Scientists Engineer ‘Transgenic’ Silkworms to Spin Spider Silk
In what is being hailed as a breakthrough that could lead to the manufacture of stronger textiles for medical use, scientists have managed to genetically engineer silkworms that produce spider silk.
Dr Donald Jarvis, of the University of Wyoming in the United States, and colleagues created transgenic silkworms expressing spider gene sequences.
Spider silk proteins have been long produced in transgenic bacterial, yeast, plant, insect and mammalian cells. However, previous attempts to incorporate them into fibres spun by silkworms led to relatively low yields.
But the new technique, reported in Proceedings of the National Academy of Sciences, led to fibres at least as tough as spider silk and stronger than those spun by silkworms.
So silkworms may be used as factories for manufacturing tough silk fibres containing spider silk proteins, said the researchers.
Work toward producing mass quantities of spider silk has been going on for more than twenty-five years. Producing spider silk in industrial-scale quantities has benefits because, weight for weight, it is stronger than steel and as formidable as Kevlar.
Why not just farm silk from spiders, then? Well, this has proven practically impossible because spiders are both territorial and prone to cannibalism, meaning that they cannot be housed together in sufficient numbers to produce the necessary quantities to make the prospect viable.
As mentioned above synthetic spider silk genes have been placed in a number of hosts, perhaps most notably in goats. While the enhanced goats were able to produce limited quantities of the silk proteins in their milk they could not produce sufficient quantities for farming purposes.
However the more placid caterpillars of the silk moth Bombyx mori have already been farmed for a number of years so there is reason to think that their now enhanced silk could be produced in quantities that would allow for widespread harvesting.
Not only that, but it turns out that the transgenic silkworm may in fact be able to produce silk that is even stronger than would have been anticipated.
“On average, the composite fibres produced by our transgenic silkworm lines were significantly tougher than those produced by the parental animals and as tough as native dragline spider silk fibre. In best-case measurements, the composite fibre produced by one of our transgenic silkworms was even tougher than the native dragline spider silk fibre,” the scientists said.
Possible uses for the silk have already been identified in the medical field where it could be used as part of bio-materials for wound dressings, artificial ligaments, tissue scaffolds and more.
The wider engineering uses include improved bullet protection.