"However, gathering the silk from farm-raised spiders, which are territorial and cannibalistic, is not an option. Firms attempting to make spider silk synthetically have copied relevant genes from spiders and inserted them into organisms, such as Escherichia coli, that can express the protein. The protein, though, is complex, and producing silk that is as strong as nature’s has proven elusive."
Spider Silk is a material that has captivated the interest of a plethora of industries due to its diversity of applications. Although being just a protein, spider silk is five times stronger than steel and three times tougher than Kevlar. Strength is measured by how much weight the material can withstand while toughness is the amount of kinetic energy it can take without rupturing. Because of these characteristics the material has been desired for the manufacturing of cables and bulletproof vests, but as of recently the potential applications have expanded far beyond that. The more we look into this glycine and alanine potent amino acid strand the more aware we become of its thermal conductive and antimicrobial properties. This puts the material into a category of heat management materials as well as medical materials for wound patches, artifical tendons, and implant coatings.
The possibilities are exciting, but surprisingly the proteins’ non-fiber applications are the only ones that are commercial as of today. Those applications are of course in cosmetics and shampoos. According to AMSilk, the German company manufacturing these products, the spider silk makes the skin feel “supersmooth”, and adheres to keratin, which is the main structural protein in hair. AMSilk is using genetically engineered E.coli to produce the protein in a fermentation process. The company has already synthesized close to twenty different silk varieties, which are all derived from the DNA of the European garden Cross spider.
Most excitingly the company has already outsourced production showing that this is indeed scalable technology. Large-scale output for fibers and high performance textiles are expected to come from this firm after 2015, and they are not the only people working on manufacturing spider silk on the large scale.
Three other firms (Araknitek, KAIST, and Spiber) have announced that they are using E.coli to manufacture synthetic spider silk, but two other companies are taking a different approach. A Michigan based company known as Kraig Biocraft Laboratories is in the process of scaling up to produce a hybrid spider-silkworm silk fiber from transgenic silkworms. Ten years ago Kim K. Thompson, founder and CEO of Kraig Labs, had this dream of transgenic silk worms, but the idea was limited by the technology at hand. Eventually Thompson found Malcolm J. Fraser Jr, a biology professor at the University of Notre Dame, to transpose genes between species making Kim’s dream a viable business plan. Last October, Kraig Labs came to an agreement with Warmick Mills to commercialize the silk with textiles, so it will be interesting to see the direction at which they take. As of now specific plans are not being discussed publically, but Thompson has already had a talk of outsourcing a second facility to Vietnam, where there is already a very strong silkworm industry.
The second company is not putting all their eggs in one basket, or means of producing the silk, but rather four. Araknitek, a company spun off from technology developed at Utah State, has developed four different hosts spanning three different biological kingdoms that can carry the spider’s silk genes: goats, silkworms, E.coli, and alfalfa. The herds of transgenic goats carry a gene from orb weaver spiders, which is the strongest type of spider silk. The goats produce the protein in their milk, which is then extracted using simple purification techniques. The goat approach has been proven to be good for small medical applications like sutures and artificial ligaments, but the isolation process is energy intensive.
Araknitek has proven that transgenic plants and animals can produce the protein, but scaling up with those methods are not commercially viable. The only technology that makes economic sense for a spider silk company is E. coli systems. It will be interesting to see the applications of this material in the near future, as the technology to produce it gets cheaper and more readily available.
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