Tetradesmus lagerheimii: an algal solution for pollutant-tolerant aquaculture tailwater management and metabolomic insights

Wastewater management presents a significant environmental challenge, necessitating its repurposing for high-value products to enhance economic viability and sustainability. This investigation examines the potential of a pollutant-tolerant algal strain Tetradesmus lagerheimii in treating aquaculture tailwater, while exploring its metabolomic mechanisms. Compared to Chlorella vulgaris, T. lagerheimii exhibited superior adaptability under co-cultivation with indigenous bacteria (IB), achieving a higher Biomass Growth Rate by 109.4 %. The algal-bacterial system proved highly effective, removing 91.2 % of dissolved inorganic nitrogen (DIN), 48.4 % more than the algal monoculture, and achieving near-complete removal of dissolved organic carbon (DOC) and soluble reactive phosphorus (SRP). Metabolomic profiling revealed 17 significantly upregulated bacterial-derived metabolites, including 2-ketobutyric acid and vanylglycol, which positively correlated with algal growth. Exogenous addition of these compounds enhanced algal biomass by up to 1.3-fold. Furthermore, specific bacterial genera (Blastomonas, Porphyrobacter) were selectively enriched in the phycosphere, suggesting a beneficial association. This research demonstrates the potential of T. lagerheimii for sustainable aquaculture tailwater management.