Diel biochemical and photosynthetic monitorization of Skeletonema costatum and Phaeodactylum tricornutum grown in outdoor pilot-scale flat panel photobioreactors.

Diatoms are currently considered valuable feedstocks for different biotechnological applications. To deepen the knowledge on the production of these microalgae, the diel pattern of batch growth, photosystem II performance, and accumulation of target metabolites of two commercially relevant diatoms, Phaeodactylum tricornutum and Skeletonema costatum, were followed outdoors in 100-L flat panel photobioreactors. S. costatum presented a higher light-to-biomass conversion resulting in higher growth than P. tricornutum. Both fluorescence data and principal component analysis pointed to temperature as a limiting factor for the growth of P. tricornutum. Higher protein and carbohydrate contents were found in P. tricornutum, whereas S. costatum fatty acids were characterized by a higher unsaturation degree. Higher productivities were found at 1 p.m. for protein, lipid, and ash in the case of S. costatum. Overall, S. costatum showed great potential for outdoor cultivation, revealing a broader temperature tolerance and increased biomass productivity than P. tricornutum.

System and method for research-scale outdoor production of microalgae and cyanobacteria.

Eukaryotic microalgae and cyanobacteria have recently reemerged as promising organisms in the effort to develop sustainable options for production of food and fuel. However, substantial discrepancies consistently arise between laboratory and outdoor cultivation, and gains demonstrated using laboratory technologies have not paralleled gains observed in field demonstrations. For these reasons, a low-maintenance system and process for research-scale outdoor cultivation of a variety of both freshwater and marine microalgae and cyanobacteria was developed. Nine genera were evaluated in the system, demonstrating cultivation of both laboratory model and commercial-production organisms. Hundreds to thousands of grams of dry biomass could be produced in a single growth cycle, suitable for a variety of uses including inoculum generation, protein production, and biofuel applications. Following testing in outdoor stock-ponds, Scenedesmus and Nannochloropsis were grown semi-continuously in an 8000 L airlift-driven raceway, yielding in total over 8 kg of dry biomass for each strain.