Coordinated Intracellular–Extracellular Metabolic Remodeling Underlies the Exceptional Tolerance of Tetradesmus sp. XDA-R28 to Sodium Dodecylbenzenesulfonate (SDBS) Stress

Sodium dodecylbenzenesulfonate (SDBS) is a widely used anionic surfactant whose environmental persistence and ecotoxicity raise concerns about aquatic ecosystems. Although microalgae serve as vital bioindicators of aquatic pollution, how intracellular and extracellular metabolic responses coordinate under SDBS stress remains poorly understood. In this study, Tetradesmus sp. XDA-R28 was selected from the Xinjiang Special Environmental Algae Culture Collection (XJSAC). Based on concentration–response growth assessment, 30 mg/L SDBS was selected for further analyses because it elicited physiological responses without markedly inhibiting growth. At 30 mg/L SDBS, the apparent removal efficiency reached approximately 89.6% after 72 h, as determined by the methylene blue active substance (MBAS) method. Catalase (CAT) and superoxide dismutase (SOD) activities, malondialdehyde (MDA) and proline contents, and untargeted intracellular and extracellular metabolomics were analyzed. SDBS exposure altered antioxidant responses, energy and amino acid metabolism as well as LysoPC and PC profiles, suggesting changes in glycerophospholipid metabolism. Concurrently, the extracellular metabolic network underwent dynamic adjustments, with changes in antioxidant- and secondary-metabolism-related compounds, including isorosmanol, myricanone, broussinol, and dihydrocoriandrin. These findings highlight coordinated intracellular–extracellular metabolic responses and support further evaluation of XDA-R28 for surfactant-contaminated water treatment. The contributions of biosorption, cellular uptake, and biotransformation to SDBS removal require further investigation.