Mixotrophy in marine microalgae for renewable biomass production
Diatoms are unicellular eukaryotic algae (microalgae) and one of the most common and diverse type of marine phytoplankton. Thanks to a flexible cell metabolism, they dominate in environmental conditions normally unfavorable for photosynthesis, i.e. freezing seawater, low light intensity and short photoperiod. Moreover, diatoms are able to synthesize storage lipids (20-50% of cell dry weight) that can be used for production of renewable biomass and high-value fatty acids. However, the success of these microalgae as feedstock depends on lowering the production cost. The proposed project aims to develop mixotrophic cultivation (i.e. the simultaneous use of light and carbon dioxide for photosynthesis and organic carbon for respiration) to maximize growth and outdoor productivity for selected strains from the Swedish west coast. The focus will be on the bloom-forming coastal diatom Skeletonema marinoi (S. marinoi) whose sequence annotation is ongoing, and the recent knowledge on mixotrophic growth of the model diatom Phaeodactylum tricornutum will be employed. The main objectives will be: i) using the bloom-forming S. marinoi to better understand mixotrophic metabolism in diatoms; ii) exploring the optimal mixotrophic conditions for enhanced productivity of S. marinoi; iii) investigating the potential industrial applications of S. marinoi when cultivated under mixotrophy. To achieve these objectives, an interdisciplinary approach including computational, biophysical, analytical, biotechnological and biological methods will be employed. A mixotrophic outdoor cultivation of marine microalgae in the dynamic climate of the Swedish west coast could provide a higher total production of renewable biomass for industry.