Zhang Wenlin, Tan Nicole G J, Fu Baohui, Li Sam F Y
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Metallomics. 2015 Mar;7(3):426-38. doi: 10.1039/c4mt00253a.
Industrial wastewaters often contain high levels of metal mixtures, in which metal mixtures may have synergistic or antagonistic effects on aquatic organisms. A combination of metallomics and nuclear magnetic resonance spectroscopy (NMR)-based metabolomics was employed to understand the consequences of multi-metal systems (Cu, Cd, Pb) on freshwater microalgae. Morphological characterization, cell viability and chlorophyll a determination of metal-spiked Chlorella sp. suggested synergistic effects of Cu and Cd on growth inhibition and toxicity. While Pb has no apparent effect on Chlorella sp. metabolome, a substantial decrease of sucrose, amino acid content and glycerophospholipid precursors in Cu-spiked microalgae revealed Cu-induced oxidative stress. Addition of Cd to Cu-spiked cultures induced more drastic metabolic perturbations, hence we confirmed that Cu and Cd synergistically influenced photosynthesis inhibition, oxidative stress and membrane degradation. Total elemental analysis revealed a significant decrease in K, and an increase in Na, Mg, Zn and Mn concentrations in Cu-spiked cultures. This indicated that Cu is more toxic to Chlorella sp. as compared to Cd or Pb, and the combination of Cu and Cd has a strong synergistic effect on Chlorella sp. oxidative stress induction. Oxidative stress is confirmed by liquid chromatography tandem mass spectrometry analysis, which demonstrated a drastic decrease in the GSH/GSSG ratio solely in Cu-spiked cultures. Interestingly, we observed Cu-facilitated Cd and Pb bioconcentration in Chlorella sp. The absence of phytochelatins and an increment of extracellular polymeric substances (EPS) yields in Cu-spiked cultures suggested that the mode of bioconcentration of Cd and Pb is through adsorption of free metals onto the algal EPS rather than intracellular chelation to phytochelatins.
工业废水通常含有高浓度的金属混合物，其中金属混合物可能对水生生物产生协同或拮抗作用。采用金属组学和基于核磁共振波谱（NMR）的代谢组学相结合的方法，来了解多金属体系（铜、镉、铅）对淡水微藻的影响。对添加金属的小球藻进行形态特征、细胞活力和叶绿素a测定，结果表明铜和镉对生长抑制和毒性具有协同作用。虽然铅对小球藻的代谢组没有明显影响，但在添加铜的微藻中，蔗糖、氨基酸含量和甘油磷脂前体大幅下降，这表明铜诱导了氧化应激。在添加铜的培养物中加入镉会引起更剧烈的代谢扰动，因此我们证实铜和镉协同影响光合作用抑制、氧化应激和膜降解。全元素分析表明，添加铜的培养物中钾含量显著下降，而钠、镁、锌和锰的浓度增加。这表明与镉或铅相比，铜对小球藻的毒性更大，并且铜和镉的组合对小球藻氧化应激诱导具有强烈的协同作用。液相色谱串联质谱分析证实了氧化应激，该分析表明仅在添加铜的培养物中谷胱甘肽/氧化型谷胱甘肽（GSH/GSSG）比值大幅下降。有趣的是，我们观察到铜促进了小球藻对镉和铅的生物富集。在添加铜的培养物中缺乏植物螯合肽且细胞外聚合物（EPS）产量增加，这表明镉和铅的生物富集模式是通过游离金属吸附到藻类EPS上，而不是通过细胞内与植物螯合肽螯合。
