BIOSCIENCE FOR RENEWABLE RESOURCES AND CLEAN GROWTH - Expanding Synthetic Biology using Biocompatible Reactions

The emerging field of biocompatible chemistry aims to "repurpose" chemical reactions traditionally used in organic chemistry to operate within living microorganisms and alongside engineered metabolic pathways.[1] This enables the bio-production of non-natural small molecules of industrial value that cannot be accessed via synthetic biology and would otherwise remain reliant on petrochemicals. However, despite significant progress in recent years, a detailed understanding of the molecular descriptors that define a successful biocompatible reaction are lacking. This is particularly intriguing from an academic perspective, as many biocompatible catalysts have been designed to operate in a non-aqueous environment (e.g. organic solvent) in the absence of cells. One reason for this could be the presence of microbial membranes. These amphiphilic structures are ubiquitous to all microorganisms and serve to protect the cell interior from external factors using surface glycans and at least one phospholipid bilayer. However, the organic environment of the cell membrane can also accumulate hydrophobic metabolites (e.g. styrene) and has been hypothesised, yet not proven, to impart a positive influence on biocompatible reactions by co-localising reaction components in the cell envelope. This is supported by a recent observation from our lab that membrane-associated micelles can both co-localise the components of a biocompatible reaction and accelerate product formation in engineered E. coli.[2] However, these theories remain just that and the influence of the cell membrane on biocompatible reactions remains completely unexplored.

This PhD project will investigate the effect(s) of microbial membranes on biocompatible reactions in vitro and in vivo. We will also use modern synthetic biology techniques to manipulate the cell membrane, creating intracellular 'nano-reactors' to localise biocompatible reactions inside living bacteria with the aim of creating new pathways to industrial compounds and products from sustainable feedstocks such as CO2, lignin and PET plastic waste.[3,4] Supported by four global industrial partners, this project combines modern synthetic biology, microbiology and chemical biology to push the boundaries of what is currently possible in industrial biotechnology using engineered microorganisms.

The multidisciplinary nature of this project will enable the PhD student to develop a strong proficiency in a range of biological and chemical laboratory techniques, including 1D/2D-NMR, mass spectrometry, HPLC, GC, DNA sequencing and assembly methods, PCR, transmission electron microscopy and the use of bioreactors for large-scale fermentations.