Semi-continuous cultivation of the mixotrophic dinoflagellate Gymnodinium smaydae, a new promising microalga for omega-3 production

Abstract

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL-1 , with an average growth rate of 0.7 d-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.

Antibacterial Activity and Amphidinol Profiling of the Marine Dinoflagellate Amphidinium carterae (Subclade III)

“…Microalgae constitute a polyphyletic and heterogeneous group of protists that have been portrayed as promising bioresources to further exploit owing to the scalability of their cultivation and the range of bioactive molecules they are known to biosynthesise [9,33]. The marine dinoflagellate genus Amphidinium has been of interest for the production of several bioactive compounds [34][35][36].…”

Effects of aeration and centrifugation conditions on omega-3 fatty acid production by the mixotrophic dinoflagellate Gymnodinium smaydae in a semi-continuous cultivation system on a pilot scale

“…Therefore, the analysis results were expressed as the fatty acid compositions and contents of G. smaydae + H. rotundata. According to Lim et al (2020), the fatty acid composition and content of only G. smaydae cells were similar to those of G. smaydae cells with H. rotundata cells, when the density of H. rotundata was <1% of that of G. smaydae.…”

“…By repeating these steps, G. smaydae was cultivated semi-continuously in the predator culture tank. In the predator storage tank, 80 or 90 L of G. smaydae culture was maintained without added prey for 1 day under the same culture conditions (Lim et al 2020), and G. smaydae cells in the predator storage tank were harvested 1 day later through centrifugation to analyze the density and fatty acid contents.…”

“…In addition, the mixotrophic dinoflagellate Gymnodinium smaydae contains high DHA levels, i.e., 43% of the total fatty acid contents, which is the highest DHA content among currently examined microalgae, excluding C. cohnii (Jiang et al 1999, Jiang and Chen 2000. Therefore, this dinoflagellate is a promising candidate for high DHA production (Lim et al 2020). This species, which was isolated and classified as a new species in Korea in 2014, is identified as a non-toxic species feeding directly on other species using its peduncle and exhibiting rapid growth (Kang et al 2014, Lim et al 2018.…”

“…This species, which was isolated and classified as a new species in Korea in 2014, is identified as a non-toxic species feeding directly on other species using its peduncle and exhibiting rapid growth (Kang et al 2014, Lim et al 2018. A 10-L semi-continuous cultivation system for G. smaydae was previously developed, and the cell density and fatty acid contents of the species were stably maintained for 43 days (Lim et al 2020). We have successfully developed a 100-L cultivation system for the heterotrophic dinoflagellate Noctiluca scintillans (You et al 2022).…”