SPIDER SILK: A MIRACLE MATERIAL DERIVED FROM . . . GOATS?

Rachel Parish

Southeastern Illinois College

Student Rachel Parish gave this informative speech in the 2007 finals of an annual national tournament hosted by Phi Rho Pi, a group that fosters public speaking and debate for junior and community college students throughout the United States. In this speech about an object, Rachel explains the astonishing strength and versatility of a material that may surprise her listeners—spider silk. Rachel’s speech is organized categorically, or by topic, with the main points describing spider silk’s properties, the means of producing it, and a number of its applications.

In the classic book Charlotte’s Web, we find the story of a loving spider saving pitiful Wilbur from becoming bacon through messages spun in her webs. However, this is not the first time that such power has come from such a seemingly delicate medium.

In ancient Greece, spider webs were used to stop bleeding in open wounds. Aborigines use spider silk in small fishing lines. And how could we not mention Peter Parker’s amazing ability to swing from buildings and catch the bad guys, all through the power of the web?

Now, that last example may be fictional, but Spider-Man’s formidable weapon, the web, is no less amazing in real life. Spider silk is one of the strongest fibers known. It is incredibly fine and tough, and as the November 9, 2006, London Daily Mail tells us, “When woven into a fiber, it is weight-for-weight five times stronger than steel.” •

So we know that the spider web, or spider silk, is tough, and over the past decade we found it to have both practical and medicinal benefits for us. However, to date we’ve never actually seen any of the benefits. Why? Well, gathering large quantities of spider silk has been relatively impossible until now. You see, while we may not have a real-life Spider-Man, we do have Spidergoat. This is a transgenic goat that’s producing spider silk on a much larger scale than Charlotte ever could. •

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Today we’ll learn about the value of spider silk and how these scientifically altered goats are allowing its once unavailable advantages to become a reality. First, we’ll look at the background of spider silk; second, the goat’s role in its production; and finally, its current and future uses. •

Let’s first learn about the value of spider silk and how these goats are allowing its once unobtainable potential to be a reality. According to BBCNews.com, July 12, 2006, “Spider silk has been admired by scientists for decades due to its unique combination of strength, toughness, flexibility, and light weight; its thickness is less than one-tenth the size of a human hair, but it has 400,000 pounds per square inch of strength.” To put this in perspective, if you built a massive spider web in which each strand was the width of a pencil, you could catch a 747 jumbo jet in full flight.

So if spider silk is indeed the strongest fiber on earth, why haven’t we taken advantage of this miracle material before? The June 16, 2006, Science and Technology tells us that “spiders are incredibly hard to farm so silk can be harvested, mainly due to a spider’s nature.” • Basically, if you put two spiders together in a confined space, due to their cannibalistic nature, you’ll suddenly find yourself with only one spider.

In addition, even when they are contained properly, you can milk only so much silk from a spider. A study this past November by Randy Lewis of the University of Wyoming showed that even when dealing with large spiders, on a good day you can gather only 1.5 mg of silk. Thus, even if you could get the cannibals to get along, a spider farm capable of raising enough useful silk would simply be impossible. •

However, all that has now changed. Last year, Nexia Biotechnologies—a Canadian research firm—began looking at normal farm goats as the key to bringing spider silk to the masses. According to Christopher Helman in Forbes.com, February 19, 2001, Jeffrey Turner, a geneticist at Nexia, discovered that the silk gland of spiders and the milk gland of goats were almost identical, but the goat’s is obviously much bigger. At the turn of the millennium, Nexia began implanting spider genes into goats in order to breed “spider goats” capable of producing spider silk in large enough quantities for commercial use. The end result was Webster and Pete, the first two goats born with the spider-web gene.

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So now that we’ve looked past the roadblocks to cultivating spider silk by showing the creation of a feasible silk resource thanks to Webster and Pete here, let’s examine the process by which the spider gene was passed on to the goats. • According to the January 15, 2006, issue of the journal Nature, “Spider silk starts out as a substance called scleroprotein, which shoots out from the spider’s web spinnerets. . . . [I]t dries into a thread, and when this thread hardens we end up with something that looks a little more familiar to us.”

