WHAT puts the colour in your clothes? At present, the answer is usually petrochemical dyes. Now a French start-up called is offering a radically different approach: getting bacteria to make dyes in the lab, with sugars as the only raw material.
Thomas Landrain and his co-founders at Pili hatched the idea three years ago at a biohacking lab in Paris called . They wanted to build a pen powered by bacteria: feed in sugar, get back ink. Their first lead was a South American strain of Streptomyces bacteria which produces blue pigment. Landrain and his colleagues learned to extract the pigment and write with it.
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The group tried the bio-ink in an inkjet printer, and explored what it would take to use it with textiles. By fiddling with the microbes鈥� environment 鈥� feeding them different kinds of sugars, varying the temperature and the time 鈥� the team learned to control the ink production and even to coax Streptomyces and other bacteria into producing four other colours: red, yellow, orange and violet.
鈥淲e started to wonder if such a way of producing colours could become a true alternative for already existing petrochemical dyes,鈥� says Landrain.
Many inks are made from a mixture of petrochemicals and organic pigments; others involve compounds of heavy metals such as cadmium or lead. The black ink in a ballpoint pen, for example, gets its colour from carbon black, made by burning petroleum products. 鈥淲e began to imagine a future without that industry,鈥� says Landrain, one in which dye-making has no dependence on oil.
, who studies organic dyes and pigments at North Carolina State University in Raleigh, says it鈥檚 a fascinating idea. Modern dye production often relies on corrosive substances like nitric acid, something that synthetic biology could render unnecessary. 鈥淭he beauty of the bio approach is the elimination of harsh chemicals,鈥� he says.
鈥淪ynthetic biology is getting to the point where you can compete if you choose products carefully鈥�
at the University of California, Berkeley, agrees that it holds promise. 鈥淵ou see more and more companies exploring making commodity chemicals with synthetic biology, and I think it鈥檚 a really big step,鈥� he says. 鈥淭he technology is getting to the point where you can potentially compete if you鈥檙e careful about choosing your products.鈥�
In 2013, Johnson was part of a that genetically engineered E.coli bacteria to produce indigo, the dye used in blue jeans. Like Pili, Johnson鈥檚 team was looking for alternatives to synthetic dye, which is energy-intensive to make and relies on raw materials derived from oil. Johnson鈥檚 collaborator John Dueber is continuing the work, hoping to turn it into a commercial process.
Making a little dye in the lab is a neat trick; producing enough for industrial purposes would be a real feat. The denim industry gets through 40,000 tonnes of synthetic indigo annually. Scaling up bacterial production will mean understanding precisely what resources are needed to feed all the bacteria, and maximising the yield.
Pili is also testing how to get its bacterial dyes into clothes. Currently, the company grows the microbes right on the garments themselves. When dyeing is complete, the team kills the bacteria with heat or simply by throwing the clothes in the wash.
鈥淲hen you鈥檙e talking about replacing something made with petrochemicals, the production process has to be very efficient in order to compete with the scale and cost of current processes,鈥� says , a synthetic biologist in Cambridge, Massachusetts. Pili is working with the French pen manufacturer BIC to help answer some of these questions.
Bacteria鈥檚 colourful side has uses beyond industry. , a researcher and designer in London, has her own project to make patterned silk by growing pigment-producing bacteria on fabric. She wants to turn her technique into a craft, transforming her artistic vision into a series of scientific steps that anyone can apply.
Producing dye biologically is still in its infancy. But if it works, says Chieza, 鈥渢his could revolutionise how we dye in the fashion industry.鈥�
(Image: G.M.B. Akash/Panos)
This article appeared in print under the headline 鈥淭int without taint鈥�
