Worms with spider genes spin silk tougher than bulletproof Kevlar

October 11, 2023

Katherine Bourzac, Science.org, September 20, 2023

Milestone advance in silkworms could lead to commercial applications in medicine and textiles

Spider silk is stretchy, strong, and tough. But genetically engineering a more cooperative organism to produce it has proved elusive. Now, researchers have used gene editing to make silkworms that can spin spider fibers tougher than the Kevlar used in bulletproof vests.

The material, described today in Matter, is “a really high-performance fiber,” says Justin Jones, a biologist who engineers spider silks at Utah State University but who was not involved with the research. It could be used to make lightweight but tough structural materials for fuel-efficient planes and cars, he says, wound dressings for faster healing, and superthin but tough sutures for eye surgeries.

People have been cultivating silkworms for thousands of years, unwinding their cocoons to provide material for textiles. But their silk breaks easily. Spiders have the opposite problem: They make incredible silks, but the arachnids are hard to cultivate. One hundred silkworms can hang around peaceably in a small space, whereas 100 confined spiders will attack one another, until only one or two are left alive.

In an attempt to harness the best of both animals, researchers have tried for years to genetically engineer silkworms to make spider fibers. But spider silk proteins are large, and the correspondingly large genes have been difficult to insert in the genomes of other animals.

So in the new study, Junpeng Mi, a biotechnologist at Donghua University, and colleagues chose to work with a relatively small spider silk protein. Called MiSp, it’s found in Araneus ventricosus, an orb-weaving spider found in East Asia. The scientists used CRISPR to insert MiSp in place of the gene in silkworms that codes for their primary silk protein. But the scientists retained some silkworm sequences in their MiSp gene construct, Mi says, in order to ensure the worm’s internal machinery could still work with the spider protein.

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