Indigo Dyeing / Bio-Pigments Interview

Collection: Sea Change

Denim Dyeing Set for Disruption by Synovance's Bio-Produced Pigments

Almost nothing has changed in the production of indigo for over a century. But now, French biotech innovator Synovance is producing dyes from microorganisms using industrial waste as raw material. Co-Founder and COO Efi Lioliou explains how the company has been able to produce sustainable dyes using biochemical methods.

Subir Ghosh

8 April 2024

6 minutes

Long Story, Cut Short

The process is similar to beer fermentation except that the final product is pigment.
The process is sustainable because not only it eliminates the use of aniline & other toxic chemicals that are used during the synthesis of indigo, but also emits >10X less CO2 than the chemical synthesis.
The plan is to scale renewable sugar sources as feedstock.

Pigments of Disruption Synovance's bio-produced pigments are pure molecules (GMO-free) that are identical to the synthetic ones. They offer a “plug and play” solution: they replace directly the chemical equivalents, and there is therefore no change in the process of dyeing required. Synovance

texfash.com: There's a lot of work being done when it comes to bio-based colour/ pigments. About bioproduction your website says that the "microorganisms ferment sugars and salts and convert them to dyes". Could you explain this in a layman's language? How does the whole thing work?
Efi Lioliou: Our process is similar to beer fermentation except that the final product is pigment. We feed the microorganisms with sugars and it converts them to pigment(s). It is a simple carbon-to-carbon conversion (C-to-C). Our microorganism can do this conversion because we have incorporated into its DNA some foreign genes from another species that will produce the enzymes that are necessary to direct the carbon flow from sugars into the pigment, and in particular indigo. After our microorganism grows and reproduces into our fermentation tanks, we collect the biomass (cells with indigo), remove the culture medium and obtain pure indigo after our Downstream Process (DSP).

Again, the website says: "...purified using biochemical methods". How planet-friendly are these chemicals?
Efi Lioliou: We do not use chemicals in our DSP. We use a biophysical method for lysing the cells based on application of high-pressure (cell homogenisation). This is followed by sequential steps of centrifugation, water washing and drying.

This is related to the earlier questions. How is it a "cradle-to-cradle" and sustainable solution? Could you please elaborate, especially where your responsibility ends and someone else's begins?
Efi Lioliou: Our process is sustainable because not only it eliminates the use of aniline (classified as human carcinogen) and several other toxic chemicals (e.g. hydrogen cyanide) that are used during the synthesis of indigo, but also emits >10X less CO2 than the chemical synthesis. A predicted >170,000 tonnes of CO2 will be avoided in 2028 based on our current production estimates. If the whole synthetic indigo market were to be replaced by bioproduced indigo we could save up to 3 million tonnes of CO2. And this is only for one colour.

What’s more—we are currently testing alternative methods of indigo reduction to avoid the use of the traditional chemicals (hydrosulfite) that are used in the industry.

Our solution is cradle-to-cradle because we use as feedstock in our fermentations sustainable sugars (by-products of the sugar industry as well as lignocellulosic waste and potato peels waste) through application of proprietary technology. In this way we valorise streams that normally go to waste.

A bio-based economy that uses plant-derived resources needs land to grow them, in the first place. Where and how are the plants that you need are grown? Again, a planet-based resource base would be vulnerable to climate change. Your comments, please.
Efi Lioliou: As stated previously, we plan to scale renewable sugar sources as our feedstock. This is not only environment-friendly as we use a waste stream, but also beneficial to our costs and pricing. We do not use plants and we do not compete with food resources either as we do not use sugar.

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Next is the issue of volumes. Could you tell us how many acres/hectares of land is needed to grow the plants that would be required for dyeing X tones of, say, cotton fibres? Or, say, to dye 1000 t-shirts?
Efi Lioliou: Having clarified that we use waste streams and not crops of plants, here are some calculations and also a comparison with plant derived indigo.

The cotton yield/acre (in pounds) for US in 2023 was 845 pounds = 380kg (Statista).
According to Fibershed, 11.88kg of pure indigo (or 30kg of 40% purity pigment) can be extracted from 1 acre and this is sufficient to dye approximately 280kg of cotton.
If we assume an average of 280g of cotton used per t-shirt, cotton from 1 acre would be sufficient to make 1,357 t-shirts or 0.73 acres for 1,000 t-shirts. Then this would need 1 acre of pure (100%) indigo plant crops (at 12g of dye/t-shirt) or 2.5 acres of 40% indigo crops.

