Table_2_Proteomic Perspective of Cadmium Tolerance in Providencia rettgeri Strain KDM3 and Its In-situ Bioremediation Potential in Rice Ecosystem.XLSX

In this study, a multi-metal-tolerant natural bacterial isolate Providencia rettgeri strain KDM3 from an industrial effluent in Mumbai, India, showed high cadmium (Cd) tolerance. Providencia rettgeri grew in the presence of more than 100 ppm (880 μM) Cd (LD50 = 100 ppm) and accumulated Cd intracellularly. Following Cd exposure, a comparative proteome analysis revealed molecular mechanisms underlying Cd tolerance. Among a total of 69 differentially expressed proteins (DEPs) in Cd-exposed cells, de novo induction of ahpCF operon proteins and L-cysteine/L-cystine shuttle protein FliY was observed, while Dps and superoxide dismutase proteins were overexpressed, indicating upregulation of a robust oxidative stress defense. ENTRA1, a membrane transporter showing homology to heavy metal transporter, was also induced de novo. In addition, the protein disaggregation chaperone ClpB, trigger factor, and protease HslU were also overexpressed. Notably, 46 proteins from the major functional category of energy metabolism were found to be downregulated. Furthermore, the addition of P. rettgeri to Cd-spiked soil resulted in a significant reduction in the Cd content [roots (11%), shoot (50%), and grains (46%)] of the rice plants. Cd bioaccumulation of P. rettgeri improved plant growth and grain yield. We conclude that P. rettgeri, a highly Cd-tolerant bacterium, is an ideal candidate for in-situ bioremediation of Cd-contaminated agricultural soils.

在本项研究中，从印度孟买某工业废水中分离得到的多金属耐受性天然细菌分离株Providencia rettgeri菌株KDM3，表现出了对镉（Cd）的高耐受性。Providencia rettgeri能够在超过100 ppm（880 μM）的Cd存在下生长（半数致死量LD50 = 100 ppm），并且能够将Cd积累于细胞内。在Cd暴露之后，通过比较蛋白质组学分析，揭示了镉耐受性背后的分子机制。在Cd暴露的细胞中，共观察到69种差异表达蛋白（DEPs），其中包括ahpCF操纵子蛋白以及L-半胱氨酸/L-胱氨酸穿梭蛋白FliY的从头诱导，同时Dps和超氧化物歧化酶蛋白的过表达表明了强效的氧化应激防御系统的上调。此外，与重金属转运蛋白同源的膜转运蛋白ENTRA1也被从头诱导。此外，蛋白质解聚伴侣ClpB、触发因子以及蛋白酶HslU的过表达也得到了证实。值得注意的是，从主要功能类别能量代谢的主要功能类别中发现了46种蛋白质表达下调。此外，将P. rettgeri添加到镉污染土壤中，显著降低了水稻植物中的镉含量[根系（11%）、茎（50%）和籽粒（46%）]。P. rettgeri的镉生物积累改善了植物生长和籽粒产量。我们得出结论，P. rettgeri，一种高度耐受Cd的细菌，是原位生物修复镉污染农业土壤的理想候选者。