Solar Energy is the most abundant renewable energy source available for our Planet. Light energy conversion into chemical energy by photosynthetic organisms is indeed the main conversion energy step, which originated high energy containing fossil deposits, now being depleted. By the way, plant or algae biomass may still be used to produce biofuels, as bioethanol, biodiesel and bio-hydrogen, bioproducts (antioxidants, biostimulants, fertilizers, pharmaceuticals) or biomass for human nutrition or animal feed. Microalgae exploitations have the considerable advantages of being sustainable and not in competition with food production, since not-arable lands, wastewater and industrial gasses can be used for algae cultivation. However, this potential has not been exploited yet, since biomass yield on industrial scale obtained up to now were relatively low and with high costs of production. The main limitation encountered for sustained biomass production in microalgae by sunlight conversion is low light use efficiency, reduced from the theoretical value of 10% to 1-3%. This low light use efficiency is mainly due to a combined effect of reduced light penetration to deeper layers in highly pigmented cultures, where light available is almost completely absorbed by the outer layers, and an extremely high (up to 80%) thermal dissipation of the light absorbed. This project as aimed to investigate the molecular basis for efficient light energy conversion into chemical energy, to significantly increase the biomass production in microalgae combining a solid investigation of the principles of light energy conversion with biotechnological engineering of algal strains. SOLENALGAE project allowed to understand to molecular details of photoprotection and heat dissipation of the light energy absorbed in microalgae going deep into details about the protein subunits involved, their interactors, and the protein domains and specific residues at the base of the quenching activity observed, also highlighting the energy pathways and the molecular species at the base of the excitation energy quenching. This information was then considered to plan different biotechnological intervention in different microalgae species, which allowed to boost photosynthetic activity and production of specific high value products as astaxanthin, on e of the strongest antioxidant molecule found in nature, proteins for human nutrition of biostimulants to be used in agriculture.
