Using bacteria to dissolve indigo for dyeing

Indigo has been one of humankind’s favourite dyes since prehistoric times, and remains today one of the most important textile dyes, largely due to the enduring popularity of denim jeans. Indigo is insoluble in water, and to be used as a dye it has to be chemically reduced to a soluble, colourless chemical form, which is called indigo white. For the past hundred years the dyeing industry has relied on the reducing power of alkaline sodium dithionite, (also known as sodium hydrosulphite) but this results in large quantities of sulphur waste to be disposed of. Before the introduction of chemical methods, indigo was dissolved in a fermentation vat, where anaerobic bacteria reduced the indigo. This method is still used on a small scale commercially in India. Harnessing the power of bacteria to dissolve indigo industry-wide would help lessen the environmental impact of producing blue jeans.