南湖新闻网讯（通讯员：史凯祥）近日，我校生命科学技术学院、农业微生物学国家重点实验室王革娇教授领衔的环境微生物课题组在国际学术期刊Journal of Hazardous Materials发表了关于假单胞菌菌剂对重金属镉污染钝化的最新研究成果，阐明了假单胞菌菌剂通过新型镉结合蛋白去除镉的分子机制及菌剂对促进植物和土壤健康与降低镉含量的积极作用。
该课题组从镉污染农田土中分离鉴定了一株镉抗性细菌假单胞菌B7，该细菌培养后可完全去除溶液中的镉离子。采用差异蛋白质组学分析技术，镉离子能够显著激活一种碳酸酐酶的表达，命名为CadW。通过体内与体外实验证明了该蛋白能够提高细菌对镉离子的抗性，且能够与镉离子特异性结合从而将镉离子固定在细胞内部，其中123位的组氨酸为其保守的镉离子结合位点。将该微生物菌剂结合化学修复剂硅酸盐应用于镉污染白菜盆栽实验中，发现该微生物菌剂结合硅酸盐可以有效的钝化土壤中的镉，减少植物对镉离子的吸收，使白菜地上部分镉含量下降了34%，达到了安全可食用范围。植物酶活与土壤酶活分析，发现该混合菌剂可以缓解化学修复剂硅酸盐对植物和土壤的不利影响，具有增强植物与土壤健康的作用。
该课题组阐明了细菌中一种新型的镉钝化机制，从酶学角度探究了微生物对恢复土壤和植物健康的重要作用。其研究结果为理解微生物介导的环境中镉钝化迈出了重要的一步，为微生物菌剂在镉污染修复中的作用提供了重要理论价值和应用潜力。
华中农业大学生命科学技术学院武士娟博士为第一作者、王革娇教授与史凯祥副研究员为共同通讯作者，该工作得到国家自然科学基金的资助。
英文摘要：
In this study, we isolated a highly cadmium (Cd)-resistant bacterium, Pseudomonassp. 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.
全文链接：https://www.sciencedirect.com/science/article/pii/S0304389421028880
审核人：王革娇
