Generating Energy From Photosynthetic Microorganisms
Photosynthetic microorganisms, including algae and cyanobacteria can export electrons in a light-stimulated phenomenon called ‘exoelectrogenesis’, which has enormous potential applications for sustainable generation of electricity from light and water. The photosynthetic cell could be interfaced with electrodes and electron mediators to yield bio-photoelectrochemical cells (BPECs) that transform light into electrical power and produced hydrogen for sustainable energy. There are two main mechanisms for extracellular electron transfer (EET) between the cell and the electrode: One is direct extracellular electron transfer (DEET), involving direct contact and electron transfer between the cell and the electrode via conductive extracellular appendages or redox proteins on the cell surface. The second is indirect extracellular electron transfer (IEET), involving electron mediators diffusing from the cell to the electrode. The mediators could be continuously produced metabolites that are oxidized at the electrode surface, or metabolites that cycle between the cell and the electrode.
In this research I will focus on IEET by tracking NADPH as a native electron mediator as well as also different electron mediators.
In BPEC systems, one of the factors limiting power outputs and efficiency is the molecular damage caused to the photosynthetic protein machinery due to intense radiation exposure for long time periods, a phenomenon known as photoinhibition. This exposure leads to formation of Reactive oxygen species (ROS), hydrogen peroxide and other radicals that could be harmful to the photosynthetic system.
Chlorella ohadii (C.ohadii), is a single cell algae which was isolated from soil-crust beds in the Nitzana desert, Israel. Originating from an arid desert area, C. ohadii is a good candidate for improving our BPEC set-up, having a robust photoprotection mechanism and fast proliferation rate.
My research will focus on using C.ohadii as a photosynthetic organisms for generating energy and hopefully to improve efficiency of previous organisms. I will try to answer on questions related to EET mechanism when using algae in BPEC. Following achieving deeper insights into this system, I will further work to improved the BPEC with electrochemical and biological approaches.
This diagram describes exoelectrogenesis in photosynthetic microorganisms. NADPH is the native electron mediator while vitamin B1 and FeCN could be use as alternative mediators. DCMU is a herbicide that inhibit the electron transfer between PSII and PSI and use as a tool to investigate the electron transfer source [Shlosberg et al., Catalysts 2021, 11(10), 1220].
