Zhang Linlin, Li Na, Xiao Xinfeng, Guo Linke, Li Wenfang, Li Yanjun, Ling Fei
College of Safety and Environment Engineering, Shandong University of Science and Technology, Qingdao, 266510, China.
World J Microbiol Biotechnol. 2025 May 5;41(5):164. doi: 10.1007/s11274-025-04330-w.
Heavy metal contamination, particularly mercury (Hg), represents a substantial threat to aquatic ecosystems and primary producers. In this study, we systematically examined the impacts of varying concentrations of Hg(II) on Isochrysis galbana in terms of growth, chlorophyll a content, soluble protein levels, and ultrastructure. Results demonstrated that when Hg(II) concentrations exceeded 0.2 mg/L, the growth of I. galbana was significantly inhibited. At Hg(II) concentrations below 0.2 mg/L, the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were enhanced. Further analyses revealed that Hg(II) was detoxified through binding to functional groups on the cell surface and to macromolecular compounds within the cell via hydrogen and ionic bonds. X-ray photoelectron spectroscopy measurements indicated the possible existence of accumulated mercury in the forms of Hg₃(PO₄)₂ or HgO. Notably, morphological analysis disclosed chromatin agglutination, cell fragmentation, and other typical apoptotic features in I. galbana cells following exposure to Hg(II). Transcriptome analysis further showed that Hg(II) significantly disrupted the expression of genes involved in photosynthesis, tricarboxylic acid (TCA) cycle, and DNA replication pathways, which consequently affected the growth and metabolism of I. galbana, ultimately leading to growth inhibition. Collectively, these findings offer novel insights into the biochemical and physiological response mechanisms by which Hg impacts aquatic primary producers.
重金属污染，尤其是汞（Hg），对水生生态系统和初级生产者构成了重大威胁。在本研究中，我们系统地研究了不同浓度的Hg(II)对球等鞭金藻在生长、叶绿素a含量、可溶性蛋白质水平和超微结构方面的影响。结果表明，当Hg(II)浓度超过0.2 mg/L时，球等鞭金藻的生长受到显著抑制。在Hg(II)浓度低于0.2 mg/L时，超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）等抗氧化酶的活性增强。进一步分析表明，Hg(II)通过与细胞表面的官能团以及细胞内的大分子化合物通过氢键和离子键结合而被解毒。X射线光电子能谱测量表明可能存在以Hg₃(PO₄)₂或HgO形式积累的汞。值得注意的是，形态学分析揭示了球等鞭金藻细胞在暴露于Hg(II)后出现染色质凝集、细胞破碎和其他典型的凋亡特征。转录组分析进一步表明，Hg(II)显著破坏了参与光合作用、三羧酸（TCA）循环和DNA复制途径的基因的表达，从而影响了球等鞭金藻的生长和代谢，最终导致生长抑制。总的来说，这些发现为汞影响水生初级生产者的生化和生理反应机制提供了新的见解。
