In conversation with Bolt Threads


From silk proteins to mycelium, Bolt Threads have been at the forefront of material innovation since its inception in 2009. We caught up with the founders, David Breslauer and Dan Widmaier to discover the history of Bolt Treads and their most recent material innovations.


How did you start Bolt Threads?

We founded Bolt Threads in 2009. I was working on microfluidic devices during my PhD at UC Berkeley in the mid 2000s. People had dissected spiders and knew the mechanisms of how spiders extrude silk, but I wanted to replicate that on a microfluidic device. I wanted to mimic a silk gland, and was looking for silk to use in his device and test extrusion “on chip.” I was then introduced to a professor at UCSF who was supposedly making “microorganisms that spin silk fibres.” The professor told me he could get silk (made from microorganisms), and sent me an academic paper his students, and my now co-founders, Dan Widmaier and Ethan Mirsky were publishing. Dan and Ethan replied to me that the vials of silk they were producing had a lot of contaminants, and making silk wasn’t as easy as it seemed. From there, we were excited about the work we could do together.

-- David Breslauer, Chief Science Officer (CSO) and Co-Founder


Today, Bolt Threads is a materials innovation company, and using proprietary technology and revolutionary bio-engineering concepts, we are able to transform the world around us, beginning with the textiles found and used in our everyday lives. We’re working to create the next generation of performance fibres and fabrics with our first breakthrough being the Boltspun necktie - our first-ever commercial product made of our Microsilk, which launched in March 2017. This April, we introduced our second material Mylo™ - the first commercially available leather grown from mycelium, the root structure of a mushroom. Both materials embody the beginning of a new way to make sustainable, high-performance materials with customized properties that can be produced at a commercial scale through viable cost for widespread use in consumer products - something no one else has done.

-- Dan Widmaier, CEO and Co-Founder


What processes did you go through to develop MicroSilk?

Bolt Threads is a materials innovation company at its core, but was born out of curiosity for natural spider silk, our first material, and the idea of engineering protein materials in a sustainable way - beginning with textiles used in our everyday lives. We’re proud of what we’ve been able to achieve in terms of the technology we’ve built through both our Microsilk and Mylo™ materials, but we’ve always known that in order to reach our full potential, we need the right channels - brands who excel in reaching consumers in tangible, meaningful ways. With that and our vision for the future of textile manufacturing, we seek to improve apparel production, especially within the fashion industry.


In July of last year, we announced a long-term partnership with Stella McCartney. Combining Stella’s relentless pursuit of sustainable materials with our proprietary breakthroughs in industrial biotechnology, our partnership represents a step-change for the future of apparel production, and the fashion industry at large. From the day we founded Bolt Threads, we’ve dreamt of partnering with Stella McCartney. Not only does she have an unparalleled aesthetic, but her values and pioneering sustainable fashion align perfectly with our vision for the future of fashion.


We also acquired Best Made Co., an apparel and lifestyle brand, committed to craftsmanship, functionality and quality. They, too, have a significant appreciation for innovative materials and understand the endless possibilities that biofabrics can bring to further advance product design. In December, we launched our first co-created product and Bolt Threads’ second commercial product to-date - the Best Made Microsilk Cap of Courage. In addition to introducing new products featuring our Microsilk, we also are working hand-in-hand with the team on other design projects.

-- Dan Widmaier, CEO and Co-Founder


What are the characteristics of spider silk and which industry sectors do you see the material being used in?

We wholly engineer and produce silk protein, primarily using the ingredients of sugar, yeast, and water. We study silk proteins found in nature to determine what gives them their incredible properties. Then, we develop proteins inspired by these natural silks by putting genes into yeast. Using proprietary technology and a fermentation process, it turns the protein into a fibre following a wet-spinning process. From there, the fibre is built into silk strands that can be knitted. There are no spiders involved at all in the process. We originally studied real spiders’ silk to understand the relationship between the spiders’ DNA and the characteristics of the fibres they make. Today’s technology allows us to make those proteins without using spiders.


Microsilk has the potential to be tuned for desired qualities, like stretch or water-resistance. As we continue Microsilk development, we can vary the protein sequences that make up the fibre to minimize or maximize physical properties of our choice, so the material can be used across a variety of industries as needed. We’re focused mainly on improving the fashion and material manufacturing industries and making the production processes more sustainable.

-- David Breslauer, Chief Science Officer (CSO) and Co-Founder


What are you looking forward to in the next six months?

We’re thrilled to have announced our second material to the world Mylo™ - the first commercially available leather grown from mycelium, the root structure of a mushroom - this April. Bolt Threads is the first company in decades to release two novel materials, the first being our biofabricated Microsilk™. We partnered with biomaterials company Ecovative to license the initial mycelium technology, and then perfect the process for commercial viability. Mylo™ looks and feels like hand-crafted leather, and because we can control the environment and process through which Mylo™ is grown, we’re able to manipulate the leather’s properties - durability, strength, and suppleness - making each product truly one-of-a-kind. We’re excited to be bringing Mylo™ to consumers by releasing our own bag available for pre-order this June. Additionally, our partner Stella McCartney debuted the Mylo™ Falabella Prototype 1 bag at the Victoria and Albert Museum’s “Fashioned from Nature” exhibit this April in London.

-- Dan Widmaier, CEO and Co-Founder


What challenges are you facing at the moment?

Right now, we’re focused on improving our manufacturing process in order to maintain the highest possible level of quality, at scale. It’s hard work but we’ve been able to get there with our first necktie, which launched last March, and the Microsilk Cap of Courage with Best Made Co. that launched in December, and are planning to launch a Mylo™ bag, available for pre-order in June.

-- David Breslauer, Chief Science Officer (CSO) and Co-Founder


Where do you see Bolt Threads in five years time?

Bolt Threads is dedicated to making better materials for a better world. We know Microsilk™ and Mylo™ are a part of that future, and we’re thrilled to be bringing both to market and proud of what we can create. We are also actively working on, and seeking out, other technologies that fulfil that mission. Right now, we’re focused on refining our Microsilk-making and Mylo™ production processes and creating meaningful products for consumers through our brands and partners; but as an innovative material company, we’re always looking for inspiration in nature to create additional sustainable materials.

-- Dan Widmaier, CEO and Co-Founder


To find out more about Bolt Threads, take a look at their website



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