Microbial electro-photosynthesis (MEPS) as a bioelectronic platform for organic synthesis
Abstract
Approved for Public ReleaseThe complex biochemical pathways of microorganisms are considered a crucial step in achieving a sustainable, fossil-fuel free production of organic compounds for biomaterials, biofuels, and the chemical industry. Photosynthetic algae and cyanobacteria can perform this production directly using solar energy and CO2, providing an efficient avenue for these bio-factories from available resources. Yet, when compared to other light-harvesting efforts, such as photovoltaics, photosynthetic micro-organisms suffer from low efficiencies. The Microbial Electro-PhotoSynthesis (MEPS) system developed by our group is a bio-electronic hybrid. MEPS utilizes electrical energy for water splitting, delivering electrons to photosynthetic bacteria. A modified Synechocystis sp. PCC 6803 strain that has photosystem II deleted is used in MEPS so that electrons are obtained from a cathode through a redox mediator. Through this process, an increase in efficiency, rate of growth, and carbon fixation from solar energy is expected. MEPS also allows growth of cyanobacteria at extremely high light intensities that would otherwise be inhibitory to the non-modified, wild-type strain. A major challenge in MEPS is how to efficiently deliver electrons via the electron redox mediator. The proposed work will expand the knowledge of redox mediators to increase the electrical current delivered to cyanobacteria and other photosynthetic microorganisms. A library of mediators will be evaluated and tested in MEPS reactors with the goal to increase electron flow tocyanobacteria. The project will develop mathematical models based on transport, electrochemical reduction and biological oxidationof redox mediator within the MEPS platform. These models will predict growth and product formation in MEPS. The project#s goal isalso to expand MEPS applications by testing new microorganisms (Synechococcus and Rhodopseudomonas) that are known to have a fastergrowth than Synechocystis sp. PCC 6803 (model organism). Finally, the project will demonstrate bioproduct formation (D-lactate) inMEPS using a genetically modified pathway in Synechococcus sp. PCC 11901.The identification of optimal conditions for this bio-electrical interface is of interest to MEPS applications, but also a major goal in bioelectronics research. The learnings obtained fromthis research can be used for MEPS and other bioelectronic interfaces applications of interest to the DoD (e.g., biosensors, bioelectronic control, bioinspired computing). In all these possible technologies, the development of efficient electron transport among a wide variety of biological cells is desired. The general approach of using redox mediators can allow us to extend the knowledge in MEPS to other systems, biological hosts, or technological applications.The MEPS system is a novel approach to grow photosynthetic microorganisms at higher light efficiencies and a new approach to produce biofuels, bioproducts,and biomass from CO2, carbon-negative processes of interest to DoD and the major scientific community. MEPS takes advantage of higher intensity light systems that are not possible when PSII protein is present. MEPS is an inspirational example of bio-electronic technologies where the strengths of natural and artificial systems are combined through electrochemistry.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2023
- Source ID
- N000142312104
Entities
People
- César I. Torres
Organizations
- Arizona State University
- Office of Naval Research
- United States Navy