Decades of research have gone into the development of dyes made from fermentation. As biotech indigo, the signature colour of blue jeans, takes its first steps on the market, it could be paving the way for other, greener, biobased dyes. 

Disrupting an industry that produces some 70,000 tonnes of petrochemical indigo annually is no small feat. A handful of synthetic biology specialists claim to have already ticked key boxes: achieving purity levels comparable to conventional indigo and scaling production capacity — at least to a degree. The next step is to convince the denim industry to switch to these low impact alternatives.

Progress made by companies such as Pili, Chloris, Colorifix and Octarine Bio show that it is possible to offer dyeing solutions that require fewer chemicals, are processed at lower temperatures and release cleaner effluent. They are tackling one of the apparel industry’s most critical manufacturing stages. 

The new brewed indigos that have reached commercial scale at Chloris and Pili have been in the works for a decade or more. Chloris founder, Dr Lei Sun, has been working on a microbe-made blue dye for the past 13 years, since his PhD programme. “It took us ten years to increase yield from milligrams to kilogrammes, and beyond,” he tells Sportstextiles. The Utah-based company operates a factory in China, where 300-tonne bioreactors can produce 10,000 tonnes yearly. Dr Sun says that hundreds of tonnes have already been shipped to mills. “We are ready, and the mills are too, as soon as the brands say go.”

At Pili, based in France, research into biobased dyes began in 2015. Production of its first fermented dye, Eco-Indigo, began in 2024 and was shipped to its first customer, US premium denim brand Citizens of Humanity. Pili CEO and co-founder, Jérémie Blache, says that 100,000 units have been dyed. It marks a small, but significant, step towards industrial scale. The company intends to increase production in 2026, enough to dye a few hundred thousand items, and eyes one million Eco-Indigo-dyed jeans in the not-too-distant future.

The denim industry is a key focus for many companies developing biotech dyes. Its dependence on a single pigment, used to tint an estimated 1.5 billion jeans every year, is understandably an attractive prospect. It is driving research at Indian fermentation specialist Fermbox Bio, which has released a Synbio-Indigo in its portfolio, and at Danish company Nordic Blue, which is working on an “eco-friendly alternative for dyeing denim”. 

Beyond blue 

Another Danish company, Octarine Bio, has been releasing new shades in its PurePalette range, having started with pink, purple, dark green and blue. The company says its double expertise, in cell-factory engineering and in precision fermentation, has sped up time to market with the first commercial runs launched this year. Octarine Bio’s PurePalette dyes are made by microorganisms engineered to produce colourants that “bind directly on a fabric, or a fibre, without requiring heat, pressure, chemicals or mordants,” says Nethaji Gallage, co-founder and CEO. The company is now scaling up production and is working with several dye houses and manufacturers in Portugal. Its low impact dyes are being trialled by fashion brands and were featured in London-based Patrick McDowell’s spring-summer 2025 collection.

The novel biotech dyes developed by Colorifix, a UK company, also bind directly to a fabric in a process that takes place in fermenting-dyeing vats. In its process, specific strands of organisms are engineered to produce different shades. Portuguese textile and garment manufacturer Valérius has been operating one of Colorifix’s bioreactors for several years now. The biotech company is progressively expanding its network of licensees in Latin America and more recently in India and in Sri Lanka. This positive evolution is enabling it to move from small-scale industrial deployments to large-volume commercial capacity. “Over the last few years, we have gone from grammes to tonnes of fabric per week,” says company founder and CEO, Orr Yarkoni. This past June, the company successfully closed a new funding round of $18 million from Inter IKEA Group, H&M Group Ventures, the Goldwin Play Earth Fund and Youngone CVC.

Chloris’ first microbial dye, Claessen Blue, is made by an unmodified organism. Dr Sun’s interest was sparked by microbes that naturally generate a blue hue, first documented by German scientist H. Claessen in Berlin in the late 19th century. “He did fantastic work identifying a natural microorganism that produces the dye, and this allows our process to be highly efficient,” says the synthetic biologist who has been studying natural dyestuffs for 18 years. Pigments found in nature often pose challenges, he notes, as many are toxic and can damage the very cells producing them in fermentation tanks. By choosing a pigment produced by a natural, non-modified organism, he says that Chloris can achieve higher yields and offer a blue that is similar to indigo in shade and price. The company is looking to expand its palette; a brown shade has been launched, and a purple is in advanced trials. “We have 100 scientists looking for micro-organisms that can produce a pigment,” he says. 

