More Than Just Threads: Mushroom Leather

Continued Innovation at Bolt Threads

Bolt Threads followed up their silk with Mylo, an alternative to leather that is made from mushrooms.

David Breslauer ’05 and Bolt Threads began with silk, but have further designs on the applications of their tech. “I oversee our technology portfolio, as well as pursue what other new technologies we’re going to produce,” he says. “As time has gone on, we’ve really become a biomaterials company overall.”

Bolt Threads followed up its silk with Mylo, an alternative to leather that is made from mushrooms, or more specifically, the mycelium cells that make up the fungus’ branching underground structure. These particular cells grow as tiny threads that form vast networks under the forest floor.

“We engineered it to assemble into a supple yet durable material that can replace real and synthetic leather,” says Breslauer. Mylo can be produced in days versus the years it takes to produce animal leather, dramatically reducing the impact on the environment.

As for even more applications, Bolt Threads has applied its synthetic silk savvy to skincare. The spinoff company, Eighteen B, uses the tech to make a line of a “B-silk” protein-based moisturizers and creams.

The company applies the signature yeast fermentation process to produce and isolate “unhydrolyzed” or full-length silk protein chains, as opposed to the common practice of fragmenting proteins into smaller pieces, potentially compromising their protective qualities.

And where most skincare silk products are made from silkworm cocoon derivatives, Eighteen B’s spider-inspired silk protein is stronger and more elastic, thanks to a unique molecular makeup of repeating amino acids (18 of them, get it?).