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.

在这项研究中，我们分离了一种高度抗镉 (Cd) 的细菌Pseudomonas sp。B7，从培养基中固定 100% Cd(II)。用 Cd(II) 培养菌株 B7 导致官能团的变化，介导细胞外 Cd(II) 吸附。蛋白质组学显示碳酸酐酶 CadW 被 Cd(II) 上调。CadW 在大肠杆菌中的表达赋予对 Cd(II) 的抗性并增加细胞内 Cd(II) 的积累。荧光检测表明 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) 螯合。使用菌株 B7 和硅酸盐 [Si(IV)] 进行大白菜盆栽实验。与对照相比，B7、Si(IV)和B7+Si( IV) 分别处理。单独施用 Si(IV) 可使土壤中的叶绿素含量降低 20.8%，芳基硫酸酯酶活性降低 33.9%，丙二醛活性提高 15.0%。菌株 B7 的应用减轻了 Si(IV) 对植物和土壤酶的负面影响。