Effect of Wavelength of Intermittent Light on the Growth and Fatty Acid Profile of the Haptophyte Isochrysis galbana
The haptophyte Isochrysis galbana is widely used as a food source for bivalve aquaculture as it is rich in fatty acid. In this study, the effect of different colors of intermittent light on the multiplication of cells of I. galbana and their fatty acid composition was investigated. I. galbana was cultivated under conditions of white, blue (dominant wavelength; 470 nm), green (525 nm), or red (660 nm) intermittent light (frequency; 10,000 Hz, duty ratio; 50%, light intensity; 52 μmol photons m−2 s−1, water temperature; 20°C).
The concentration of cells and fatty acid composition were measured at 6 days after the beginning of cultivation.
Cell concentration of I. galbana increased with time. The cell concentration on the 6th day under the blue light condition was significantly higher than in other light conditions. The numbers of cells under white, red, and green light were 65%, 60%, and 40% of the blue light condition, respectively.
I. galbana contains mostly lipids of 16:0, 16:1n-7, and 20:5n-3 (EPA), which account for approximately 50% of the total lipids.
In conclusion, the number of cells on the 6th day under the blue intermittent light was approximately double that under white continuous light, and therefore the amount of fatty acids available is also considered to be approximately double.
KeywordsFatty Acid Composition Total Lipid Duty Ratio Dominant Wavelength White Continuous Light
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