Culture of dinoflagellates in a fed-batch and continuous stirred-tank photobioreactors: Growth, oxidative stress and toxin production

Dinoflagellates are potentially important sources of high-value toxins in biomedical, toxicological and chemical research programs. However, the difficulty to culture them in bioreactors limits the development of new products. L1 and other usual dinoflagellates media have been shown to not support an elevated cell growth. The present work evaluated the nutrient uptake rates and nutrient cell yields of Protoceratium reticulatum in different culture modes that allowed to maintain a high concentration of cells under a quasi-steady-state concentration of nutrients. Monitoring of the cellular ROS and lipoperoxides contents in low-shear bioreactor cultures is proposed as culture health-indicating parameters. The amount of yessotoxins (YTXs) produced by the strains studied to date was very different among them and are importantly conditioned by the culture conditions; therefore the strain selection is a key issue. In this work, we evaluated the growth and toxin production of two strains of P. reticulatum which are known to produce very different YTX quantities. The maximum productivities were obtained in continuous mode (up to 214 ng mL−1 day−1) achieving a sustainable production during more than 4 months. Finally, the purpose of the dinoflagellate toxins in nature and their relation with the nutrient abundances were discussed.