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Genetic engineering of microbes and regulation of charge transfer dynamics for high performance biophotovoltaics

English title Genetic engineering of microbes and regulation of charge transfer dynamics for high performance biophotovoltaics
Applicant Boghossian Ardemis
Number 182972
Funding scheme Bilateral programmes
Research institution Institut des sciences et ingénierie chimiques EPFL - SB - ISIC
Institution of higher education EPF Lausanne - EPFL
Main discipline Chemical Engineering
Start/End 01.12.2019 - 30.11.2023
Approved amount 347'909.00
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All Disciplines (5)

Chemical Engineering
Material Sciences
Electrical Engineering

Keywords (4)

metabolic modelling; genetic engineering; biological photovoltaics; systems modelling

Lay Summary (French)

Les technologies photovoltaïques existantes s'appuient sur des matériaux synthétiques pour récupérer l'énergie solaire et convertir l'énergie collectée en électricité. Bien que beaucoup de ces technologies aient un rendement élevé, elles ont souvent aussi des coûts élevés et des émissions de CO2 lors de la fabrication. ces technologies s’inspirent souvent des processus de collecte de lumière que l’on trouve dans la nature, comme la photosynthèse, mais ne tirent pas profit de leurs capacités robustes, peu coûteuses et capables d’absorber le carbone. Bien qu'un nombre croissant de technologies photovoltaïques émergentes soient des matériaux biologiques qui tirent parti de ces capacités naturelles, elles affichent souvent des rendements relativement faibles.
Lay summary

L'objectif de ce projet est de concevoir un dispositif photovoltaïque à haute efficacité basé sur des matériaux biologiques, en particulier des bactéries vivantes capables d'effectuer la photosynthèse. Pour réaliser un dispositif biologique à haute efficacité, nous allons mettre en œuvre trois approches distinctes et complémentaires basées sur (i) l'ingénierie biologique des bactéries; (ii) ingénierie électrochimique d'électrodes, de médiateurs et de configurations de dispositifs; et (iii) la modélisation informatique des interactions entre la bactérie et le dispositif électrochimique.

Ce projet vise à relever les défis énergétiques auxquels notre société est confrontée aujourd’hui en proposant une technologie d’énergie solaire viable sur le plan industriel. En plus de fournir une source d'énergie renouvelable, cette technologie contribuera également à la séquestration du carbone, en répondant aux préoccupations actuelles concernant les niveaux croissants de CO2 dans notre environnement.

Direct link to Lay Summary Last update: 06.11.2019

Responsible applicant and co-applicants

Gesuchsteller/innen Ausland

Associated projects

Number Title Start Funding scheme
189631 Integrated Microscope for Live-Cell and Single-Molecule Imaging 01.01.2020 R'EQUIP


Mimicking the machinery of natural processes to develop artificial devices have been quite successful in various domains of science and engineering. Especially for conversion of sunlight to electricity/fuels, the photosynthetic processes in plants/microorganisms which optimized the light harvesting process for several billion years is being mimicked to develop photoelectrochemical devices, including dye-sensitized solar cells and water splitting systems. In the latter systems, the role of biological components are replaced by synthetic materials, but efforts were also being made to utilize natural components themselves in the devices. In solar cells, chromophores from photosystem I & II were employed as light absorbers. However, the stability of these bioextracts under illumination remain inferior compared to their living photosynthetic counterpart. So it is preferable to use living systems which can self-repair on photodamage and it is an attractive prospect for building low cost and stable solar energy conversion devices, in future. In spite of this potential, the state-of-the-art of biophotovoltaic (BPV) or ‘living photovoltaic’ systems show power conversion efficiencies (PCE) below 0.1 % and is primarily due to the low short-circuit current density. One of the key issues is the insulating outer layer of microbes that prevents the transfer of photogenerated charge carriers from the chromophore to the external circuit. In this proposal, we would like to address this specific issue in BPV to improve PCE. We are proposing a triangular approach wherein the problem will be addressed by the way of microbial engineering, electrochemical engineering and systems modelling, using the model cyanobacterium Synechocystis sp. PCC6803. The microbial engineering approach will be focused on modifying the microbe’s metabolism to enhance the extracellular electron transfer to the photoanode and to minimize competing inherent mechanisms for dissipating excess energy. Direct extracellular electron transfer to the electrode will be achieved by the way of bioengineering exoelectrogenicity in the photosynthetic bacteria, Synechocystis sp. PCC6803. These bioengineered strains, along with the wildtype cells, will be electrochemically characterized to identify the possibility of indirect and possible direct extracellular electron transfer in the presence and absence of soluble mediators. The electrochemical approach, on other hand, will focus on identifying appropriate electron mediator to shuttle photogenerated electrons from the microbe to photoanode. The key to this task lies in finding the electrochemical potential of electrons at the point of extra cellular charge transfer. In the proposed work, electrochemistry of both wildtype cells and the bioengineered mutants will be investigated to identify the redox potential of the component that transfer the photogenerated to the external electron acceptor. Following the identification of potential, external redox mediators positive (w.r.t. to NHE) to the microbe will be selected and their efficacy in accepting charges will be investigated. Appropriate photoanode material that is selective to electron conduction and conduction band position that is positive to both the microbe and redox mediator will be identified. The goal of this part of the proposal is to find the right combination of microbe, redox mediator and anode, based on the redox potentials of each of these components. These components will be assembled into a biophotovoltaic devices based on a device architecture that is designed to avoid carrier recombination within the device, which decreases the overall conversion efficiency. The last in the triangular approach is the modelling & optimization of charge transfer within microbes and devices. The experimental charge transfer kinetics, in this biological network will be modelled to propose the optimized device design for high performance. All the parameters relevant to photocurrent generation starting from the absorption of solar photons to the electron extraction at the external contact will be simulated. Specifically, the quantum efficiency of photogenerated electrons from microbe to redox mediator, mass transport limitations redox mediator and charge carriers, parasitic recombination of electrons/holes and the catalytic ability of cathode for oxygen reduction, will be investigated in detail. Where ever available, experimental data will be used for the optimization. The feedback from the modelling will be used to decide further possibilities for improving the metabolic process in the biological medium and the device architecture, until an efficient biophotovoltaic device is obtained. This combined approach is unique, wherein we bring in the three different expertise, i.e. microbial engineering, electrochemical engineering of biophotovoltaic devices and systems modelling, to develop high performing biophotovoltaic devices.