Genetic Engineering: ‘Spider Goats’ Create One of the Strongest Known Substances

Geoffrey Fattah
Deseret News
July 8, 2011

Utah State University professor Randy Lewis’s goats look and behave like most other goats: They nibble on alfalfa and, if you’re not careful, they might nibble on your clothes. But these goats could hold the key to revolutionizing everything from tendon replacements and stronger parachutes to safer airbags.

How can these goats achieve such amazing things? Lets just say, they have a little bit in common with comic book legend Peter Parker.

Lewis’s goats are transgenic, meaning they have two key genes that allow a spider to weave their silk inserted into their genetic code. The result is goats that produce milk that contain spider silk proteins.

Nicknamed “spider man” by his fellow USU scientists, Lewis’ first-of-its-kind research has gained him international attention. His work has been featured in top science journals as well as National Geographic and Time magazines. He was also featured on PBS’s NOVA and the Discovery Channel. He has been featured on European television and more recently in Canada.

Lewis recently brought his research from the University of Wyoming after USU lured him with better facilities and funding. The university was able to recruit Lewis through the USTAR program: the Utah Science Technology and Research Initiative. USTAR is a long-term, state-funded program that invests in science research with innovation and commercial potential.

Researchers and biochemical companies have long thought spider silk to be an ideal material for countless applications. It’s stronger than steel and as stretchy as nylon. But milking and caring for them is much easier than working with spiders.

“They’re territorial and cannibalistic,” Lewis said. “Scientists have known since the late 1800s that farming spiders isn’t possible — spiders tend to eat other spiders.”

It took about 80 people four years to harvest enough spider silk to weave a half-million-dollar golden tapestry. The 11-by-4-foot tapestry was displayed at the New York Museum of Natural History in 2009. Made by artists in Madagascar, the threads were harvested from over a million spiders, according to the museum. The tapestry is only one of two spider silk textiles known in the world.

While amazing, harvesting silk from spiders by hand is simply not commercially viable. Lewis has experimented with inserting spider silk genes in E.coli bacteria, alfalfa and silk worms. Lewis said bacteria can produce silk a lot faster but because of their tiny size, they don’t produce as much. Silk worms produce silk that is only partially spider silk and is not as strong. So he settled on goats.

“It takes goats six months to mature. In six months they have babies and you’re getting milk,” he said. “Also, they’re pretty docile, they certainly become acclimated to humans very rapidly.”

Initially Lewis teamed up with a Canadian company that produced the first goats. “We provided the genes and they provided the tech to put it in the goat.” Unfortunately, the company went under and Lewis’s team was stuck with a problem. “We made two very long trips to Canada to bring them back down. First to Wyoming and then here to Logan.”

Currently the herd of special goats is at about 36.

USU officials say they are excited to have such a renowned scientist bring his work to a Utah university.

“We are pleased Randy has joined the USTAR facility,” said Robert Behunin, vice president for Commercialization and Regional Development. He said that the core of USU faculty specializing in science and engineering and the new USTAR BioInnovations Center will provide Lewis with great support. “The commercial applications of Randy’s research are far-reaching and have enormous potential,” Behunin said.

Lewis has managed to gain $3.2 million in research grants and was recently awarded another $40,000 from the state in a Technology Commercialization and Innovation Program grant. His technology has also gained the interest of the National Institutes of Health, the U.S. Air Force, Department of Energy, National Science Foundation and U.S. Department of Agriculture.

Silk from milk

Lewis’s goats are milked about twice a day; however, there are a lot of other components from the milk that need to be removed in order to isolate the two key proteins that make spider silk. The goats are separated into two groups, each group contains one of the two proteins to make the silk, so the proteins must be extracted and then combined.

The milk is frozen and the cream is separated, which removes most of the fat but not all of it. The thawed milk is then pushed into a micro filter that blocks the larger fat molecules and lets the smaller proteins through. A smaller, more refined, filter then further isolates the silk proteins. “When we dry it, it looks like a white powder,” Lewis said. Still, the challenge remains: how do they take a powder and spin it into a fiber, like a spider does?

Spinning silk into gold

“We’ve been able to somewhat duplicate that,” Lewis said, but for now spiders remain the masters. On average, spiders can spin six different types of fibers with various properties. Lewis’ team has managed to spin a fiber similar to a spider’s suspension line, which is the thicker of the fiber types.

The two proteins are combined into a solution and pushed into a needle, but a spider pulls the silk out of its spinners, where a syringe would push it out. So lab workers tease the silk out of the needle and then pull it out like a spider. “They pull it out like floss, not push it out like toothpaste,” Lewis said.

What they get is a fiber that is incredibly strong, amazingly light-weight and very versatile. In current medicine, doctors takes a torn ligament or tendon and carefully sew it together, providing a less-than-durable treatment. Lewis said silk is very compatible with the human body and can be used as temporary tendons and ligaments while providing a scaffolding for the body to begin healing the tear together. “Right now there’s nothing out there that can do that,” he said. Silk can also be used to suture damaged eyes, or even nerves.

The military is interested in spider silk to manufacture better parachutes and cables, providing much more strength for the same amount of weight of current materials. Even auto manufacturers are interested in silk to provide safer air bags. Lewis said one feature of spider silk is that it absorbs energy better. Current air bags can knock children and adults back into their seats when deployed, causing possible injury. Lewis said studies show spider silk appears to better absorb energy and would minimize such knock-back.

With the support of USU, Lewis said he expects more commercial interest will emerge in the near future.

Photo credit: Utah State University