Meet Bolt Threads: A Fungal Materials Company
A milestone for mycelium has emerged. Adidas has partnered with Bolt threads, a biomaterials company, to use mycelium in their Stan Smith Mylo Edition shoes. Built with biology, crafted with humanity— Bolt Threads is pioneering the use of fungal materials into industrial commodities, and it's not something their team takes lightly. Today we are joined by the co-founder of Bolt Threads, Dr. David Breslauer, to discuss the philosophy and methodology behind their important contributions and innovative products.
- Fundamentals in fungal biotech
- Biomimicry in materials science
- The company history and culture of Bolt Threads
- Engineering yeast to make a spider silk-like protein
- Silk as a base protein for innovative materials
- Emergence of germ theory from silkworm factories
- The industry of biomaterials: how do you scale a material or product to make a real difference?
- Mycelium leather — its performance, sustainability, engineer-ability and aesthetics
- Filamentous fungi in biotech and how it differs from yeasts
Stan Smith Mylo: https://www.youtube.com/watch?v=R__xk0-z7lg
Bolt Threads: https://boltthreads.com/
Spider silk mechanics: https://www.youtube.com/watch?v=xossR6eHv3I
Germ theory: https://asm.org/Articles/2019/December/Sick-or-Silk-How-Silkworms-Spun-the-Germ-Theory-of
You're listening to the mushroom revival podcast.
Today on the show, we're getting physical. If you're trying to read fungi in your fit, this is an episode for you. fungal shoes, skincare shirts, hats, you name it.
That's right, y'all. We're talking about fungal materials, once again, be it a metabolite from the fungus or the fungus itself. Both threads is a materials solution company that looks to nature for pre existing technologies that they can implement into the modern day.
I'm David Breslauer. I'm the Chief Science Officer and one of the cofounders of bolt threads. Thank you so much for having me.
They work with fungi to create bio based materials like the fungi leather used in the Stan Smith Milo by Adi das, or the unlike other garments at Stella McCartney. So we've covered fungal materials in the show before highlighting mycelium composites foams dyes, but perhaps most sensationally leather.
There are actually a number of biotech companies that are working on this magical material, both threads being one of them. They're an industry leader, and quite eclectic when it comes to creating new materials beyond fungal textiles.
I think the way you described it is it's really appropriate. You said it's quite eclectic. And when you hear the background story, it makes a little more sense. Why? Because we didn't start the company with the idea that we were going to make be making a leather alternative, let alone a mushroom a mycelium base leather leather alternative, but ended up with a variety of product offerings. I was a graduate student at UC Berkeley working on my PhD in bioengineering. And at the time, a very hot topic of study was biomimicry. What can we learn from nature to improve our own engineering designs. And I got fascinated by spider silk. There were tons of spiders outside the women's faculty club at UC Berkeley. And spider silk was well known to be a very light and strong material. But I think what was more fascinating to me in particular, was just, yes, it's a great material, but also this tiny little organism makes it eats, flies, and so readily makes these fibers. And I started studying that process and looking into it, and became very quickly taken by these sort of orchestration and the interface of all these biological processes that lead that leads to an outcome that is this fibers of spider makes these proteins, these proteins have special structures, this protein stick to each other, and then they fold and they go from a liquid to a solid into a fiber that makes up a web.And I was studying that extensively.But it was a very hard problem to investigate, because I didn't have a large source of spider silk protein. You know, there's, there's no vat of spider silk protein out there that you can get. And someone said to me, You know, there's some people at UCSF, UC San Francisco, right across the bay working on exactly that for their graduate thesis. So to make a long story short, I met those guys. And they said, Yeah, we're trying to work on the opposite problem. How do you make that vat of polar? You're trying to work on how do you turn it into something useful? Let's Let's work together. And we got to talking. And we thought we had an idea for how to make scalable spider silk. We didn't know what we were going to use it for yet. We had a lot of thoughts, but we applied for some government grants. And there's a lot of motivation, because it's a unique material, and we got them. So we started the company, bolt threads. It wasn't called bolt threads at the time, but we can get into that. So here's where things took an interesting turn. We were as we were building up the science, we were also trying to build up the business case. And we kept debating iterating trying to figure out where could this fiber be used? And one day my co founder actually came and said, What if we made silk? We know silk is used in apparel. What if we started by saying we can make vegan, more sustainable silk at a consistent price point over time. And that was a pivotal moment because it was when we started studying apparel really. And we became much more focused on the products and the problems in technology and apparel. Then necessarily spider silk as a singular tool. And that's really what launched our sort of obsession with sustainability and sustainable materials versus just a compelling interest in them really digging deep and seeing where the problems in the apparel space were. And the problems with our materials, and then suddenly go, Wait, there's all these tools in nature, there's all these materials that have evolved things that we have not cultivated as a society or an industry. In the same way we have others that we believe we have the tools now to grow and scale in a more sustainable way than the existing materials. And that's how we ended up with such an eclectic mix of products.
