Fungus leather sheet

Fungus leather substitute offers greener alternative material

Image credit: Antoni Gandia (Mogu S.r.l.)

A “promising” fungal leather substitute that looks and feels like traditional leather could be more sustainable and cheaper than the animal and plastic versions currently favoured by manufacturers.

Traditional leather, typically made from animal hides such as cow and goat, brings ethical issues as well as the deforestation and greenhouse gas emissions associated with livestock farming. Treating animal hide to turn it into leather, known as tanning, often uses hazardous chemicals that can leach into the environment.

Leather alternatives, such as those made from plastic, are vegan in that they don’t use animal hides. However, traditional synthetic leather is made using the polymers polyurethane (PU) or polyvinyl chloride (PVC) which, like most other plastics, are made from fossil fuels and are not biodegradable.

In a new review paper, researchers at the University of Vienna, Imperial College London and RMIT University in Australia argue that leather made from fungi has “considerable potential” to be the best leather substitute in terms of sustainability and cost when compared to animal and plastic-derived versions.

The researchers say that producing fungi-based leather uses fewer hazardous chemicals and releases less extra carbon into the atmosphere, while the resulting fabric still looks and feels like traditional leather in terms of durability and flexibility. Fungal 'leather' (which could become known as 'fleather', just as plastics-derived alternatives are often called 'pleather') is also fully biodegradable when not combined with another material to make composite leather, so it can be safely disposed of without leaving any plastic footprint.

Professor Alexander Bismarck, study co-author from the University of Vienna and Imperial’s Department of Chemical Engineering, said: “We tend to think of synthetic leather, sometimes known as ‘vegan leather’, as being better for the environment. However, traditional leather might be ethically questionable and both leather and plastic substitutes have issues with environmental sustainability.

“Fungi-derived leather brings none of these issues to the table, and therefore has considerable potential to be one of the the best leather substitute in terms of sustainability and cost.”

Mushroom leather bag inline

Image credit: Antoni Gandia (Mogu S.r.l.)

Leather substitutes can be produced from fungi by upcycling low-cost agricultural and forestry by-products such as sawdust. These serve as feedstock on which to grow mycelium – a matted mass of elongated fungal threads that grows into a sheet. Within a few weeks, the fungal sheet can be harvested and physically and chemically treated by pressing and crosslinking to produce a material with a similar feel to animal leather. This material consists mainly of biodegradable chitin and glucan biopolymers.

The researchers say fungi-derived leather could be of particular interest to sustainability-conscious consumers and companies as well as to the vegan community and that the commercial and consumer appetite for bio-derived leather alternatives like those from fungi and cellulose is growing.

Dr Mitchell Jones, a co-author from the University of Vienna said: “Renewable, bio-derived clothing is a growing market and fungal leather is becoming a promising new frontrunner in the quest for sustainable and ethical clothing.”

The team's review examines the sustainability of animal and synthetic leathers and presents an overview of the first developments and commercialisation of leather substitutes derived from fungi.

According to the authors, one of the greatest challenges in the production of fungi-derived leather is in making consistently good quality mycelium sheets that exhibit uniform growth and consistent thickness, colour and mechanical properties.

Professor Bismarck said: “Substantial advances in fungi-based leathers and the growing number of companies that are producing them suggests that this new material will play a considerable role in the future of ethically and environmentally responsible fabrics.”

The team's findings have been published in an article titled 'Leather-like material biofabrication using fungi' by Mitchell Jones, Antoni Gandia, Sabu John and Alexander Bismarck, in Nature Sustainability.

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