Bolt Threads, originally named Refactored Materials, was founded in 2009 by Dan Widmaier, David Breslauer, and Ethan Mirsky to use biotechnological innovation to create materials. Dan Widmaier initially developed this idea during his Ph.D. in Chemical Biology. The company has since grown to a team of nearly 100 employees.
The company’s first material is a spider silk product called Microsilk. They recently expanded into making alternative leather from mycelium (Profile of Bolt Threads - Mylo) as well as a spider silk protein (B-Silk) for use in cosmetics. The first commercially available product was a 2017 limited edition of Microsilk ties. Bolt Threads then collaborated with Stella McCartney on a dress made with Microsilk fabric that was shown at the New York MoMA in October 2017. In July 2019, Stella McCartney and the Adidas company unveiled the Biofabric Tennis Dress, created with a Microsilk and cellulose-blend fiber and designed to be completely biodegradable.
Microsilk is made by using precision fermentation to grow the same protein spun by spiders. Because the protein is identical to spider silk’s protein, Microsilk has the same properties as spider silk, including strength, durability, and softness.
Bolt Threads uses the same precision fermentation technology that has been used for decades to produce insulin, vaccines, and other products. The company studied the specific proteins in spider silk and determined the genetic code necessary to produce those proteins. Putting that code into modified yeast cells and giving the yeast the necessary water and sugar allows them to produce protein via fermentation. This protein is then purified, spun, and knitted into fabrics.
Microsilk is protein and thus has the potential to biodegrade, unlike polyester and other synthetic fibers. Microsilk may be more sustainable on other measures, but comparison data is currently lacking. No animals are used in making Microsilk.
Because Microsilk is made of the same proteins as spider silk, it has the same properties, including strength, elasticity, and softness.
Images from Bolt Threads.