(664d) Biosynthesis Strategies for Controlling the Nanostructure of Polyhydroxyalkanoate Block-Copolymers

Polyhydroxyalkanoates (PHAs) are microbially-synthesized polymers that are both biodegradable and produced from renewable feedstocks.  Despite these favorable characteristics commercial demand for PHAs remains limited.  This is partly due to a greater cost advantage for petroleum-derived polymers but also because of the small number of unique material properties which are currently available from PHAs.  In response to this need for further technological development of PHAs, our laboratory is exploring novel materials with controlled polymer nanostructure.  Already we have shown how mass spectroscopy-controlled biosyntheses can be used to create PHA, core-shell, nanoparticles as well as PHA block-copolymers which show superior toughness compared to random copolymers.  In this paper we describe the continuing work of our laboratory to create novel PHAs with controlled nanostructure.  We have engineered new polymer synthase enzymes with expanded substrate specificity to allow the synthesis of unique block-copolymers from structurally dissimilar monomers.  Additionally we have engineered new E. coli host strains with altered metabolic functionality to increase the flux of monomer supply pathways and reduce the time required to switch between different monomer types.  With these new capabilities along with mass-spectroscopy controlled biosynthesis, we aim to explore how the physical interaction between dissimilar monomers as well as the size of separate polymer domains affects the material properties of this important class of biopolymers.