Synthetic Biology Approach to New Sustainable Materials

Abstract

Rapid industrialization and an abundance of cheap petroleum fueled the production and development of a great variety of synthetic polymers in the twentieth century. Over the past 60 years, these materials have become a part of the fabric of modern life. They are pervasive; from the polyurethanes in our cars and furniture, to the polypropylene in a state of the art medical implant, we rely on synthetic polymers every day of our lives, to accomplish tasks both trivial and critical. However, production of these chemicals from petroleum feedstocks is unsustainable and damaging to the environment. One potential option for more sustainable production is to use microbial fermentation to generate industrial chemicals. Microbial fermentation offers the opportunity to produce chemicals from biomass, making the compounds produced renewable feedstocks. Furthermore, the conditions used for, and byproducts produced from, microbial fermentation are benign. However, many microbial monomers face challenges in terms of economic viability and utility. With this in mind, my PhD research has focused on developing engineering systems for production of novel and viable monomers, as well as implementation of biological monomers for material applications. Using metabolic engineering, I have implemented the first heterologous pathway for production of dipicolinic acid, an aromatic di-acid that could be used as a biological replacement for isophthalic acid, a major component of the performance polymers Nomex® and polybenzimidazole, as well as a useful additive in many other polymers. By working with collaborators, I have used ancestral reconstruction to improve the production of anhydromevalonolactone, a monomer that can serve as a sustainable alternative to poly(acrylate). Finally, I have worked to establish a new platform for developing zwitterionic materials. In this project, we were able to engineer E. coli to produce N-acetyl-serine, a compound that can be dehydrated to form an acrylate monomer with a protected amine. I then polymerized this monomer with styrene and developed zwitterionic coatings that show improved resistance to cell adhesion. Overall, my work has contributed to the development of new metabolic pathways and material applications of biologically-derived monomers.