Effects of light quality on the growth, productivity, fucoxanthin accumulation, and fatty acid composition of Thalassiosira pseudonana.

Thalassiosira pseudonana, a fast-growing and nutritionally rich planktonic diatom, has been cultivated on a large scale as high-quality plankton feed. Despite this, studies exploring the impact of light quality on the growth and compositional attributes of this algal species are scarce. This study investigated the effects of five different light qualities—white, red, yellow, green, and blue—on the growth, biomass, fucoxanthin accumulation, and fatty acid composition and content of T. pseudonana. The results indicated that T. pseudonana achieved the highest growth rate and greatest biomass under white and blue light, with the poorest performance observed under red light. Moreover, fucoxanthin accumulation was most pronounced under blue light, reaching 4.729 ± 0.182 mg g-1, followed in descending order by yellow, red, white, and green light. The total lipid content was highest under yellow light at 34%, significantly surpassing the levels observed under other conditions, with the order of effectiveness being blue light > green light ≥ red light ≥ white light. Analysis of fatty acid composition revealed a greater diversity under blue light, with a total of 15 types, whereas green light yielded only 10 types. The proportion of unsaturated fatty acids was highest under blue light at 69.71%, followed by yellow, white, green, and red light. Specifically, the performance of polyunsaturated fatty acids (PUFAs) varied as follows: yellow light (36.7%) > blue light (34.09%) > white light (33.29%) > green light (23.67%) > red light (17%). The concentration of eicosapentaenoic acid (EPA) was significantly greater under blue (17.03%) and yellow (16.31%) light compared to other treatments, with the lowest concentration (8.84%) observed under red light. In conclusion, blue light significantly enhances the growth rate of T. pseudonana and fosters fucoxanthin accumulation. Both yellow and blue light are favorable for the accumulation of PUFAs and EPA. [ABSTRACT FROM AUTHOR]