該課題組從鎘污染農(nóng)田土中分離鑒定了一株鎘抗性細(xì)菌假單胞菌B7，該細(xì)菌培養(yǎng)后可完全去除溶液中的鎘離子。采用差異蛋白質(zhì)組學(xué)分析技術(shù)，鎘離子能夠顯著激活一種碳酸酐酶的表達(dá)，命名為CadW。通過體內(nèi)與體外實(shí)驗(yàn)證明了該蛋白能夠提高細(xì)菌對(duì)鎘離子的抗性，且能夠與鎘離子特異性結(jié)合從而將鎘離子固定在細(xì)胞內(nèi)部，其中123位的組氨酸為其保守的鎘離子結(jié)合位點(diǎn)。將該微生物菌劑結(jié)合化學(xué)修復(fù)劑硅酸鹽應(yīng)用于鎘污染白菜盆栽實(shí)驗(yàn)中，發(fā)現(xiàn)該微生物菌劑結(jié)合硅酸鹽可以有效的鈍化土壤中的鎘，減少植物對(duì)鎘離子的吸收，使白菜地上部分鎘含量下降了34%，達(dá)到了安全可食用范圍。植物酶活與土壤酶活分析，發(fā)現(xiàn)該混合菌劑可以緩解化學(xué)修復(fù)劑硅酸鹽對(duì)植物和土壤的不利影響，具有增強(qiáng)植物與土壤健康的作用。

 

　　該課題組闡明了細(xì)菌中一種新型的鎘鈍化機(jī)制，從酶學(xué)角度探究了微生物對(duì)恢復(fù)土壤和植物健康的重要作用。其研究結(jié)果為理解微生物介導(dǎo)的環(huán)境中鎘鈍化邁出了重要的一步，為微生物菌劑在鎘污染修復(fù)中的作用提供了重要理論價(jià)值和應(yīng)用潛力。

 

　　華中農(nóng)業(yè)大學(xué)生命科學(xué)技術(shù)學(xué)院武士娟博士為第一作者、王革嬌教授與史凱祥副研究員為共同通訊作者，該工作得到國家自然科學(xué)基金的資助。

 

　　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.

 

　　全文鏈接：https://www.sciencedirect.com/science/article/pii/S0304389421028880