So when you walk face first into a spiderweb, we've all been there, and then a crazy panic trying to quickly as humanly possible, pull off the 1000s of invisible threads off your face before spider bite, too. You probably aren't thinking to yourself, wow, this would be a great material for my clothing.
But in fact, it has some amazing properties. spider silk is thinner than human hair stronger than steel, more flexible than nylon. It's also anti microbial and could have some pretty awesome medical applications. So why not just raise an army of spiders and harvest their silk? Well, for one thing, they don't make a lot of silk. And they actually tend to eat their webs when they're through with it. They also tend to eat each other spiders are territorial. And if you attempted to farm them, and close proximities or within any kind of reasonable fashion, they would probably kill each other before you could ever harvest enough so to justify your means.
But we do harvest the silky secretions from another arthropod silkworms and humans have been doing so for 1000s of years, it's just a bummer, because spider silk is stronger in structure. And therefore scientists and engineers have not given up on trying to get bacteria or in the case of both threads yeast to produce a comparable protein. Now it's kind of full circle, because in the boom of the silk industry, a parasitic fungi was attacking the silk worms, and was actually the beginning of germ theory. Now coming many years later, we get fungi actually helping to create silk. And so we're really coming full circle.
David, can you paint the picture for us on how you're creating your Microsoft? I mean, what does this actually look like?
Yeah, for this spider silk process, where we make two things one micro silk, our silk fiber and be silk protein, which is actually spider silk. Like polymer, it's it's almost just like spider silk. And it's protein that has tremendous functionality in personal care products thatemulate and can really replace or reduce the need for a lot of petroleum based ingredients. So you know, there's a ton of things you can do with with proteins by custom designing them. And it turns out to be that silk is a phenomenal template by which to make structural proteins. So people had sequenced spider silk genes for a while. And right around the same time, we founded the first full length spider silk gene had come out these genes, the genes, and the proteins for spider silk are shockingly complex, they tend to break a lot of conventional tools in molecular biology. And so the core technology we had was, we had developed this ability to assemble the DNA that is otherwise not conventionally assemble and put it in a micro organism and get that microorganism to make protein. Now, again, people have been making custom proteins with microorganisms since whether it's bacteria or yeast, since like the 70s, this is where we get insulin from. But silk has always presented a unique challenge, in that it's this really big protein that tends to fold in on itself and be very hard to unfold. So it tends to either choke the organism that's trying to make it or it's very makes the the organism makes very little of it, there are tons of different challenges. And so we had sermonette surmounted a lot of those, but really, our process quite simply is design the protein you want, order the DNA to make it up. That's actually its own industry. Now, that didn't exist that barely existed when we started but exists where you could just order DNA and put it in the microbe brew it up like beer, but instead of making alcohol it makes protein, or spider silk protein, purify up that protein, and then we have a powder. And depending on what we're making with that, we can actually process that protein. You can use it directly depending on what material you're making directly as an ingredient in personal care for fibers, we compound it and extrude it. So kind of like a playdough spaghetti maker or a showerhead, the fibers comes streaming right out. And that's how we get those materials.
So you, you literally just push it through a porous structure, and it will embody a thread. Yeah.That's really cool.
