Effects of Culture Medium Enrichment with Zinc on Astaxanthin Accumulation in a New Strain of the Microalga .

High Zn concentrations in microalgal cells that produce astaxanthin as a feed additive can reduce the symptoms of malnutrition in aquatic animals. Therefore, in this study, we analysed the effect of Zn in the culture medium on the growth of a newly isolated microalgal strain ZY24. Zn and white light stress altered the pigment content in microalgal cells. In addition, high Zn concentrations in the culture medium altered cell morphology and chlorophyll fluorescence and also increased intracellular Zn accumulation. Further, an optimal Zn concentration in the culture medium promoted the synthesis of astaxanthin and other pigments. When the concentration of Zn was 45.5 mg L, ZY24 produced 0.31 mg g astaxanthin, whereas the total zinc content of the microalgae was 4337 mg kg. This study confirmed that microalgae have a high capacity for Zn enrichment, providing a theoretical basis for studying Zn enrichment in microalgae. Furthermore, Zn supplementation to stimulate astaxanthin production in microalgae is a practical method to enhance their nutritional value.