A sustainable route to plastic degradation

The summary is the same as the one originally submitted for the project. A third of all plastics end up in the environment with 165 million tons ending up in the oceans creating vast accumulations of life choking rubbish, which has devastating consequences for marine life, recently highlighted in Blue Planet (BBC). Only 9% of plastic gets recycled and even then, only a limited number of times due to thermal degradation. The remaining plastic pollutes the environment or sits in landfill sites, where it can take up to 500 years to decompose, leaching toxic chemicals into the ground. Traditional plastics such as the polyester poly (ethylene terephthalate) (PET) are made from oil based raw materials. PET makes up almost one sixth of the world's annual plastic production of 311m tons. Around 41m tons of PET was produced in 2013 and this is projected to increase to 73m tons by 2020. Despite being one of the more commonly recycled plastics, only half is ever collected and recycled, considerably less actually ends up being reused. Bioplastic polyesters (bio-based and/or biodegradable) offer a sustainable alternative given their lower carbon footprint and often faster decomposition. Unfortunately, at present, a significant proportion of next generation biodegradable polyesters end up in landfill, where anoxic degradation results in significant atmospheric release of methane, a greenhouse gas 23 times more potent than carbon dioxide (CO2). Aims The overall project aims to implement the degradation of PET and several bioplastic polyesters in Cupriavidus metallidurans; a robust metabolically diverse microorganism cell factory, capable of utilising CO2 as a carbon source. Objectives The primary objective being to express non-native Petase and Lipase proteins in C. metallidurans and couple this to biomass. Engineered strains will be subject to metabolomic characterisation (metabolic phenotyping) to estimate intra and extracellular metabolic fluxes. Conventional liquid chromatography (LC)-mass spectrometry (MS)-based metabolomics and stable isotope-assisted metabolic pathway analysis methods, coupled with 13C flux will be utilised to predict in vivo enzyme reaction rates, unravelling metabolism and providing exemplar kinetic data, allowing for the development of designer strain with improved plastic degradation. Directed evolution will be utilised to engineer enzymes with improved degradation properties. Designer strains will then be characterised in continuous fermentation.