Researchers of South Korea have developed a sustainable technique to produce large-scale indigo dye from microorganisms without the use of toxic chemicals.

Researchers at the Korea Advanced Institute of Science and Technology (KAIST) in the city of Daejeon were able to metabolically design corynebacterium glutamicum by injecting DNA, a kind of bacteria, to generate indigoidine, a natural blue dye that is more sustainable than traditional indigo.

Their study was published in the peer-reviewed ACS Sustainable Chemistry & Engineering journal that determined that the dye had the potential to replace indigo after testing it on white cotton textiles.

This is a cautious gain for the denim industry, which is always looking for more ecological dyeing techniques. Despite the fact that indigo dye was initially derived from the indigo plant, most indigo pigment is now chemically produced and is not water-soluble. 

To dissolve, sodium hydrosulphite, a caustic salt that eventually ends up in the world's rivers, must undergo a chemical process known as reduction.

This is especially concerning when you consider that 70,000 metric tonnes of indigo are used for denim items each year, according to DyStar, a German chemical supplier. The Cadira Denim System, which replaces hydrosulphite with an organic reducing agent, Sera Con C-RDA, and combines it with DyStar Indigo Vat 40 percent Solution to make the “cleanest indigo on the market,” tackles this issue.

Others, such as Archroma, the producer of Denisol Indigo Pure Indigo 30, and Sedo Manufacturing, the creators of Smart Indigo, have turned their attention to indigo powder to reduce its environmental impact.