Effects of Sodium Selenate on Growth, Selenium Forms, and Nutritional Quality of Chlorella pyrenoidosa

In this study, C. pyrenoidosa were cultured with seven different concentrations of Na₂SeO₄ (0-10 mg/L), and the effects of Na₂SeO₄ on the growth, Se-forms, and nutritional quality of C. pyrenoidosa were explored. The results showed that at the concentration of 0.5 mg/L Na₂SeO₄, the C. pyrenoidosa were plump and healthy; the contents of biomass, soluble protein, lipids, and TPUFA reached the highest level; the total Se content in C. pyrenoidosa increased with the increasing Na₂SeO₄ concentrations. However, the proportion of organic Se in C. pyrenoidosa. reached the highest value of 87.58% at the concentration of 0.5 mg/L Na₂SeO₄. Among organic Se forms, SeMet accounted for the largest proportion, while MeSeCys accounted for a relatively smaller proportion, but SeCys₂ was not detected. The addition of Na₂SeO₄ (except for ≤0.5 mg/L) reduced the contents of photosynthetic pigments in C. pyrenoidosa. In addition, the antioxidant capacity of C. pyrenoidosa first increased and then decreased with the increasing Na₂SeO₄ concentrations, but different enzymes exhibited different tolerances to Na₂SeO₄. Based on the above research results, 0.5 mg/L Na₂SeO₄ concentration is recommended for the production of Se-rich C. pyrenoidosa. Our findings will provide a theoretical basis and practical references for the development of Se-rich C. pyrenoidosa health care products.