State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Chemosphere. 2018 Oct;208:50-58. doi: 10.1016/j.chemosphere.2018.05.169. Epub 2018 May 29.
Heavy metal contamination is a significant environmental issue. Using bacteria for removal and reduction of heavy metals is an attractive alternative owing to its low-cost and eco-friendly properties. However, the mechanisms of resistance to and reduction of Ag(I), Pd(II), and Se(IV), especially in the same strain, remain unclear. Here, Pantoea sp. IMH was examed for its reduction of Ag(I), Pd(II), and Se(IV) to nanoparticles (NPs), and the molecular mechanism was investigated by transcriptome analysis. The results revealed that genes encoding binding, transport, catalytic activity, and metabolism were differentially expressed in cells exposed to Ag(I), Pd(II), and Se(IV). The same resistance mechanisms for all metals included multiple stress resistance protein BhsA and glutathione detoxification metabolism. However, zinc transport protein and sulfate metabolism played an important role in the resistance to cationic metals (Ag and Pd), while the oxalate transporter and arsenic resistance mechanisms were specifically involved in the resistance to and reduction of anion (SeO). In addition, Ag(I) was speculated to be reduced to AgNPs by glucose and cytochrome CpxP was involved in Pd(II) reduction. Our results provided new clues on the mechanisms of resistance to and reduction of Ag(I), Pd(II), and Se(IV).
重金属污染是一个严重的环境问题。利用细菌去除和减少重金属因其低成本和环保特性而成为一种有吸引力的选择。然而，对于同一菌株中 Ag(I)、Pd(II) 和 Se(IV) 的抗性和还原机制仍不清楚。在这里，研究了 Pantoea sp.IMH 将 Ag(I)、Pd(II) 和 Se(IV) 还原为纳米颗粒 (NPs) 的能力，并通过转录组分析研究了其分子机制。结果表明，暴露于 Ag(I)、Pd(II) 和 Se(IV) 时，细胞中编码结合、运输、催化活性和代谢的基因表达存在差异。所有金属的相同抗性机制包括多种应激抗性蛋白 BhsA 和谷胱甘肽解毒代谢。然而，锌转运蛋白和硫酸盐代谢在阳离子金属（Ag 和 Pd）的抗性中发挥重要作用，而草酸盐转运蛋白和砷抗性机制则专门参与阴离子（SeO）的抗性和还原。此外，推测葡萄糖将 Ag(I)还原为 AgNPs，细胞色素 CpxP 参与 Pd(II)的还原。我们的结果为 Ag(I)、Pd(II) 和 Se(IV) 的抗性和还原机制提供了新的线索。
