Effect of Wavelength of Intermittent Light on the Growth and Fatty Acid Profile of the Haptophyte Isochrysis galbana

Abstract

The haptophyte Isochrysis galbana is widely used as a food source forbivalve aquaculture as it is rich in fatty acid. In this study, theeffect of different colors of intermittent light on the multiplicationof cells of I. galbana and their fatty acid composition wasinvestigated. 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%, lightintensity; 52 mu mol photons m(-2) s(-1), water temperature; 20 degreesC).The concentration of cells and fatty acid composition were measured at 6days after the beginning of cultivation.Cell concentration of I. galbana increased with time. The cellconcentration on the 6th day under the blue light condition wassignificantly higher than in other light conditions. The numbers ofcells under white, red, and green light were 65%, 60%, and 40% of theblue 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 blueintermittent light was approximately double that under white continuouslight, and therefore the amount of fatty acids available is alsoconsidered to be approximately double.