Synthetic spider silk for you.
Happy Halloween! Microbial silk's players, applications, and impact.
This is the first installment of Fifth Industrial, a newsletter diving into emerging biotechnology applications in food and materials that will enable a multi-planetary, post-animal, and decarbonized bioeconomy built on the principles of industrial ecology.
If you made a list of the most magical materials in nature, I’m confident that spider silk would be on it. Spider silk has captured the public imagination (see Spiderman), enchanted engineers with its tensile strength five times that of steel, and has booby-trapped the path of any woodland forager.
The mystique and ubiquity of spider silk are probably why it was one of the first naturally-occurring materials that garnered significant scientific and commercial resources to biomimic at an industrial scale.
Over the past 15 years, ten companies have formed to produce spider silk through various mechanisms (primarily cellular agriculture). Their applications in textiles, defense, medicine, cultivated meat, cosmetics, and more clearly have the potential to transform entire economic sectors.
The next four sections will provide a primer on the technology, a snapshot of the companies in the space, an overview of applications for spider silk, and lastly implications for the future.
Spiders, silkworms, and a few other arthropods produce silk, a protein fiber. Spider silk in particular is sought after due to its superior strength, elasticity, and (perhaps) coolness factor. Spiders produce several kinds of silk: one specialized for protecting eggs, a sticky kind for capturing prey, and the flagship structural silk that is used for dragline support and is the aim of much research. Various glands in the spider abdomen contain proteins that are combined in the organism to produce silk that solidifies as needed via an acidification process in the gland (see image above).
Spiders are a nightmare to farm due to their territorial and cannibalistic tendencies. Also, can you imagine a large scale spider farm? Nope, no thanks. We want the silk, so the solution is to produce the silk proteins without the spider or its glands — just like how Eli Lily used yeast to produce human insulin without pigs or their pancreases for the first time in the 1980s.
Bolt Threads: From genetically modified yeast. Also making mycelium leather. Berkeley, California. Founded in 2009.
Spiber: From genetically modified e. coli. Tsuruoka, Japan. Founded in 2007.
Spiber Technologies. Via recombinant methods (host strain unclear). Not related to Spiber in Japan. Stockholm, Sweden. Founded in 2008.
AMSilk: From genetically modified e. coli. Recently sold cosmetics arms to Givaudan. Munich, Germany. Founded in 2008.
Seevix Material Sciences. Spider silk proteins via recombinant methods (host strain unclear). Jerusalem, Israel. Founded in 2014.
Inspidere. Spider silk protein from the milk of genetically modified goats. Eindhoven, Netherlands. Founded in 2015.
Kraig Biocraft Laboratories: From transgenic (genetically modified) silkworms (b. mori), which they claim has a lower production cost per kg than fermentation. Ann Arbor, Michigan. Founded in 2006.
Spidey Tek: Spider silk fibers produced via plant molecular farming of alfalfa (from what I can tell). Los Angeles, California. Founded in 2015.
Spider Silk Research Lab: Silk from 3+ spider species via recombinant methods (host strain unclear). Founded in 2018. Kensington, Australia. Founded in 2018.
Spintex: Silk with a focus on fiber spinning technology. Production platform unclear, but uses liquid silk proteins. Oxford, England. Founded in 2018.
Dr. Randy Lewis: Pioneering researcher in the field. Faculty member at U Wyoming Dept of Molecular Biology. Has been at this since the 1990s.
As with many industrial biotechnologies, production costs remain a barrier to commercialization except for high-value applications. This leads to most companies focusing on low-volume, highly functional applications (e.g. medical devices) while they scale up production and reach a marginal cost where additional applications make sense (e.g. furniture). This is famously the “Telsa model” — start with expensive sportscars until you can sell affordable sedans, but we’ve also seen it with the biotech-enabled Impossible Burger launching in fancy foodservice (Momofuku) before reaching retail in 2020.
