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Dinoflagellates are a natural resource for unique secondary metabolites and pigments,which have great potential in the application in biomedical drug development, cosmetics and aquaculture. However, biotechnological cultivation of dinoflagellates in the common suspension-based closed photobioreactors (PBRs) has been proven to be problematic due to the sensitivity of the cultures against the associated shear forces. To overcome these and other constrains of suspension systems immobilised cultivation of the dinoflagellate Symbiodinium voratum is performed using a Twin-Layer porous substrate biofilm reactor (TL PSBR). In this thesis, the optimisation of the production of biomass and anti-oxidant peridinin, the main carotenoid of S. voratum, in TL PSBRs was investigated. In the optimisation process a maximal biomass productivity of 7.8 g m−2 was recorded at a light intensity of 600 µmol photons m−2 s−1 and 2 % CO2. Due to the persistent linear growth of the S. voratum biofilm a maximal biomass yield of 305 g m−2 was gained which is higher than in other biotechnological cultivated microalgae in the TL PSBR, like Haematococcus pluvialis. The peridinin production in S. voratum was enhanced by exposure of the biofilm to low light and high temperatures. While the peridinin yield (0.93 g m−2) and productivity (28.0 mg m−2 d−1) was highest at a light intensity of 100 µmol photons m−2 s−1, maximal peridinin concentration of 1.8 % of dry weight was obtained at 15 µmol photons m−2 s−1. Due to opposing conditions for biomass and peridinin production a two-step cultivation approach, composed of the combination of growth and peridinin enhancing phases was performed. Thereby, in this thesis, a maximal peridinin productivity of 51.4 mg m−2 d−1 was obtained. In addition up-scaling of the immobilised culture of S. voratum in a horizontal fleece-based TL PSBR, with a growth area of 2 m2, was shown to generate under comparable conditions as in the bench-scale experiment identical results. Therefore the TL PSBR presents an alternative biotechnological system for the large scale application of dinoflagellates. |