Scaling capacity

Meeting the price point of conventional petrochemical dyes is a major challenge for these biotech companies. Indigo, for instance, is said to cost around $5 per kilogramme. Scaling production is thus the main pathway to lowering costs. Yet maintaining living cultures in tanks or reactors becomes increasingly complex at larger volumes, requiring sophisticated engineering to ensure stable temperature, even nutrient distribution, and consistent culture media. “There are ways to reduce costs through continuous culture, reusing media, or using alternative sugars instead of glucose. But these will not happen overnight,” says Efthimia Lioliou, founder of Synovance, a French company that was developing a biotech indigo, for jeans, and a red, for cosmetics. Despite positive trials and a small factory with a 1000-litre fermenter up and running, she had to shutter her business this autumn, when support from investors and industry failed to materialise.

“Scaling up is the most difficult stage,” agrees Dr Sun. “The fermentation process involves a series of complex parameters to control, including dissolved oxygen, temperature, and so on. Improper control can lead to abnormal microbial metabolism and even cell death.” He points out that all fermented materials face the same issues. Chloris feeds its microbes glucose derived from corn (~80%), which he says allows it to keep costs down. 

Up until now, Pili has outsourced the production of its pigment, but expects, one day, to have its own factory, and thus reduce costs. For now, it is working with a network of partners in Europe, and sourcing sugar exclusively from European biomass, says Mr Blache. The company has joined several research projects working on ‘second generation’ sugars derived from wood, paper, agro-industry waste and even textiles. “We would like to be the first company to use textile waste as feedstock, creating a truly circular solution,” he says. 

Making the switch

Dyeing is widely recognised as one of the most polluting stages in textile and apparel manufacturing. The advent of biobased colourants with a radically lower environmental footprint compared to petrochemical dyestuffs should incite change. While cost remains a critical factor in a price-sensitive apparel market, it raises the question: What proportion of a product’s total price does dye actually represent?

In discussions with brands and mills, Jérémie Blache, at Pili, says many different reasons are cited as potentially triggering change. Responsibility, which encompasses sustainability, and a desire to implement best practices, are among these. “We are creating a new standard that is reliable,” he says. Traceability is an issue that luxury brands tend to focus on. Innovation is another draw that he cites. Keeping ahead of future laws and regulations “can be strategic for a brand”. He believes that extended producer responsibility and environmental scores will, at some point, “level the playing field by making it more expensive for less sustainable companies to do business”. 

Differentiation is another key motivator for adoption. “Brands have few ways to differentiate in a bold and convincing manner, beyond style and price, and biotech indigo is one such strong differentiation point. It is also a fairly easy notion to understand for consumers,” he adds. 

The tipping point for dye houses and brands is sustainability and safety, says Dr Sun. “The wastewater discharged from our factory contains no organic solvents, no heavy metals, no aniline, just small amounts of sugars, amino acids and inorganic nitrogen sources. It can even be used as fertiliser.” 

Dr Sun has spent years learning about dyeing, and says that Claessen Blue presents several advantages: a lower working pH, requiring less supplementary salts, and a lower oxidation-reduction potential (ORP), a measure used to monitor water quality. In the energy- and chemical-intensive laundry stages of jeans-making, it is processed at lower temperatures, which helps preserve the elastane content. 

Chloris Biochem thus promises dye houses convenience and savings. “Mills are motivated to switch because of the savings on resources, chemicals and even wastewater treatment costs,” says Dr Sun. They do, however, need to be persuaded to switch from a pigment they know well to a dye they have no experience with. It is a new molecule, which means new recipes need to be devised. “We are the ingredient, not the chef,” he says. “We need the dye technicians to achieve the best results.” 

While convincing brands is not an easy task, Dr Sun insists on the positive story they can tell by using a biobased dye that biodegrades into amino acids, while offering savings in dyeing and laundry processes. “This is our most important contribution. We are not expensive and could even be cheaper than synthetic indigo,” he says. 

Dye houses have been reaching out to Pili, says Pierre-Yves Bollé, Pili’s chief business officer, looking for innovation and differentiation. If Citizens of Humanity was keen to adopt the novel biotech dye, it is due in part to the company’s in-house manufacturing. “It would be good to see brands that are truly dedicated to better practices benefit from the added effort they put into making their products.”

As with many next-gen materials and dyes, the industry is slow to switch to solutions that address one of the most glaring issues in textile and apparel manufacturing. There are, however, signs of change as early movers adopt low-impact dyes for commercial ranges, as seen at Citizens of Humanity, and at Levi’s, which has adopted Nature Coatings’ BioBlack, a pigment derived from wood waste. While these alternatives may carry a small additional cost, their environmental benefits, along with the positive impact on the industry’s image, could be far-reaching. 

Chloris’ biotech blue pigment is made by a natural, not a genetically modified, microorganism. 
Credit: Chloris Biochem

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