials, since the growth of the fungi takes place under ambient conditions and CO2 remains stored in the residues. When cellulose and other organic residues decompose, a compact, three-dimensional network forms, enabling a self-sustaining structure to develop,” said Dr Hinneburg.
The process uses organic substrates such as cereal residues, wood chips, hemp, reeds, rape and other agricultural residues. These substances are a source of nutrients for the fungus, and are permeated entirely by a fine network of mycelia during the metabolic process. This produces a fully organic composite that can be made into the required shape and stabilised through thermal treatment.
“First, you mix water together with agricultural residues such as straw, wood chips and sawdust to form a mass. Once the level of humidity and particle size have been determined, and the subsequent heat treatment to kill off competing germs has been completed, the substrate is ready. It provides food for the fungi and is mixed with the mycelium.
“Following a growth phase of around two-to-three-weeks in the incubator, the mixture will produce – depending on the formulation and process used – a substance similar to leather, or a composite that can be processed further,” said Dr Hinneburg.
The fungal materials can reportedly be cultivated with a wide range of properties. Parameters including the type of fungus and agricultural residues, plus temperature, humidity and growth duration, can target properties such as durability, stretchability, tear resistance, elasticity, softness or porosity.
“The versatility of the material means it can take on a huge variety of forms, from thick blocks to wafer-thin layers,” an online announcement said. Fungus-based materials could be used in textile upholstery, packaging, furniture, bags or insulation boards for interiors, they added. When used as a construction material, the fungus primarily functions as a ‘biological adhesive’, as a wide range of organic particles are joined together via the mycelium.
“The many positive properties of the material – heat-insulating, electrically insulating, moisture-regulating and fire-resistant – enable an important step toward circular and climate-positive construction,” said Dr Hinneburg, one of whose current projects involves developing a novel polystyrene alternative for thermal insulation.
In another project, he is working alongside the German Institute for Food and Environmental Research and Agro Saarmund to produce environmentally-friendly, mycelium-based packaging trays, from residues and raw materials sourced from local agricultural and forestry activities. He has also developed the base material for animal-free alternatives to leather products such as bags and wallets.
A few companies in Europe are developing mycelium-based materials for commercial use, the researchers said, but challenges include access to the raw materials, the ability to ensure consistent product quality and the means to scale up activities.
To address these challenges, the team is using a newly developed roll-to-roll method, for which they have already created a prototype. “This method offers significant advantages over standard manufacturing processes involving boxes and shelving systems,” they claimed.
By using a standardised, continuous production method under controlled process conditions (such as temperature and humidity), the researchers aim to ensure that the products have consistent material properties. Resources can be used more efficiently, they added, and production could be scaled “to an industrial level”.
“This is crucial in order to meet growing industry demand for sustainable materials and to become less dependent on petroleum in the long term. Production can also be improved further by using innovative technologies such as artificial intelligence to optimise the combination of residues and types of fungi,” said Dr Hinneburg.
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