Hydrogen and biofuel production in the chloroplast

Abstract

Plastids are the compartments in which oxygenic photosynthesis of higher plants and eukaryotic microalgae converts the energy of sunlight into chemical energy. The latter is used by green cells to generate the whole palette of organic molecules needed to build a cell. Mankind has made use of the green powerhouses from the beginning of its existence on, but in the last decades, products other than food or fire wood have gained importance. Facing the deprivation of fossil fuels and climate changes due to anthropologically caused greenhouse effects, we want to use photosynthetically converted light energy as an energy source to generate renewable energy carriers. Above all, the synthesis of biodiesel made from plant or algal lipids is a promising strategy. As the cultivation of microalgae does not compete with food production, research focuses on understanding and engineering lipid biosynthesis in these unicellular organisms. Additionally, in contrast to higher plants, some green algae are capable of using the process of photosynthesis for the generation of another biofuel: molecular hydrogen. In this chapter, the pathways resulting in the generation of hydrogen and lipids in the plastid are reviewed. Additionally, proven and anticipated targets of biotechnological optimization are highlighted.