Microbial Electrochemical System: extracellular electron transfer from photosynthesis and respiration to electrode

Sammanfattning: Popular Abstract in English The global energy consumption is increasing regularly due to the increased population and economic development. In contrast the primary energy sources, fossil fuels, are declining substantially. The combustion of fossil fuels contributes to the global climate change via greenhouse effects. To minimize these negative effects a carbon-neutral energy production is demanded. To guarantee a secured supply of a cost-effective sustainable clean energy production is one of the greatest challenges in the 21st century. Solar energy is the most abundant among all other renewable energy sources such as hydroelectricity, geothermal energy, and wind energy. Solar energy is the most ubiquitous around the world and the largest exploitable renewable energy resource. The amount of solar energy radiating from the sun to the earth in one hour is greater than the entire human annual global energy demand. Biological photovoltaics (BPVs) is emerging as a potential energy generating technology, where photosynthetic organisms are used to convert solar energy into electrical energy. Photosynthetic organisms in BPVs use solar energy for photolysis of water and provide electrons to the system. They are self-sustainable, inexpensive to maintain their growth culture and stored respiratory metabolites inside the cells could be used to generate electrical energy even in the dark. However, the photo-excited extracellular electron transfer (EET) from photosynthetic organisms to electrodes is one of the great challenges in BPVs. In this thesis we have studied the photo-electrochemical communication of various photosynthetic materials. We investigated the photo-excited EET from thylakoid membranes (TMs) from spinach, purple bacteria, and cyanobacteria as well as from eukaryotic algae. Besides that we have investigated the electrical wiring of heterotrophic microorganisms to electrodes for possible use in microbial electrochemical systems (MESs). These findings could have significant impacts in photosynthetic energy conversion, light sensitive bioelectrochemical devices and in biological fuel generation.