Metabolic mechanisms of marine microalgae in response to selenite and selenate: Implications for selenium enrichment and environmental remediation.

Microalgae serve as effective carriers for selenium enrichment and accumulation within aquatic ecosystems. They possess the ability to convert inorganic selenium into organic forms, primarily selenium-containing amino acids and proteins, thereby playing a crucial role in transferring selenium through the food chain. However, the mechanisms underlying marine microalgae's responses to selenite (Se) and selenate (Se) remain unclear. In this study, we employed the metabolic response mechanisms of marine microalgae to various selenium forms. This study analyzed the metabolic mechanisms of Phaeodactylum tricornutum and Dunaliella salina under different selenium forms treatments. The results indicated that Se and Se suppressed the Calvin cycle in marine microalgae, thereby decelerating photosynthetic metabolism and growth. Se specifically inhibited carbon, lipid, and amino acid metabolism, whereas Se enhanced these processes in marine microalgae. Additionally, compared to P. tricornutum, D. salina accumulated more beneficial metabolites (eg. selenomethionine levels increased 4.5-fold) and suffered less growth damage under Se treatment, suggesting a better selenium-enriched carrier. Understanding these metabolic mechanisms in response to selenium offers valuable insights for developing strategies to remediate and remove high concentrations of inorganic selenium from the environment.