Biotechnological Optimization of Light Use Efficiency in Nannochloropsis Cultures for Biodiesel Production

Abstract

In the last years new renewable energy sources started to be exploited to compensate exhausting fossil fuels and minimize anthropogenic factors on climate change. Microalgae have reemerged as potential next-generation feedstock for biofuels and they are considered very promising on the long term, since they have a potentially high productivity per area and they can be grown on marginal land without competing with food crops. Our work is focused on the seawater microalga Nannochloropsis gaditana, which combines a fast growth rate with a strong accumulation of lipids and therefore yields great potential for these kinds of applications. Solar radiation provides all the energy supporting algae growth and lipids production and for this reason the available radiation must be exploited with the highest possible efficiency to optimize productivity and make their cultivation on a large scale competitive. Investigation of the bases affecting light use efficiency is thus seminal to elucidate the connection between light and the lipids/biomass productivity. To this aim we investigated the influence of different illumination regimes, nutrients availability and batch/ continuous cultivation on N. gaditana cultures productivity and light use efficiency. This information will be exploited for optimization of growing systems but also to design Nannochloropsis gaditana genetic manipulations. Strains with altered composition of the photosynthetic apparatus and modified regulation of photosynthesis are being selected and characterized to increase Nannochloropsis gaditana productivity in photobioreactors.