Ryan Putman, Utah State University
Engineering
Spider silk possesses superior mechanical properties to most other biological or man-made materials. In particular, research has demonstrated that spider silk is as strong as Kevlar, yet much more elastic. The unique feature of both strength and elasticity naturally piques interest in numerous scientific fields (e.g. medical sutures, automobile seat belts, or athletic performance wear). However, the limiting factors in using spider silk on a commercial scale are the production of sufficient protein product and the ability to do so in a cost-effective manner. An additional challenge is due to the territorial and cannibalistic nature of spiders, which makes harvesting their silk from large “spider farms” an infeasible task. To overcome these limitations, an approach using synthetic biological engineering principles has been employed. This emerging field of study provides a powerful tool, the use of standard biological parts called BioBricks. Using these standard DNA parts, a genetic circuit with the necessary regulatory components was engineered to recombinantly produce a synthetic spider silk protein in the microorganism Escherichia coli, which will provide a more consistent and sustainable source of spider silk than by harvesting directly from spiders. Expression of this recombinant protein has been verified through SDS-PAGE protein gels and subsequent protein immunoblot. The next step is to create a genetic circuit that will be used to secrete the spider silk protein outside of the E. coli bacterium. This could greatly reduce the downstream processing costs associated with protein purification as well as potentially increase overall yield. Therefore, a genetic tag that targets products for secretion has been fused to the spider silk coding regions. Further testing is required to determine the difference in overall protein yield from secreting as opposed to non-secreting strains of the engineered bacteria. Once these values are determined, the production can be optimized and scaled-up.