Indigo Dye from Genetically Engineered Bacteria

A study published in Nature Chemical Biology reports an environmentally friendly method of producing indigo dye from genetically engineered bacteria. Indigo is widely used to give denim its characteristic blue color, and this biological approach to its synthesis and application avoids the need for harsh chemicals.

Indigo is made naturally by certain plants and has been extracted for use as a blue dye for millennia. However, modern demand for the dye requires chemical synthesis at a large industrial scale. This process uses multiple hazardous chemicals, which can be harmful to the environment.

As a ‘green' approach to making indigo, John Dueber and colleagues used engineered bacteria that produce a related compound called indoxyl. Indoxyl itself is unstable, but the researchers identified an enzyme that can stabilize indoxyl by linking it to a sugar molecule. When added to bacteria, this enzyme produces indican, which can be easily isolated and kept for long-term storage. Later, at the time of dyeing, a different enzyme turns indican into the familiar indigo directly on the cloth.

For more, read the research highlight in Nature Asia.