Commonly made from the skin of cows, sheep, or pigs, the versatility and reliability of leather has made it a staple textile used in clothing, footwear, furniture, accessories, and much more. Given its popularity, the market value of leather is expected to reach $360 billion by 2025. However, the process of tanning and chemically treating animal hides is environmentally unsustainable, with both direct and indirect relationships to chemical and waste pollution, deforestation, and greenhouse gas emissions. 

In recent years, mycelium — the branching underground network that fungi species use — has gained significant attention because of its applications in everything from food to material innovation. Because of its low production costs and versatility, some experts believe mycelium could potentially replace animal-based leathers. 

In this study, researchers compiled data on the chemistry and biology of mycelium-based products and compared the environmental footprint involved in producing mycelium-based leather to animal-based and synthetic leather. To do this, they used data from the Higg Materials Sustainability Index. 

Overall, the authors found that synthetic leather only has a quarter of the environmental impact of animal-based leather. Because synthetic leather does not require animal farming, it doesn’t contribute to issues like global warming, intensive water use, and eutrophication (chemical pollution that negatively affects aquatic ecosystems) on the same scale that animal-based leathers do. However, processing synthetic leather requires almost the same amount of fossil fuels and chemicals as animal leather, making synthetic leather an incomplete and unsustainable solution.

Compared to synthetic and animal-based leather, manufacturing mycelium leather requires few direct energy inputs beyond sterilization. Once grown, mycelium can be treated with chemicals like vinegar and alcohol to produce leather. Because of this simple production process, manufacturing raw sheets of unprocessed mycelium is much cheaper than creating synthetic or traditional leather. A square meter of raw mycelium costs between 18 cents and 28 cents to produce, while the same amount for raw animal hides would run between $5.81-$6.24, and anywhere between $4.43-$23.30 for synthetics.

To compare the performance of mycelium-based leather against animal-based and synthetic leather, the researchers tested their flexibility and durability. Mycelium and synthetic leather have similar levels of durability, and both were found to be less durable than animal-based leather. However, when mycelium leather was treated with a special coating (polylactic acid), it improved its tear and flex strength to become more than twice as strong as animal-based leather. The study found that mycelium-based leather also resists fading, color tarnishing, and handles water/sweat exposure almost as well as animal leather. 

Although mycelium leather shows promising results, there are still challenges in producing it. Mycelium is typically made by growing fungi on beds of sawdust and organic waste, and then compressing the beds into mats. However, mycelium can grow unevenly, giving the finished mats inconsistent layers. This can result in lower performance and strength when using mycelium in things like leather. Better control over growth conditions, new processing techniques, and genetic engineering can potentially solve these shortcomings.

It’s important to note that the demand for non-animal leather is still developing. While the leather industry as a whole is expected to reach $360 billion by 2025, synthetic leather only makes up about $20 billion of it, and many consumers still prefer animal-based leather for its texture, performance, and convenience. Non-animal leathers are rapidly growing in popularity, though, and the researchers predict that the market for artificial leathers will grow more than 25% by 2025. 

The growing popularity of mycelium-based products makes it one of the top contenders against traditional leather, and the data from this study suggest it’s cheaper and more beneficial for the environment. Besides fashion, the authors point out that mycelium is now also being used to create animal-free construction products, packaging, and food. Although research still needs to be done before mycelium leather can consistently produce strong and reliable products, the future for mycelium and for alternative leather seems promising. To push society further away from leather and other animal products, advocates can encourage manufacturers and researchers to explore the use of mycelium.