State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
J Hazard Mater. 2022 Mar 5;425:127919. doi: 10.1016/j.jhazmat.2021.127919. Epub 2021 Nov 27.
In this study, we isolated a highly cadmium (Cd)-resistant bacterium, Pseudomonas sp. B7, which immobilized 100% Cd(II) from medium. Culturing strain B7 with Cd(II) led to the change of functional groups, mediating extracellular Cd(II) adsorption. Proteomics showed that a carbonic anhydrase, CadW, was upregulated with Cd(II). CadW expression in Escherichia coli conferred resistance to Cd(II) and increased intracellular Cd(II) accumulation. Fluorescence assays demonstrated that CadW binds Cd(II) and the His123 residue affected Cd(II) binding activity, indicating that CadW participates in intracellular Cd(II) sequestration. Chinese cabbage pot experiments were performed using strain B7 and silicate [Si(IV)]. Compared with the control, Cd content in aboveground parts significantly decreased by 21.3%, 29.4% and 32.9%, and nonbioavailable Cd in soil significantly increased by 129.4%, 45.0% and 148.7% in B7, Si(IV) and B7 +Si(IV) treatments, respectively. The application of Si(IV) alone reduced chlorophyll content by 20.8% and arylsulfatase activity in soil by 33.9%, and increased malonaldehyde activity by 15.0%. The application of strain B7 alleviated the negative effect of Si(IV) on plant and soil enzymes. Overall, application of Si(IV) is most conducive to the decreased Cd accumulation in plant, and strain B7 is beneficial to maintaining soil and plant health.
在本研究中，我们分离到一株高度耐镉（Cd）的细菌，假单胞菌 B7，该菌能从培养基中固定 100%的 Cd(II)。用 Cd(II)培养菌株 B7 会导致功能基团发生变化，从而介导细胞外 Cd(II)的吸附。蛋白质组学表明，碳酸酐酶 CadW 被上调与 Cd(II)有关。在大肠杆菌中表达 CadW 赋予其对 Cd(II)的抗性，并增加细胞内 Cd(II)的积累。荧光测定表明 CadW 与 Cd(II)结合，His123 残基影响 Cd(II)结合活性，表明 CadW 参与细胞内 Cd(II)的螯合。采用菌株 B7 和硅酸钠[Si(IV)]进行小白菜盆栽实验。与对照相比，B7、Si(IV)和 B7+Si(IV)处理分别使地上部分 Cd 含量显著降低 21.3%、29.4%和 32.9%，土壤中非生物有效态 Cd 含量分别显著增加 129.4%、45.0%和 148.7%。单独施用 Si(IV)会使叶绿素含量降低 20.8%，土壤中芳基硫酸酯酶活性降低 33.9%，丙二醛活性增加 15.0%。菌株 B7 的应用缓解了 Si(IV)对植物和土壤酶的负面影响。总的来说，施用 Si(IV)最有利于减少植物对 Cd 的积累，而菌株 B7 有利于维持土壤和植物健康。