Soluble spider silk proteins are largely produced via cellular agriculture (like beer fermentation) and the resulting protein-label liquid can be used in gels, foams, coatings, ingredients, or “spun” into the classic strands. Companies are selling these proteins almost exclusively B2B under fun brands like “Biosteel,” “BioSilk,” “Dragon Silk.”
Here are some of the applications that have emerged so far or seem likely to emerge:
Textile and metals innovation plunged us into the First Industrial Revolution, so it’s fitting that textiles stronger than metal will bring us into the next. Some of the first commercial applications for spider silk are expensive clothes in partnership with big brands like Stella McCartney (Bolt Threads), North Face (Spiber, above), ASICS (Seevix). Of course, textiles also have applications in medicine, sports/outdoor gear, uniforms, construction, filtration, and much more.
Seemingly the most common application area is medicine because silk is supposedly non-reactive and anti-microbial (plus the margins are good and it’s subsidized). Uses include surgical meshes, wound dressings, tendon/ligament repair, and biofilms on implantables.
Multiple companies are pursuing the big money that comes with defense applications (particularly in the USA). Bulletproof armor is a vivid example, and specialized silk can be lighter and more flexible than Kevlar. Inspidere even developed a “Bulletproof Skin” (that partially stopped a .22 caliber shot) by culturing human skin on a spider silk scaffold. I’m guessing the U.S. DoD’s DARPA was intrigued. In 2018, the U.S. Navy funded a grant to explore using spider silk blasters to disable enemy ships.
Regenerative Medicine/Cultivated Meat
Cultivated meat (also known as cell-cultured meat), producing animal cells outside of the animal in a bioreactor, is poised to transform the way meat is produced. It is based on advancements in biomedical tissue and organ engineering. Spider silk companies are working on both, particularly the challenge of providing 3D structure through scaffolding or spheroid development. In September 2020, Seevix joined an Israeli consortium working on cultivated meat alongside Aleph Farms and SuperMeat.
Other: Cosmetics, Aerospace, Materials
I’ve seen many applications in cosmetics (throwing spider silk in shampoos, face creams, etc). Additionally, specialty silk has aptitude in aerospace due to its strength and lightness— Spidey Tek has even prototyped a drone made of it. The unanticipated applications in material science could very well be the most prominent or numerous. Some include adhesives, chemical sensors, fiber optics, belts/fasteners nanomembranes, coatings, and polymers (like plastics).
I’m surprised there aren’t more companies applying spider silk given its unparalleled functionality and compelling narrative of where it comes from and how it will change the world.
The most common textile is polyester, which is produced from coal and petroleum in a carbon-emitting process. More than 70 million barrels of oil are using in polyester production annually that could be replaced.
Removal of Animals from Supply Chain
Spider silk can be a replacement for the ~$20 billion traditional silk market, which relies on the inherent killing of over 6,000 silkworms per kg of silk (the silk is from their cocoons).
Industrial Ecology: Water Use
Natural systems don’t waste water or materials, they are almost immediately recycled. Silk is the most water-intensive fabric — significantly worse than cotton — using 1,000 tons of silk per 1 ton of silk produced. Additionally, spider silk is highly biodegradable compared to many of the petro-materials it replaces.
I’ll end by predicting that spider silk fermentation will play an important role in establishing interplanetary civilization, like a Mars base. Even more so than the lightweight rocketry equipment it could create, fabrication with spider silk could become the biopolymer on which many off-planet industries are built. The key is the fungibility/versatility of the protein. Rather than building oil refineries, diverse agricultural supply chains, and machining equipment, we could use a single fermentation supply chain (with the microbes’ feedstock as glucose or maybe even CO2). We can then use those silk proteins to spin durable textiles (I doubt fast fashion will exist in space), 3D print medical devices, or produce whatever lightweight structural materials or coatings we need to create new worlds in resource-scarce environments.
Happy Halloween and thanks for reading!
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Edit: I had missed Spintex from the competitive landscape so I’ve now added them.