Regular articleScaled up from indoor to outdoor cultures of Chaetoceros gracilis and Skeletonema costatum microalgae for biomass and oil production

•Scaled up cultures of C. Gracilis and S. Costatum from indoor to outdoor was studied.•Minimum doubling times of 2.77 days were obtained on a pilot scale for both species.•Lipid content of 23.7% and 28.5% were achieved for C. Gracilis and S. Costatum.•Palmitic and stearic were the predominant fatty acids on both algal species.

Adaptability and growth of two marine diatoms, little known today, Chaetoceros gracilis and Skeletonema costatum microalgae, have been studied. Indoor cultures in 5 L photobioreactors under controlled conditions and outdoor cultivation in 80 L photobioreactors under uncontrolled environmental conditions have been evaluated. Maximum biomass productivities of 28.0 ± 0.16 and 32.0 ± 0.60 mgL−1d−1 were obtained when S. costatum was cultivated on large-scale with air or air + CO2 bubbling, respectively, and specific growth rates about 0.13-0.25 d−1 were exhibited. Biomass productivities slightly lower were achieved by C. gracilis and doubling times nearly half, 2.79-2.87 to 4.95-6.30 days, were obtained in pilot scale cultures against laboratory scale. Finally, lipid extraction and its analysis were conducted. Palmitic and stearic acids were the major components. Therefore, scale up cultivation of these two species is a feasible process and it allows to obtain a biomass with high potential for biodiesel production.

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