Sustainable Synthesis of Silk-Inspired Polymers

A. Connor, M. Koffas, R.H. Zha
Rensselaer Polytechnic Institute,
United States

Keywords: recombinant silk, sustainable polymers, microbial upcycling


Nature provides extraordinary examples of high-performance, biodegradable polymers with properties often surpassing those of man-made plastics. Protein-based plastics are particularly interesting because their precisely controlled sequences can give rise to complex properties based on the synergy of diverse intermolecular interactions. For example, silk fibroin, a class of proteins produced by many insects and arachnids, is an archetypal elastomer with an unrivaled combination of strength and toughness. Using engineered microbes, protein-based plastics can be made from renewable resources. Our research aims to develop new platforms for producing silk-inspired polymers with well-defined chemical structures and targeted material properties. These innovations have potential applications in environmental sustainability (e.g. biodegradable plastics for a circular economy) and in healthcare (e.g. materials for tissue engineering and drug release). In particular, we will discuss recent work in our lab demonstrating the production of synthetic silk by bacteria that metabolize polyolefin-derived hydrocarbons as a sole carbon source. This effectively enables upcycling of waste recalcitrant plastic, such as polyethylene, into high value bespoke proteins. We will additionally discuss recent findings regarding the metabolic challenges associated with producing recombinant silk in bacteria, and we will present our work in engineering a new E. coli strain with significantly improved capacity for synthesizing recombinant silk.