Biofilm cultivation of marine dinoflagellates under different temperatures and nitrogen regimes enhances DHA productivity

Abstract

Dinoflagellates contain large amounts of omega-3 fatty acids, including the nutritionally important docosahexaenoic acid (DHA). However, their cultivation in suspensions is characterized by low growth rates. Twin-layer porous substrate photobioreactors (TL-PSBRs) have been shown to support growth of different microalgal species, including the robust dinoflagellate Symbiodinium voratum. In the present study, the potential of cultivating marine autotrophic dinoflagellate species in a TL-PSBR for DHA production was explored. Based on initial screening experiments, two Symbiodinium species with high biomass and DHA productivities were selected: the symbiotic Symbiodinium microadriaticum CCAC 2475 B and the free-living Symbiodinium voratum CCAC 3869 B. The effects of three different temperatures (17, 22 and 27°C) and nitrogen regimes (nitrate, ammonium and nitrogen-free) on biomass growth, total lipid accumulation and fatty acid methyl esters (FAMEs) content, with emphasis on DHA, were evaluated. The two lower temperatures (17 and 22°C) enhanced growth and total lipid accumulation of S. microadriaticum CCAC 2475 B and S. voratum CCAC 3869 B. Cultivation at 22°C and nitrogen limitation led to a significant positive effect on DHA productivity. Symbiodinium. microadriaticum CCAC 2475 B reached a DHA productivity of 145.4 mg m −2 day −1 and DHA content in the dry biomass of 2% (w/w) after 4 days of nitrogen depletion. The results of the present study demonstrated that autotrophic dinoflagellates, when cultivated on a TL-PSBR, produce comparable amounts of lipids and fatty acids to other commercially used microalgal species including the valuable DHA.

A mini review on challenges and opportunities in dinoflagellates cultivation

“…However, peridinin and toxins contents have also aroused, albeit simple, interest in cultivation aimed at the biotechnological applications of Symbiodinium spp. biomass (Benstein et al, 2014;Langenbach & Melkonian, 2019;Tsirigoti et al, 2020).…”

Comparative Transcriptomic Analysis Uncovers Genes Responsible for the DHA Enhancement in the Mutant Aurantiochytrium sp.

“…Eggs naturally contain small amounts of DHA, but new DHA enriched eggs can contain up to 258.2 mg of DHA per egg [11]. Furthermore, marine microalgae including chrysophyta [12], dinoflagellate [13], and diatom [14], are also regarded as a promising alternative as the primary producer of the EPA and DHA in marine food webs. Marine eukaryotes, such as Thraustochytrids [15] and Schizochytrium, with abundant FA contents, have emerged as promising producers of n-3 LC-PUFAs [16].…”