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Competition Funded PhD Project (Students Worldwide)
Lignin valorisation to value-added chemicals in a net zero carbon bioprocess
Overview
Sustainable circular economies are intrinsically tied to renewable resource flows, where vast quantities need to be available at a central point of consumption. Abundant, renewable carbon feedstocks such as the second-generation lignocellulosic based biomass are available to create net zero carbon circular economies. The hexoses and pentoses in this feedstock can be efficiently valorised using biological routes, however lignin which comprises of about 40% of the lignocellulosic biomass is recalcitrant in nature and lacks efficient biocatalysts for converting the lignin monomers into value added products. Systems metabolic engineering has demonstrated its capability in designing and developing industrially potential microbial strains producing products from renewable feedstocks.
Within this multidisciplinary project, combining mutational studies based on targeted engineering of enzymes, integrating the mutated enzymes into the host and imposing selection pressure by evolutionary based selection will be used to select cell factories with enhanced lignin monomer (vanillin, guaiacol, phenol and cresol) utilisation, increased tolerance, enhanced product secretion etc. The project will screen multi-functional Cytochrome P450 enzymes which catalyses conversion of lignin monomers, into intermediates facilitating microbial uptake. Certain amino acid targets will be selected based on molecular dynamic simulations for enhanced substrate specificity and catalytic efficiency. Mutations will be implemented via site directed mutagenesis and in vitro enzyme assays will be performed to analyse the effect of the mutations. Selected mutated enzymes will be implemented into the host bacterial strains, Cupriavidus necator and Pseudomonas putida and evolved for enhanced substrate utilisation and tolerance in a continuous evolutionary fermentation strategy. Mixotrophic gas fermentation process will be developed to create a net carbon zero emission fermentation process with efficient titre, yield, and productivity metrics.
At the end of the process, we will be able to select bacterial strains with increased tolerance and utilisation capacity of the lignin derivatives with an optimised process producing value-added products. A comparative study will be performed between P.putida and C.necator in converting the lignin monomers to value-added products. This will open doors towards diverting the carbon from the lignin derivatives towards value-added products efficiently creating a sustainable biomanufacturing route, making use of the lignin fraction in the lignocellulosic feedstocks. The project brings multidisciplinary areas like synthetic biology and fermentation technology in creating sustainable lignin valorisation routes.
Closing Date: 18 February 2022
Funding Notes: Each studentship supports a full stipend, paid for three years at RCUK rates (for 2021/22 full-time study this is £15,609 per year) and full tuition fees. UK and international (including EU) candidates may apply. Please also read the full funding notes which include advice for international and part-time applicants.
Supervisors: Dr Rajesh Bommareddy, Dr W Singh, Prof G Black
Start Date: 1 October 2022
Full Description: For more information please click here.
For informal enquiries, please contact Dr Rajesh Bommareddy (rajesh.bommareddy@northumbria.ac.uk)