And one of the big learnings interestingly, to go back to the founding story was, I had spent so long studying how the spider did it, which is extraordinarily elegant, and evolution in nature, teach us so much there. But then what I had to really accept and learn as we built the company is, the end of the day, a spider does not make silk, particularly quickly, to make something that's cost effective, or that scalable, you can actually deliver to people. And at the end of the day, that means also to make a difference make an impact in terms of sustainability on the planet, you need to be extruding or making your fiber at a lot faster than the spider makes it so it's it required some marine learning to go from how can you both appreciate the beauty that is what nature evolved but also be comfortable using it as inspiration not one to one mimetics? And last question on the micro silk How does this perform compared to silk from silk worms nearly identically. Um, one of our big focuses in the beginning was to figure out how to make silkworm silk but easier to die, because that's one of the huge water sinks in the silkworm silk process, let alone growing the mulberry leaves that feed the silkworms and then make it machine washable, because that's something that limits silkworm silk, in terms of usage on top of costs, So ultimately, lowering the price point is makes it more valuable or more quickly adoptable. And so that's been our focus for apparel, there are other people who are working on using silkworm silk like or sorry spider silk like fibers for industrial applications, and medical applications. We never quite went that route, because it's a whole that's a whole different business and a whole different set of expertise. And I don't know that we would have ever ended up making Milo our mushroom leather. If we if we had gone that direction. It's sort of interesting to think back and play that story. We were very much focused on consumer apparel and how materials could be used there. For centuries, I say we were obsessed with consumer apparel. It's true, we were obsessed with consumer apparel, we developed a lot of knowledge and understanding about how to make consumer products. And what I mean by that is there's a certain aesthetic a component, a desire that the user has or a need for the for the user to have a desire that we had to really learn to work with and be comfortable with it scientists and we stumbled into personal care somewhat accidentally.
Experimentation leads to happy accidents. Both threads be silk once a protein reject is now one of their top products. Thanks to an observational scientist on the bolt threads team.
One day in iterating our different fibers, we accidentally made a fiber that soaked up way too much water just far too much water to be useful as a fiber. And one of our scientists she had explored spent her PhD exploring the use of silkworm silk for medical devices and had even considered spinning out from her graduate work accompany on using silkworm silk in personal care products and beauty products. And she started playing with that material that we had made because it was so water absorbing inside skincare products and discovered that you know, it had a very unique attributes that were hard to describe. But it was a film former it was biodegradable. It had an aesthetic it you could see my hands, you'd see my fingers rubbing against each other It had a smoothness without being oily. And so we started talking to more and more experts in the area. And we got a ton of positive feedback where people were saying, you know, you have a bio based and biodegradable ingredient that seems to provide an aesthetic a handfeel I don't even know all the words in the space and we have a business unit for this now that petroleum products either don't or we have to use a lot of them to get this appeal and people are trying to get away from synthetic polymers in personal particularly things that bioaccumulate meaning they don't biodegrade, they just go down the drain and fill our waterways and oceans and they and they stay there for a long time or the length, the time they've been on your face and so it suddenly created this business unit for us that were people were interested and are buying you can actually one of our more popular products is Vega more it's our partners is Vega Moore, who makes it a shampoo and conditioner and growths in hair growth serum with B silk that is doing incredibly well. And it uses B silk as an alternative to silicones and haircare products that has a lot of the properties of synthetics without being synthetics, but it turned does turn out that be silk, when used in skincare products has a positive impact on wound healing on your face. It's a positive impact on pollution prevention, because it's a film former so it makes a light film that that is basically protective. And then on haircare it allows you it's basically like a smoothing agent on your hair because it tends to adhere to your hair even after washing. And that's again, that's a hard feature to get necessarily with while also feeling good and natural. With synthetics.
Yeast is at it again, it's so hard to pick a favorite application for use because it's so versatile and a relatively easy to engineer organism. It's been a star child of fungal biotech ever since we started working with it. But what I'm so excited about is the implementation of filamentous. fungi. This group of fungi are very different from yeast and that it grows the cells stick together. It's that fluffy white mycelium we all know and love. Companies like both threads are for the first time using the organism itself as the material, not the metabolite or compound that it secretes.
And this is incredible news for sustainable leather. Alternative leathers have been made from a variety of non animal products. But nothing seems to be satisfactory enough for the industry until mycelium showed up. And we're seeing giant corporations like Adidas pledge to use fungi in lieu of animal leather and petroleum based vegan alternatives.
