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Worms produce pre-colored silk after eating dyed leaves

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December 5, 2013

Silkworms chowing down on one of their favorite foods – mulberry leaves  (Photo: Shutterst...

Silkworms chowing down on one of their favorite foods – mulberry leaves (Photo: Shutterstock)

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Like most other fabrics, silk is colored with dye. Unfortunately, the dyeing process results in wastewater laden with toxins. Now, however, scientists from the National Chemical Laboratory in India are developing an alternative. They're feeding dye to silkworms, which in turn are producing pre-colored silk fibers.

The researchers sprayed or dipped mulberry leaves in seven types of azo dye, which is the dye family most commonly used in the food and textiles industries. Those leaves were then fed to Bombyx mori silkworms.

Of the seven dyes, it was found that three ended up making their way into the worms' silk, causing it to take on the color of the dye. None of the dyes appeared to affect the worms' health.

Silkworms that consumed Direct Acid Fast Red azo dye produced these red fibers
Silkworms that consumed Direct Acid Fast Red azo dye produced these red fibers

This isn't the first time that silkworms have produced colored silk after eating dye, although the type of dye used in previous efforts was reportedly too expensive for commercial use. Azo dyes, by contrast, are relatively cheap.

A paper on the research was recently published in the journal ACS Sustainable Chemistry & Engineering.

Source: American Chemical Society

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
5 Comments

If "the type of dye used in previous efforts was reportedly too expensive for commercial use", somebody was not looking previous enough. I have a century-old sample of the fact that the same silkworms that produce white silk when fed on mulberry leaves produce beautiful golden thread from oak leaves -- easier to obtain than mulberry, which is why my mother used them.

The problem both new and old is control: if you want a particular gold (or green, or mauve, or ...), not just a colour in a particular ball-park, it will take a lot more experiment to get it than you need with a dye-vat.

Geometeer
6th December, 2013 @ 01:26 am PST

Okay - so perhaps a stupid question, but I have seen dyed flowers - so could you do the same with cotton - I am going to guess not without reverting to some clever gene splicing

myale
6th December, 2013 @ 08:24 am PST

I wonder about scalability. It is one thing to dip leaves in dye, quite another to dip a tree or bush.

Bruce H. Anderson
6th December, 2013 @ 12:15 pm PST

@Bruce H

You could probably inject it into the trunk, so it was taken up by the tree's water distribution system into the leaves.

For their next project they're working on a way to make cows give chocolate milk. :-)

Wombat56
6th December, 2013 @ 03:29 pm PST

Just checked Wikipedia and found problematic issues. These are excerpts from the article:

Many azo pigments are non-toxic, although some, such as dinitroaniline orange, ortho-nitroaniline orange, or pigment orange 1, 2, and 5 have been found to be mutagenic.[3] Likewise, several case studies have linked azo pigments with basal cell carcinoma.[4]

Azo dyes derived from benzidine are carcinogens; exposure to them has classically been associated with bladder cancer.[7] Accordingly, the production of benzidine azo dyes was discontinued in the 1980s "in the most important western industrialized countries".[8]

some aliphatic azo compounds are utilized as radical initiators. Because of their instability, aliphatic azo compounds pose the risk of explosion.

Certain azo dyes can break down under reductive conditions to release any of a group of defined aromatic amines. Consumer goods which contain listed aromatic amines originating from azo dyes were prohibited from manufacture and sale in European Union countries in September 2003.

dsiple
9th December, 2013 @ 02:54 pm PST
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