For our estimated 1,000 tonnes production of indigo in 2027, we would need 16,750 tonnes of molasses (taking into account a 40% sugar content). This would mean 200g of molasses to give 12g of indigo (estimate to dye a t-shirt). As molasses represents 4% w/w of sugarcane we would need 5kg of sugarcane,*but*this is the part of sugarcane not used for sugar production, it is waste that we valorise.

How is the derived pigment applied or used across the various industries, specially textiles? Is it DIY for your clients, or so you have to do some kind of hand-holding?
Efi Lioliou: Our pigment (indigo at a first point) replaces directly the synthetic dye. There is no need whatsoever for change in the manufacturers’ production. It is a drop-in product. This applies both to textiles and cosmetics. A small adjustment in the quantity of dye added in the dye bath may have to be done to meet purity of the synthetic indigo as today we are not at >95% w/w. However, our purity is far superior to that of the plant derived indigo (max. 40%) used by the industry and small scale pilot tests have shown that we can achieve purities greater than 90%w/w still using only biophysical methods.

You are coming up with a number of colour shades. How is that possible? What is the limit that you can stretch things to?
Efi Lioliou: If a biological pathway for production of a certain colour is identified then we can introduce it into our microorganisms. Even if the pathway is not studied but we know that a certain microorganism produces a certain colour, we can define the genes necessary for colour production, although this would take more time. The only limit is how well our microorganisms will tolerate the new “load,” what yield we can optimally achieve and if this is financially meaningful.

Indigo paste made at Synovance. The startup is focused on replacing the toxic synthetic dyes that damage the environment with bio-produced eco-friendly ones. Synovance

Please take us back to how you arrived at the various formulae for the different colour shades? How long did it take from idea to implementation?
Efi Lioliou: We explored different identified colour biosynthetic pathways and we implemented them into our strain. The first bacterial chassis we made took almost a year of work. After that a lot of “genetic parts” were reused for following colours. Now, the time we need to make a strain from design to validation is approximately three months. Depending on the complexity of the pathway, this may vary a little bit. However, please bear in mind that after a strain is made, we can keep working on it to further improve the yield. It is like having a prototype that you need to further improve.

A new idea/product does not always catch the fancy of people. Who were your first clients and how easy or difficult was it to convince them to use your products?
Efi Lioliou: Please believe me when I say that it was never difficult to convince brands (or manufacturers) from textile or cosmetics industries to use our products. Of course, people want to test the performance of a new alternative. However, people are looking for natural alternatives to replace the chemical ones to eliminate dependency on petrochemicals but also to avoid potential toxicity risks. Today, I cannot name people that we are working with, other than our partner Luigi Caccia, founder of PureDenim mill in Italy. Luigi was truly the first adopter to embrace our work and we are thankful for his continuous support.

Colours, dyes, pigments, chemicals. How do you see the market develop in the next few years? Are textile/fabric manufacturers keen on going the bio-economy way?
Efi Lioliou: Related also to my previous response, brands and manufacturers are keen on going the bio-economy way. Other than the environmental/societal related reasons there is a regulatory framework in place, especially in the EU, for production of sustainable textiles. There are regulations in place or envisaged to be implemented soon as well as world-wide voluntary standards that will force brands into sustainable solutions.

Traceability and eco-labels will not allow brands to use components (dyes) that are not environmental friendly and have consequences for the people working in the industry and the final customers. So, brands will have to comply. Also, by using eco-friendly ingredients they have a strong marketing advantage.

Last but not least, their willingness to adopt our products will strongly depend on the price competitiveness of our solution. And here is the best part: our solution will be competitive in the next 3–4 years time. So for the first time, it is possible to disrupt the industry.

Efi Lioliou

Co-Founder and COO

Synovance

If a biological pathway for production of a certain colour is identified then we can introduce it into our microorganism. Even if the pathway is not studied but we know that a certain microorganism produces a certain colour we can define the genes necessary for colour production, although this would take more time.

Subir Ghosh

SUBIR GHOSH is a Kolkata-based independent journalist-writer-researcher who writes about environment, corruption, crony capitalism, conflict, wildlife, and cinema. He is the author of two books, and has co-authored two more with others. He writes, edits, reports and designs. He is also a professionally trained and qualified photographer.

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