When we started talking to a lot of brands about our micro silk product, the feedback we were we were getting quite often was silk is cool. We like this product. Our biggest priority, though, in terms of sustainability is leather. There was a there was a growing amount of pressure on brands that use leather, which is a lot of luxury brands and a lot a lot of footwear brands that not just had grown from an issue about animal rights and a sort of vegetarian vegan issue to also broadly a climate change issue with livestock animal agriculture being a huge contributor to greenhouse gas, and it was becoming impossible for for anybody to ignore. And so people kept saying to us, like, do you have a leather offering? Do you have a leather offering? And we had talked about it? My co founder Dan and I how we would do it? Could we use silk to make it leather is largely composed of collagen? Could we use our our protein expression platform to make collagen and process that into leather? I mean, it seems from a technological perspective, it seems like the intuitive thing to do. But we had done enough work with making films out of our materials and experienced enough with trying to make films out of collagen, to just say, you know, like this isn't gonna make a leather like material. And when we look at what is leather, why do people like leather, you look at it. It's this intricate structure. It's quite amazing. I mean, it's skin, like let's remember its skin and it's so it's this thin layer with fiducials at multiple scales, macro micro nano fibers that make it they give it this drape so it hangs off you but then feels nice against the skin but it's also durable. Then we stumbled upon mycelium. When you looked at mycelium, it was this entangled set of micro scale routes and it suddenly became like okay, well that looks a lot more like leather, a cross section of leather than if you were to take our protein and try to make it into leather. We felt sufficiently confident that this was going to that mycelium, if we could make it into a large enough sheet would give you all the performance and it was a gamble, but the performance and the beauty and drape and aesthetic benefits and desirable characteristics that leather does. And so we started exploring it. And it became very clear that that was the way to go. And we had to really learn a lot more about filamentous fungi than we did before. Whereas we knew a little because filamentous fungi can also be a great protein producer, but we didn't know a ton in terms of using filamentous fungi to grow lots of mycelium versus to make lots of protein. So that was a whole new learning for us. And it worked.
As, as a founder, myself, I'm just curious, like, what were some of the darkest nights that you've had, so to speak, or you know, hurdles that you've had to go through? Maybe there's one day in particular that everything went to shit? Or you ran out of money? Or, you know what? I just curious to hear these kind of stories from people. Because so many people focus on the successes, but not a lot of people focus on you know, what, what did you have to go through to partner with like Adidas and make these amazing products?
How do I pick just one? Now I need to start with your final part to partner with Adidas, they've been they've been a phenomenal partner, we've, when we started this company, we said we're going to get into apparel, we thought the process would be as easy as making a sample, handing it to a brand, a brand would say this works for our product, we want to buy a lot of it or we want to invest in you. And we learned over time that there have been so little innovation in the material side and the supply chains were so established and commoditized and opaque that companies weren't even built anymore around being able to introduce innovation to the world, let alone innovation that scales in the way that biotechnology does, which is much lower volume and much higher costs initially. Then petrochemical based innovations. And so I got to give credit, though, through this whole process that we've been working with them. ATI has been working really hard not just to help deliver Mylo to the world but building it's its innovation arm to really not that's not innovation arm in the way they probably define it. But whatever, whatever engine they have internally to work with innovative materials they've been, they've been working hard. But the number of doors we've had closed on us slammed on us in the past have far outnumbers the conversations we had basically people saying, Oh, you know, we'll come back to us when you have tested this on 10 athletes over I don't know how many years, and you have it for cheaper than a barrel of oil, and it just completely on tenable. I mean, at one point, we were just like, there's no way we're going to be able to make this work. I mean, and from the perspective of sustainability, when we were first pitching the company in 2011, and we're just talking about micro silk, we said we're gonna have green because that was the term term of the art. And then we're gonna make green materials. We had one venture capitalists, they never talked to me about green. No one's ever gonna pay for green. You know, and here we are, people are working really hard and old data shows that consumers are really committed to investing in sustainable products. We have learned ways in which we have to compete on price and where we can compete on price ultimately, but sometimes it takes some some steps in scale before you get there.
