Effect of different light spectra on the growth and biochemical composition of Tisochrysis lutea

Abstract

We determined the effects of various light spectra (white, green, blue, and red) on the growth rate, biochemical composition, and fatty acid content of Tisochrysis lutea (Haptophyta, Isochrysidales) maintained in batch cultures. The growth rate peaked with white and blue light, and the lowest rate was observed with green and red light. The chlorophyll a content differed significantly between light spectra and growth phases—higher values were recorded with blue and red light in both growth phases. The proximal composition varied significantly with growth phases and light spectrum. In the exponential growth phase, protein content was significantly greater with blue light and in the stationary phase with green light. The level of carbohydrates in the exponential growth phase was significantly higher for white light, but unchanged in the stationary growth phase between light spectra. The lipid percentages were similar in the exponential phase but differed significantly in the stationary growth phase. The lipid percentages peaked in the stationary growth phase with red and green light. The highest eicosapentaenoic acid (EPA) levels were seen in white light in the exponential growth phase and under green light in the stationary growth phase. Docosahexaenoic acid (DHA) levels were greatest in the exponential growth phase with red light and in the stationary growth phase with green light. Blue light increased the DHA content in both growth phases. We conclude that T. lutea alters its metabolic pathways and experience shifts in growth rate, proximate composition, and fatty acid content, depending on the type of light used.