When Nexia discovered that the silk glands of spiders were similar to goats’ mammary glands, Nexia applied this discovery to dairy goats. Taking a goat embryo, Nexia injected the spider gene controlling the creation of silk into the goat’s mammary cells. These cells then took effect and activated the female goats when they started lactating, or creating milk for their young. When the lactation period in the goat is over, these cells stop functioning and stop producing silk until the goat starts lactating again. According to Materials Today, December 2002, Jeffrey Turner reports that each transgenic goat is “capable of making ‘literally miles’ of this spider silk–based material.” Fifteen thousand goats could produce enough silk to meet projected medical and industrial demands. Plus, because they’re not cannibalistic, we’re able to farm goats on a large scale. •

However, the spiders do have one advantage: the goats can’t spin the silk they produce, so then there’s a weaving process. As explained in the October 10, 2006, airing of Modern Marvels on the History Channel, “The goats are milked as they normally would be, then the milk is put into a centrifuge that spins rapidly. This causes the silk fibers to separate from the milk so they can be extracted. Salts are then added to the silk fibers to help them harden. Once this step is completed, you have what researchers have dubbed ‘bio-steel.’” According to the June 3, 2006, Journal of Biological Chemistry, this new silk made from spider-enhanced goats is the same strength and composition as normal spider silk. The method is environmentally safe, and the goats are not harmed in any way during the milking process. •

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So we’ve examined the background of spider silk, its genetic switch to goats, and how it has evolved into bio-steel. But what benefits can we anticipate from this evolution? Will the use of goat silk bring us from the research lab to the battlefield and the operating room? •

Biotech Week, December 13, 2006, reports that bio-steel is now being used to construct bulletproof clothing for soldiers and police. Dr. Randolph Lewis, a biologist at the University of Wyoming, stated in the same issue of Biotech Week that Kevlar, the most popular fiber used in bulletproof vests, is very difficult to make and requires a chemical processing that is highly damaging to the environment. Unlike Kevlar, spider silk bio-steel is made in water-based conditions, and it’s completely biodegradable. • In addition, in tests performed in early 2006 at the University of Wyoming, it was proven that when woven into a bulletproof vest, spider silk was stronger and more durable than the now-outdated Kevlar.

Yet bio-steel’s most promising benefits are medicinal rather than military. According to the Royal College of Surgeons of England, in “Secrets of the Spider Web,” March 9, 2007, “the demand for spider silk in the medical profession is high with a myriad of potential uses such as scaffolds, bone grafts, or ligament repair.” The real strength of bio-steel as an internal support is its great wall strength and its ability to naturally dissolve over time without the need of additional surgeries. In addition, the spider silk bio-steel can be used as wonderful, durable, and biodegradable stitches that can be used in the most delicate of areas due to the material’s thinness and strength. What’s more, as Science, June 23, 2006, reports, spider silk bio-steel provokes a very low immune response when introduced into the body. What does that mean for us? Well, heavy immune responses cause rejection of artificial medical implants, thus making bio-steel a much more successful option than any previous materials. •

The main challenge for researchers is breeding enough goats to meet the demand for bio-steel. However, according to the October 31, 2006, CBC News, “If breeding continues as is, then the University of Wyoming’s herd of goats alone will be bountiful enough to meet commercial demands by the end of 2008.” In 2006 they produced over 5,200 pounds of spider silk, and just this past August the UW researchers received a quarter-million-dollar grant from the Department of Defense to expand their output, so the future of goat bio-steel looks very promising.

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Today we looked at the background of spider silk, the goat’s role in its production, and finally its current and future applications. We can see the value of goat bio-steel for both military and medicinal uses, and in time perhaps we could imagine America’s favorite web slinger changing from Peter Parker to Pete and Webster. •