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Biotech leather struggles

Bolt Threads halts production, and Modern Meadow adds plastics

by Craig Bettenhausen
July 6, 2023 | A version of this story appeared in Volume 101, Issue 22


A black half-circle-shaped purse with a gold and silver chain, the material looks like leather with a satin finish.
Credit: Stella McCartney
Fashion designer Stella McCartney made these handbags in 2022 with mushroom mycelium leather from Bolt Threads, but in a limited commercial run of 100.

Two prominent names in the field of vegan, biobased leather are showing signs of trouble. Bolt Threads, one of C&EN’s 10 Start-Ups to Watch in 2015, has stopped production of Mylo, the leather-like material it makes from mushroom mycelium. And cell-culture specialist Modern Meadow is turning to a synthetic polymer substrate as it readies the rollout of its leather-like material.

Bolt Threads CEO Dan Widmaier told Vogue Business that despite partnerships with the luxury goods makers Stella McCartney and Kering, as well as the sporting goods brands Adidas and Lululemon, Bolt was unable to secure the investments it needed to continue with Mylo, at least for now.

As recently as 2021, Bolt was expanding rapidly and preparing commercial-scale production facilities. In 2022, the firm brought in collaborator Ginkgo Bioworks to help with strain optimization and engineering. Bolt says it is continuing to develop its original product, spider-silk protein made in transgenic yeast.

Separately, Modern Meadow announced that Bio-VERA, the leather alternative it is developing, will be made by coating its cultured biomaterial onto a synthetic polyamide backing material from BASF.

BASF will include mass-balance credits for recycled content with the polyamide fabric it provides to Modern Meadow. Though the deal is likely to help the material reach commercial scale faster, it means the product will not be fully biobased or fully biodegradable.


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