Why Isn't Spider Silk Farmed Despite Its Unmatched Strength?

Spider silk, renowned for its properties that are often compared to steel, has long intrigued scientists and engineers alike. Despite its remarkable strength, spider silk has not yet been widely commercialized or farmed. This article delves into the reasons behind this gap, exploring historical uses, current agricultural challenges, and recent advancements in spider silk production through genetic engineering.

Historical Uses and Decline in Utilization

Historically, spider silk has had a range of applications, from producing gun sights and graticules to its use in textiles. However, its utilization largely declined in the mid-20th century. By the 1960s, traditional uses had petered out, with the last spider known for this purpose being pensioned off. The decline was due to the lack of practical and scalable methods for harvesting spider silk.

While modern materials such as Kevlar and carbon fibers are now stronger than spider silk, researchers have found ways to enhance spider silk's properties. For instance, feeding carbon nanotubes to spiders resulted in silk fibers that were five times stronger than normal spider silk, reaching a strength comparable to some synthetic fibers.

Challenges in Farming Spider Silk

One of the primary reasons spider silk remains underutilized is the cannibalistic nature of spiders. Unlike silkworms, which produce cocoons of silk, spiders create webs with shorter, non-continuous strands of silk. This makes it difficult to produce continuous threads of silk, much like those created through Kevlar.

Efforts to Harvest Spider Silk

Efforts to harvest spider silk directly from spiders have proven challenging. While Nexia Biotechnologies developed a genetically engineered approach to spider silk production, incorporating the golden orb spider’s spider silk gene into goats, the company went bankrupt before commercialization could proceed.

Similarly, efforts to integrate spider silk genes into silkworms have only produced mixed results, failing to achieve the desired quantities and properties.

Genetic Engineering Approaches

One promising approach to producing spider silk is through genetic engineering. Companies like Kraig Biocraft Laboratories have successfully genetically modified silkworms to produce spider silk. By gifting the golden orb spider’s spidroin gene to silkworms, they have created silk with potential commercial applications.

Bolt Threads, a Silicon Valley startup, has taken a different approach, using transgenic bacteria and yeast fermentation to produce mass-scale synthetic spider silk. This method shows potential for large-scale production and commercialization.

Challenges in Large-Scale Production

Despite genetic engineering advances, two significant challenges remain in large-scale spider silk production:

Spidroin Synthesis

Spidroin, the protein that makes up spider silk, has a unique structure with orthogonal arrangements of beta strands and sheets. Specific amino acid sequences ensure the protein's strength, while hydrophobic residues contribute to its durability. Mimicking this natural process is a complex task that remains a challenge for researchers.

Spider Silk Spinning Process

Converting the synthetic protein solution into fine, continuous fibers is another obstacle. The process involves using spinnerets, found in spiders, but mimicking this machinery is difficult. The various types of spider silk (with different amino acid compositions and functions) complicate this task further.

The Future of Spider Silk

Despite these challenges, the future of spider silk as a commercial biomaterial is promising. With continued research and innovation, the applications of spider silk extend far beyond textiles, including aeronautics, infrastructure, and wound healing.

The success of startups like Bolt Threads and the ongoing advancements in genetic engineering suggest that the potential of spider silk as a sustainable and versatile biomaterial is being realized. As more research and investment are directed towards this field, the world of spider silk-like fabrics may soon become a reality.

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