Right. I'm I'm really excited to get those out of dodge shoes, myself and any other you know, myco wearables or anything. Yeah, I think I like that. myco wearables I'm I'm rooting for all the companies including bolt threads and incredible it's so needed in our world. We're growing at such an unsustainable rate, the human race and for a lot of our problems. fungi just have this holy grail shining light answer, you know, not for everything but, but can make huge leaps in the right direction. So thank you for what you're doing. I'm really really excited to see this blow up.
It's necessary. I wish we could go faster than we are. We are going at a breakneck pace faster than anybody is comfortable with but it's working, and, you know, there is a certain sense that you're racing against the clock, sort of a climate change clock. And we are just one small piece of that puzzle. But this is what we're good at doing. And we think it will have a very positive impact. So let's get into it in terms of what nature has evolved with fungi, you know, when we started bolt we were, we really, we started studying just not just spider silk proteins, but all proteins and it became, oh, look at all the cool things nature has evolved, the proteins can do, we can replace all sorts of materials with these bio based and biodegradable, like naturally evolved proteins. And then when we got into filamentous, fungi, it was the same learning, like you were just saying, but for a whole organism, like not just a metabolic product of the organism, but it was like, wait, look what this whole organism could do, not just what, look at what the protein it can make, but this whole organism can do it on its own. It's this phenomenal machine.
So I'm curious, just in comparison with both the silk and, you know, the the Milo of comparing it to its conventional counterpart on both the environmental side, and also the functional side, because a lot of times these super environmental, you know, solutions like like compostable materials, they, the sacrifice is in their function ability, right? They might fall apart a lot easier, or, you know, they might not hold up as well. So I'm curious if you want to give a comparison on both, you know, the hardiness, the functional ability of both the silk and the and the Mylo leather right now. And if there's any downsides that maybe you're working on, and then on the sustainable side of, you know, how much more sustainable are we talking about?
You know, we we put a ton of effort into ensuring with our partners parity on performance. And when I was talking before about audio, and this is true for other our other partners as well, Adi being very helpful and supportive. A lot of this was understanding what are the tests they do? What are the what are the tests for manufacturability? What are the tests for product performance? And where do we have to optimize and solve because we're trying to solve for the right problems and making sure that week, we don't make a material that might seem great, or, but then fails on aspects that would otherwise cause it to get adopted, it's been a lot of work to try to get to a point where we are not making sacrifices. Now, we're in a specific niche right now, which is apparel, I wouldn't say Mylo is yet ready to necessarily be. I wouldn't, I wouldn't drape my friends who ride motorcycles in it yet, because I I don't even know what goes into motorcycle gear. But I know if people's lives depended depend on it. So that's testing to be done in the future. But for now, in terms of apparel, we work really closely with these partners, and they give us a lot of insight onto what we have to what we have to hit to make sure that the product is functional, and they set a very high bar for us. It's motivating, it's hard. But we're we're hitting those goals. And the same ends up being true for sustainability. For all the concerns we have, we're had when we started that no one was interested in sustainability. Now we hold ourselves and our partners hold us to a very high bar on sustainability. And whereas it's easy for me to say how much more quickly my low gross than a cow and Okay, that's a that's a very simple approximation. To give you a top of the funnel idea of how you're probably going to be positively impacting the planet, you know, okay, you don't cut out the cow. You see, you're cutting out the methane, you're cutting up the land usage. The reality is, is the devil comes into the details, the end of life, what does it cost? Like? How long? How long is this product going to last? Where is it going to go when disposed? How many times it's going to be reused? How much energy does it take to make all all of these things come together into what's called a life cycle analysis. And there's tons of people working on these and we've made some pretty positive public declarations on how open we'll be with our lifecycle assessment and are working with partners. On our lifecycle assessment, it's hard to do that before you're in manufacturing scale, but it's the most accurate, mathematical and scientific way of keeping yourself honest as to, is this actually helping versus is this feel good? and marketing? Or is it only minimally helping? And how do we have to continue to optimize? You know, we, there's, there's great examples we have internally, I can't totally talk about in ways we need to optimize in terms of water uses that we've worked on and things like that, to make sure you're not making a sacrifice in some other area, that is the that without a full analysis the consumer would otherwise be blinded to, right wouldn't be transparent to the consumer.
