Doctoral thesis

The transition towards a sustainable economy requires innovative solutions to reduce industrial emissions and harness renewable energy sources. In this context, bioelectrochemical systems (BES) are an emerging technology that combines biotechnology and electrochemistry to produce energy and high value-added compounds from microorganisms. This project focuses on optimising the electroactive capabilities of the bacterium Pseudomonas putida and its integration into microbial consortia to improve the performance of BES and their industrial application. To this end, four key areas will be addressed: 

1. Genetic engineering and optimisation of BES in P. putida The three mechanisms of extracellular electron transfer (EET) will be improved: direct (cytochromes), indirect (redox mediators such as flavins) and via nanowires. This will maximise electron exchange in planktonic cultures and biofilms, improving both electricity production and 2,3-BDO synthesis. Key in this respect is that such EET mechanisms enable the electrode to act as an external electron acceptor that allows the growth and maintenance of P. putida under anoxic conditions. This could solve a key problem for their use in industrial bioproduction contexts.
2. Development of synergistic microbial consortia Consortia between P. putida and exoelectrogenic bacteria such as Shewanella oneidensis will be established, complementing their capabilities to optimise electricity bioproduction. In addition, the integration of saprophytic fungi (Ophiostoma piceae and Talaromyces amestolkiae) will be evaluated to take advantage of plant waste and incorporate metabolic properties that improve the degradation of recalcitrant pollutants.
3. Waste valorisation and design of catalytic biofilms Multicellular biofilms will be studied by studying quorum sensing chemical interactions to increase stability and electron transfer efficiency. This will improve the efficiency of conversion of substrates into chemicals of interest and bioelectricity.
4. Metabolic modelling for systemic optimisation E-exchange processes will be incorporated into the P. putida genomic model to identify genetic modifications and improve performance in BES. The project promises significant advances in sustainable bioproduction, contributing to clean energy generation and waste valorisation in the framework of a circular economy, supported by the expertise of the CIB-CSIC group in microbial systems and protein engineering.