Production of bespoke biopolymers with controllable composition and microstructure

The accumulation of plastic waste in the environment is a real and current concern [1], a consequence of our ever increasing use of ever plastics, especially in single use packaging, and the environmental persistence of these commonly used, non-biodegradable, petrochemical derived materials. Polyhydroxyalkanoates (PHAs) are a family of microbially produced, biodegradable biopolymers which are produced by various microorganisms as an intracellular energy store. PHAs can be produced from renewable, non-crude oil derived feedstocks and a range of interesting novel applications exist, including in the biomedical field. The main challenges which must be addressed if PHAs are to be widely used as replacements for conventional plastics are the high production costs and inconsistent PHA structure and properties, which lead to difficulties in polymer processing.

To be able to utilise PHAs more widely we need to better our understanding of the link between production and the material properties, as well as improve the yield and productivity of PHA producing fermentations. We already have an understanding of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer production in an extreme halophile, Haloferax mediterranei, [2] and have demonstrated that with controlled feeding of volatile fatty acids (VFAs) we are able to directly control both PHBV composition and microstructure [3]. This allows us to produce copolymers with a preselected 3HV fraction and to also preferentially produce random, block or blend copolymers.

The aims of this PhD project are;

- To further investigate the effect of VFA feeding on the mechanical properties of PHBV block copolymers and to produce triblock, or greater (A-B)n, type polymers .
- To characterise and application test the resulting PHBV block copolymers.
- To increase the productivity of PHBV producing fermentations though bioprocess engineering.

This project involves biochemical engineering, polymer science and materials characterisation and testing and is suitable for candidates with a background in chemical engineering, biochemical engineering, microbiology, biotechnology or materials science.