Researchers continue path toward commercialization of spider silk drawn from transgenic goat milk
By Tim Kalinowski
Spiders are known for two things: Creeping people out, and producing beautiful, high-tensile webs in an effortless way— webs which are simultaneously captivating in their design and deadly efficient at ensnaring and trapping prey in bonds which they cannot escape.
What if you could have spider silk’s amazing qualities, but substitute cute little goats as the producers of these amazing fibres?
That’s just what researchers from the Department of Biology at Utah State University have done.
“These goats were genetically engineered to produce spider silk protein in their milk,” explains Justin Jones, the university’s project leader for the goat spider silk project. “So they are only different from normal goats in one critical way in that they produce on extra protein in their milk. It represents a fairly unique way to produce these recombinant spider silk proteins at relatively large amounts of the protein.”
Jones has two students in his project who work with the goats 24/7 to maintain bio-security, care for the animal’s needs, and tend to the ever-important milking.
“Once they have collected the milk, we bring it back to the laboratory,” he says. “We use a common technique called tangental flow filtration, which is just really kind of molecular sieve, to purify away the fat and some of the milk protein to really enrich what we call the concentrated clarified way that has our spider silk in it.”
The protein is then subjected to ammonium sulphate treatment to separate the spider silk proteins out for collection.
“It comes out in a powder form,” explains Jones. “Goats obviously can’t spin fibre or produce anything more than just the protein. Once we have it isolated from the goats, then we have to do something with it. We then take them to fibre development or films, or coatings, or adhesives, and do these fun other applications we can do with them.”
Jones goat spider silk project currently has about 65 animals.
“We do a natural breeding program where we’ve got some transgenic billy goats we breed to non-transgenic goats,” he explains. “We’ve also got transgenic does that we breed to normal billy goats to produce offspring. About 25 per cent of our female offspring are transgenic and carry the spider silk gene, and about 50 per cent of the billy goats will be transgenic.
“Every kid that is born in my facility,” Jones adds, “we draw a little bit of blood from and we perform PCR (Polymerase Chain Reaction) testing to validate whether or not they do have that spider silk gene present.”
Jones says the next step for the program is to open up some commercial market opportunities for the goat-made spider silk.
“I think we are certainly closer than we have ever been to commercial marketability,” he states. “We are probably three or four years away from having the production capacity to be able to have spider silk satisfy a niche in a market … There is still no product out there made from spider silk that utilizes the core characteristics of spider silk, and that’s its strength and elasticity.”
He foresees a future where he may be able to help establish and licence breeding herds with commercial farmers, but he acknowledges there are also complexities in attempting to do so.
“I think there is the possibility for that in the future, but the one real hang up right now is we are pretty heavily regulated by the FDA and the USDA because these are genetically modified organisms,” he explains. “We have to keep them behind double fencing, and track the animals very closely so nothing of them enters the food supply.”
But still, Jones remains optimistic his goats may one day find greater commercial market acceptance; albeit on a limited scale.
“I think we are quickly approaching the point where products are becoming a possibility,” he states. “Coming from a goat herd, you can’t produce metric tonnes of material. It is just too cost-sensitive to be able to do that. I think kind of where we’re headed is identifying some niche markets that would be small value-type markets, but high-value products.”