From fungi to fashion: Mushroom eco-leather is moving towards the mainstream

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(Left) Ganoderma lucidum (rishi) grown in aluminum trays with clear plastic lids, (Middle) Large mat of Ganoderma lucidum (rishi) being harvested by peeling, (Right) Mycelium mat after harvesting and rinsing the remains of the growing medium . Credit: Research directions: biotechnology design (2024). DOI: 10.1017/btd.2024.6

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(Left) Ganoderma lucidum (rishi) grown in aluminum trays with clear plastic lids, (Middle) Large mat of Ganoderma lucidum (rishi) being harvested by peeling, (Right) Mycelium mat after harvesting and rinsing the remains of the growing medium . Credit: Research directions: biotechnology design (2024). DOI: 10.1017/btd.2024.6

As fashion designers look for alternatives to leather, growing mycelium (or fungus-based) ‘leather’ substitutes using a new paste medium has opened up the possibility of growing this biofabricated material more quickly and easily.

Researchers investigating how to grow and cultivate mycelium leather more effectively tested their hypotheses by growing and harvesting mycelium leather mats using a new paste of their own design as a substrate. Their findings have been published in Research directions: biotechnology design.

Mycelium materials offer a low-cost and environmentally sustainable alternative to some petroleum-based materials and a more sustainable and ethical alternative to animal leather. They can be grown on a wide variety of organic agricultural and industrial wastes or side streams.

With greater adoption and scale of production, these products have the potential to become more economically viable than established traditional materials. They can also be optimized to meet consumer demands.

The researchers investigated the compatibility of mushrooms for the development of leather mats using two fungal species: Ganoderma lucidum (reishi), a medicinal mushroom widely used in bio-design; and Pleurotus djamor (pink oyster), a gourmet mushroom that tends to quickly colonize the substrate and enter the fruiting phase, meaning it quickly produces mushroom fruiting bodies.

By carefully formulating a new paste substrate in which the mushrooms can grow, the researchers sought to improve the availability of nutrients from the mushrooms; enable their scalability; and streamline their cultivation processes.

Different types of mushrooms have their own substrate preferences, which means that a large part of growing mushrooms (and mycelial leather) involves matching mushrooms with the best available substrate. Common substrates include straw, coffee grounds and manure.


Tensile testing of mycelium samples using Mxmoonfree Digital Force Gauge 500N. Credit: Research directions: biotechnology design (2024). DOI: 10.1017/btd.2024.6

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Tensile testing of mycelium samples using Mxmoonfree Digital Force Gauge 500N. Credit: Research directions: biotechnology design (2024). DOI: 10.1017/btd.2024.6

Mycelial leather is produced by growing the fungus as a biological tissue or mat on a liquid or solid substrate, or as fungal biomass in submerged liquid fermentation. Solid state fermentation provides superior growing conditions; However, liquid state surface fermentation allows mycelial mats to be harvested more easily, although the growth rate is slower due to the lower oxygen level. Finally, liquid state fermentation gives improved yields, but the product requires further manipulation to produce a mycelial mat.

In response to these challenges, the researchers developed a new cultivation method based on a paste consistency substrate that offers the advantages of high nutrient content and small particle size, which promotes nutrient absorption.

The researchers found that by using this specific paste they were able to grow thicker mycelial mats in a shorter time compared to growing on nutrient-enriched agar or liquid culture. Furthermore, further benefits of this growing method became apparent during the harvest stage, as the mats had become so strong that it was possible to peel them without having to cut the skin.

Lead author of the study Assia Crawford, from the University of Colorado in the United States, said: “As our world looks for sustainable alternatives to traditional materials, there is growing interest in using living organisms to produce biodegradable material substitutes with a low impact on the environment —such as mycelium leather, an environmentally friendly leather alternative.

“The extensive treatment required to convert hides into traditional leather comes at a high environmental cost. In addition, petrochemical alternatives such as artificial leather, which have become increasingly popular in response to the challenges of animal leather production and associated ethical concerns, including significant environmental impacts with fossil fuel extraction, long degradation periods and the potential risks of degassing. Developing better alternatives is crucial in today’s environmentally fragile world.

“Biodesign methods such as those explored in our study contribute to the development of high-performance, scalable, biodegradable material alternatives. These in turn have the potential to address the environmental challenges of high textile consumption. In fact, the flexible nature of pure mycelium mats is a compelling potential alternative to non-woven materials such as animal leather and petroleum-based faux leather alternatives.

“As researchers, we have a responsibility to continue developing better materials in response to the climate crisis, and that is what the study aims to do.”

More information:
Assia Crawford et al., Growing mycelium leather: a paste-substrate approach with post-treatments, Research directions: biotechnology design (2024). DOI: 10.1017/btd.2024.6

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