Effects of metal-organic frameworks (MOFs) on growth and toxin production of Alexandrium minutum and corresponding mechanisms

The global spread of harmful algal blooms (HABs) has become a serious environmental problem, which urgently needs innovative control methods. This study explored the suppression efficiency of copper- and zinc-based metal-organic frameworks (MOFs) on growth and toxin production of the toxigenic microalga Alexandrium minutum . The physical characterization data confirmed that Cu-MOF has a higher surface area (1207 m 2  g −1 ) than Zn-MOF (56.9 m 2  g −1 ). Both materials could inhibit the growth of A. minutum with a concentration-dependent pattern. Comparatively, the Cu-MOF resulted in notable inhibition even at low concentrations. However, Zn-MOF stimulated growth at low concentrations but showed an inhibitory effect at higher doses (≥5 mg L −1 ). Both MOFs caused oxidative stress, alteration of cell membrane, and photosynthesis disruption. Additionally, transcriptomic findings revealed a major change of nutrient metabolism. Genes related to phosphorus uptake were mostly up-regulated, while those for nitrogen assimilation were largely down-regulated. The decrease in medium phosphorus and change in nitrogen levels also reflected this transcriptional response and demonstrated the imbalance in nutrient ratio. Furthermore, both MOFs, specifically at elevated concentrations, reduced overall production of paralytic shellfish toxins (GTX1, GTX4, GTX2 and GTX3). This study showed the potential utility of MOFs as targeted porous materials for HAB mitigation.