Green jeans

Why are jeans blue? Because they’re dyed with indigo. This dye used to be made of plants. For more than a century now, it’s been synthesised from petroleum, a process that produces lots of nasty waste. Biochemist Marco Fraaije (University of Groningen) used E. coli bacteria to make indigo.

Jeans (already blue back then) were patented in 1873.

He equipped these intestinal bacteria with an enzyme from another bacteria, the Methylophaga (which can be found in the sea). If you put the souped-up E. colis in a reactor vessel with water, sugar and some other nutrients, then the following day the entire vessel will be indigo-blue. That’s great, but Fraaije is thinking ahead.

‘We’re trying to ensure that this process is applied in the most practical way possible in textile factories,’ he says. ‘It could become cheaper than the present production method for indigo. You can attach an eco-label to it as well. That’s an interesting option for the clothing industry.’

Read more in ExperimentNL

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