Global omics study of Tetraselmis chuii reveals time-related metabolic adaptations upon oxidative stress.

Microalgae species encounter oxidative stress in their natural environments, prompting the development of species-specific adaptation mechanisms. Understanding these mechanisms can offer valuable insights for biotechnological applications in microalgal metabolic manipulation. In this study, we investigated the response of Tetraselmis chuii, an industrially important microalga, to H₂O₂-induced oxidative stress. Exposure to 0.5-mM H₂O₂ resulted in reduced cell viability, and higher concentrations led to a drastic decline. After 1 h of exposure to H₂O₂, photosynthetic capacity (Qy) was negatively impacted, and this reduction intensified after 6 h of continuous stress. Global multi-omics analysis revealed that T. chuii rapidly responded to H₂O₂-induced oxidative stress within the first hour, causing significant changes in both transcriptomic and metabolomic profiles. Among the cellular functions negatively affected were carbon and energy flow, with photosynthesis-related PSBQ having a 2.4-fold downregulation, pyruvate kinase decreased by 1.5-fold, and urea content reduced by threefold. Prolonged exposure to H₂O₂ incurred a high energy cost, leading to unsuccessful attempts to enhance carbon metabolism, as depicted, for example, by the upregulation of photosystems-related PETC and PETJ by more than twofold. These findings indicate that T. chuii quickly responds to oxidative stress, but extended exposure can have detrimental effects on its cellular functions. KEY POINTS: • 0.5-mM H₂O₂-induced oxidative stress strongly affects T. chuii • Distinct short- and long-term adaptation mechanisms are induced • Major metabolic adaptations occur within the first hour of exposure.