Spider silk, without the spiders
Two students set out to recreate spider silk. Nearly two decades later, fashion brands are wearing what they brewed.
Spider silk is one of nature's most remarkable materials: light, flexible and astonishingly tough. There is just one problem. You cannot farm spiders. They are territorial and tend to eat each other. Spiber spent nearly two decades finding a way around that.
Two students and the toughest thread
The story begins in 2004 at Keio University's campus in Tsuruoka, a small city surrounded by rice fields in Japan's Yamagata prefecture, home to one of the country's leading biotechnology institutes. Two students, Kazuhide Sekiyama and Junichi Sugahara, learned that spider silk was among the toughest materials known, and became obsessed with making it artificially.
In September 2007, they turned their research into a company and named it Spiber: spider plus fiber. The company is still based in Tsuruoka today.
Brewing a fibre
Since spiders could not be farmed, the only realistic route was to understand the proteins that make silk and produce them another way. Spiber's method, which it calls Brewed Protein, works like this. Scientists design a protein by choosing the sequence of amino acids that gives it the properties they want. They write the matching genetic instructions into microorganisms. The microbes are fed sugars from plants and fermented in large tanks, much like brewing beer. They produce the protein, which is purified, dried into a powder, and spun into fibre.
Along the way, Spiber realised it did not need to copy spider silk exactly. Once you can design proteins, you can make materials that feel like cashmere, wool, fur or leather, or that behave in ways no natural fibre does.
The idea started with spiders. The breakthrough was realising you did not need them at all.
The jacket that shrank
In 2015, Spiber revealed a prototype Moon Parka with Goldwin, the Japanese company behind The North Face in Japan. It was a sensation, and it had a problem. Real spider silk shrinks dramatically when it gets wet, and the early fibres did the same. Spiber spent more than four years redesigning the protein before the jacket was released commercially in 2019. It was a lesson in how long it takes to turn a laboratory breakthrough into something you can wear in the rain.
A $300 million bet
Making materials by fermentation at scale is extremely expensive, and Spiber has raised serious money to do it. In 2021 it raised ¥34.4 billion, about $312 million, led by the investment firm Carlyle, in what was reported as Carlyle's first growth investment in a Japanese startup. The deal valued Spiber at around ¥133 billion.
The money went into production. Spiber began mass production at a plant in Thailand in 2022, using sugar from local agriculture, and partnered with the American agricultural giant ADM on a facility in the United States that would use by-products from corn.
The strategy: a material platform, not a fashion brand
Spiber does not sell clothes. It sells materials to brands that do. Its fibres have appeared in outerwear and suits by Goldwin, a hoodie by the materials-focused brand Pangaia, couture by the Japanese designer Yuima Nakazato, and even car interior parts developed with a Toyota supplier. More recently, it has presented large collections of fabrics at Milano Unica, one of the most important textile fairs in Europe.
The strategy is to become a platform. Because each protein can be designed, Spiber can keep inventing new materials for new customers without inventing a new factory each time. It has also launched a programme with brand partners, which it calls biosphere circulation, focused on what happens to its materials at the end of their life.
What has to go right
For now, Brewed Protein is expensive and produced in limited volumes, so it tends to appear in premium pieces or blended with other fibres. Other companies making biomaterials, such as mushroom leather, have struggled to scale. Spiber's challenge is to bring its costs down far enough to compete with synthetic fibres like polyester, some of the cheapest materials on Earth, while keeping investors patient.
Why it matters
Most clothing today is made either from plastic-based synthetics or from resource-hungry crops and animals. Spiber offers a third route: materials designed on a computer and grown by microbes. It is a long, expensive bet that the future of fashion will be brewed.
Would you wear a jacket that was brewed?
