Team:Stanford-Brown/SB16 BioMembrane Nylon

Nylon-6 Biosynthesis

Nylon is a designation for a family of semi-aromatic polyamids that can be worked into various useful forms. Thin films of nylon have similar properties to polyvinyl chloride plastic wrap, capable of stretching under stress before tearing. Nylon fibers are lightweight and have high tensile strengths, making them very useful when woven into fabrics. Besides its applications in clothing, woven nylon is most commonly used in hot air balloon membranes and sailboat sails due to its durability. Properties of nylon materials such as tensile strength, heat resistance, and abrasion resistance can be increased by crosslinking the polymers using various methods. [1] The most common forms of nylon in the textile and plastic industries are nylon-6 and nylon-6,6, both of which have similar physical characteristics. While nylon-6,6 is a copolymer, nylon-6 is a homopolymer, making it a more appropriate candidate for biosynthesis. For these reasons, our team identified nylon-6 as one of our candidate biomembranes.

Nylon-6 is industrially produced through the chain-growth polymerization of caprolactam, the cyclical form of 6-aminocaproic acid (6-ACA). Our team investigated potential biosynthesis routes for this monomer, looking for pathways with common starting substrates to design a production system for 6-ACA that could be implemented on an extraterrestrial body. Past retrosynthetic analyses have uncovered two fermentative pathways for the production of 6-ACA, which both lacked required biocatalytic steps until 2015. [2][3] Last October, researcher Stefan Turk published a study detailing and potential candidates enzymes for these steps and characterizing their activity in vivo in E. coli. [4] With the novel nature of his work in mind, our team contacted Turk in request of a sample of his engineered strain eAKP-672 with the highest 6-ACA yield when grown in glucose containing medium. We hoped to adjust Turk's synthetic plasmid designs and/or make our own genomic edits to optimize the metabolic flux of his biosynthetic pathways. Turk replied in the affirmative, shipping us two separate cell samples containing plasmids pAKP-96 and pAKP-444, which held the six enzymes necessary to induce one of the two above mentioned pathways in E. coli.

References
1. http://www.ptonline.com/articles/radiation-crosslinking-boosts-nylon-properties
2. https://www.google.com/patents/US20140134681
3. https://www.google.com/patents/US20110091944
4. http://pubs.acs.org/doi/abs/10.1021/acssynbio.5b00129?journalCode