BIO-ESPRESSO: Bio-Electrochemical System for Product REcovery from Spent Substrate cOffee waste (FoodBioSystems DTP)

This project aims at the conversion of waste coffee, an abundant sub-product of the coffee industry, into value-added compounds through the application of bioelectrochemical systems called microbial fuel cells (MFCs). In MFCs, the metabolic activity of microbial communities attached to an electrode converts energy-rich organic matter into an electric current. In these systems, modifications in the operation conditions can be applied to direct the activity of the community, towards the synthesis of compounds of interest. This project will explore the feasibility of using coffee waste as feedstock for MFCs, with the view of developing a scalable technology for production of added-value biochemical or platform chemicals.

Why coffee waste? Coffee is one of the world's largest agricultural commodities: approximately 8bn kilograms are grown annually worldwide. The European Union is the largest importer of coffee, part of which is re-exported either as green or processed coffee. In 2013, the EU imported 3bn kilograms of coffee, accounting for approximately 45% of all exports of coffee.

The main residue produced by the coffee industry is called waste coffee ground (WCG), obtained in the industrial production of instant coffee and in the domestic and commercial coffee preparation. This residue is highly polluting due to their high content of organic matter, and potential toxicity, due to the presence of caffeine, tannins, and polyphenols.

WCG contains high amounts of cellulose, hemicellulose and lignin, free sugars, protein fat, and oils, lipids, triglycerides, and fatty acids. It also contains compounds of potential interest, such as antioxidants (e.g. caffeic, ferulic, p- coumaric, sinapic, and 4-hydroxybenzoic acids) and essential oils and terpenes.

Current methods of disposal of those residues only convert organic matter into unrecoverable (unusable) products. Coffee waste is mostly discharged into sanitary landfill or anaerobic digestion processes, and, at domestic scale, composting. However, the composition of the residue suggests their use as a source of precursors for specialty and platform (bio)chemicals. Due to the complexity of the system, conversion based on chemical processes is not possible without pre-treatment. Nevertheless, it should be possible to utilize the highly specific metabolic reactions present in microorganisms to convert those substrates into value-added compounds or their precursors.

We propose to use Bioelectrochemical systems to obtain value-added compounds from coffee waste used as feedstock in microbial fuel cells. Based on the chemical composition of coffee waste, we will identify which of the compounds could be obtained by the concerted metabolic activity of microbial species. Using bioinformatic tools, we will analyse natural microbial communities to identify the metabolic pathways able to convert a given substrate into a given product. We will also study pre-treatment strategies to improve the degradability of the waste by the selected microbial communities . The combination of all those approaches will allow us to design MFCs fed with solid and liquid feedstocks and careful selection and manipulation of operation parameters, will direct the process towards the production of added value molecules, decreasing the organic content of the original material and generating a less toxic product with lower content of pollutants.

This is a multi-, cross-disciplinary research proposal, as it straddles from microbial metabolism to biochemical engineering, through the combination of chemistry, microbiology, and bioelectrochemistry. This project involves Systems Biology, through the application of metabolic modelling, bioinformatics and the analysis and design of intercellular processes for bio-production; Synthetic Biology, through the rational design of microbial communities with specific and directed metabolic capabilities; a combination of biotechnological and chemical approaches, to inspire, guide, and deliver the transformation of bio-based building blocks into high added value molecules; application of bioinformatics and computational biology tools (e.g. bio-prospection, data analysis, metabolic modelling) for the identification and utilization of metabolic pathways to exploit microbial metabolic capabilities for bioprocess development.

About the FoodBioSystems DTP

The FoodBioSystems Doctoral Training Partnership (DTP) brings together six university partners: University of Reading, Cranfield University, University of Surrey, Queen’s University Belfast, Aberystwyth University, and Brunel University London. The Partnership’s vision is to develop the next generation of bioscientists with in-depth knowledge and technical expertise of food systems and biological processes across the Agri-Food system from pre-farm to post-fork. They will become the urgently needed experts - able to transform the food value chain and address challenges of sustainability, efficacy, authenticity and safety in food production systems whilst delivering better nutrition and concomitant health benefits for society. The DTP is currently advertising 36 projects. From these, it is expected 24 studentships will be awarded to the strongest application to start their studies in October 2022.

The successful applicant should have a background in either Microbiology or Microbial Biotechnology, or Chemical, Biochemical or Environmental Engineering. Appropriate training will be provided to complement the scientific background of the applicant. Interest and engagement with scientific research, possibly demonstrated by a successful undergraduate research project or a training placement.

This studentship is available for UK and international students.

IELTS requirements: The standard requirement is for a score of 6.5 or above (or equivalent) with 6.0 in each individual category, in an IELTS Academic test taken in the last 2 years. 

Department of Nutritional Sciences.