Speaking of water, I'm just curious, because a lot of other myco materials, you know, I remember specifically a TED talk, I think it was Suzanne Lee, talking about kombucha clothing. And she was talking about how, you know, she's standing on stage and the bright lights, were making her sweat, and the water actually started to decompose the convention clothing. And it was that a hurdle that you had to jump through, because these are shoes, I'm guessing they'll be jumping in puddles and getting a lot more wet than then say, a jacket, so to speak. So is there you know, a special, I don't know how much absolute to it.
I can't speak to the solutions, but I can say, absolutely, um, for all of our products, particularly learning, learning how to the application requirements, the product requirements and apparel you learn quickly. For every mechanical test, or physical property tests, you can put wet in front of it. So strength, wet strength, and it is equally if not more important than the dry version. And so you're constantly constantly having to monitor those things. And you if it fails, in those tests, it can be a complete deal breaker, you really in that part of the challenge is biological materials tend to be on average, very water loving, very hydrophilic versus, say petroleum based materials that are naturally hydrophobic. So it definitely definitely takes some creative problem solving.
I'm sure everyone's got the burning question. When can we buy mylo adidas shoes?
Oh, yeah, it's Huck Finn. We all want to know, I think that's partly in our hands. So it's not totally up to our discretion, but they've said they'll be launching by the end of this year, publicly.
Sweet. I know, I'm rocking them.
Do you know how many shoes they're like, hoping to make?
I do not. I know that people within Bolton, though, and I know I'm not allowed to say.
That's so exciting. I feel like biomaterials get vindicated when there's like a giant commercial brand. That's stunting your materials. It's amazing to see that partnership as something as massive as Adidas that's global. That's just such a milestone for mycelium. As a textile. I'm so proud of you guys. I'm so proud of the industry. Yeah, it's good. Yeah.
When you think about the impact you can make, um, if you are in a race against time, in particular, which you also are as a venture capital back startup, in some ways, you need to work with and convince someone who has a global distribution, product development, distribution and marketing, established infrastructure to to utilize your material, otherwise, it's going to be very difficult to have a positive, positive sustainability goals in any reasonable amount of time.
So this is a question you definitely can't answer. But I'm going to try to think of a creative way to ask it still. I'm guessing you're working on other projects. And are you able to give a hint of what those are?
I'm able to give it what I can say I'd say is the nature has evolved a ton of fantastic organisms, a ton of fantastic materials and a ton of fantastic organisms that grow into interesting materials. And there's a huge opportunity to develop those into new materials for new products and that are that are more sustainable, sustainably made.
There's one last question we'd want to ask, we get a lot of people reading in just asking us how to experiment with myco materials. Do you have anything to say for this crowd of people are just at home and they want to play with mushrooms or fungi and try and make something viable? Y
ou know, I have I found the resources online to be incredibly valuable. I've shocking a shocking amount of instructions to just do stuff at home, whether you could just I mean, if you've done nothing, and you're just getting excited, just start by growing some mushrooms, which, you know, sounds trivial to experienced people. But if you've never done it before, it's astounding how quickly they grow. Just you know, you wake up one morning, you're like that didn't exist yesterday. And then I would say if you're interested in playing around and processing materials, not just growing, but if you actually want to take mycelium that you've grown or do something with it. Think about it this way. Cooking is a lot of chemistry and material science. You know, don't be afraid to you know, put put some mushrooms on the stove. And really, rather than just thinking about how they taste, how does it change shape? How does it How does it get absorbed moisture and oil? How can you shape it? How can you squeeze it? How do you get a shape to stay? All of that is material science, you're playing with fungal filaments hyphy. And basically do applying different conditions, chemistries and temperatures. You know, vinegars acidic, start playing around with that there's just so much you can do in your in your own kitchen that I think we forget. It's all very sciency. That's wonderful. I love it accessible to put it in the food processor and try to mash it back together.
And continue to be grateful that there's such a strong community out there and strong advocates for the space both in terms of mycology, and sustainable materials and biomaterials altogether. And all that we have a lot of fans for this journey because it's sort of a very iterative journey towards a better planet.
Big thanks to David Breslauer for giving us time to interview him as well as the whole team Apple threads and anyone actively in this revolutionary fungal materials industry.
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