Optimization of photosynthesis, growth, and biochemical composition of the microalga Rhodomonas salina

an established diet for live feed copepods in aquaculture

Minh Vu Thi Thuy, Claire Douëtte, Thomas Allan Rayner, Christina Vinum Thoisen, Søren Laurentius Nielsen, Benni Winding Hansen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The cryptophyte Rhodomonas salina is widely used as feed for copepod cultures. However, culturing conditions to obtain high-quality algae have not yet been efficiently optimized. Therefore, we aimed to develop a cultivation protocol for R. salina to optimize its nutritional value and provide technical recommendations for later large-scale production in algal photobioreactors. We studied photosynthesis, growth, pigments, fatty acid (FA) and free amino acid (FAA) composition of R. salina cultured at different irradiances (10–300 μmol photons m−2 s−1) and nutrient availability (deficiency and excess). The optimal range of irradiance for photosynthesis and growth was 60–100 μmol photons m−2 s−1. The content of chlorophylls a and c decreased with increasing irradiance while phycoerythrin peaked at irradiances of 40–100 μmol photons m−2 s−1. The total FA content was maximal at optimal irradiances for growth, especially under nutrient deficiency. However, highly unsaturated fatty acids, desired components for copepods, were higher under nutrient excess. The total FAA content was highest at limiting irradiances (10–40 μmol photons m−2 s−1) but a better composition with a higher fraction of essential amino acids was obtained at saturated irradiances (60–140 μmol photons m−2 s−1). These results demonstrate that quality and quantity of FA and FAA of R. salina can be optimized by manipulating the irradiance and nutrient conditions. We suggest that R. salina should be cultivated in a range of irradiance 60–100 μmol photons m−2 s−1 and nutrient excess to obtain algae with high production and a balanced biochemical composition as feed for copepods.
Original languageEnglish
JournalJournal of Applied Phycology
Volume28
Issue number3
Pages (from-to)1485-1500
Number of pages16
ISSN0921-8971
DOIs
Publication statusPublished - 19 May 2016

Bibliographical note

This is a post-peer-review, pre-copyedit version of an article published in Journal of applied Phycology. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10811-015-0722-2

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