Background

Efficient microbe-assisted phytoremediation is urgently needed for coping with heavy metal-polluted environments.

Methods

In this study, a new strain of rhizobacteria from Cd-contaminated soil was screened, and its environmental adaptability, physiological characteristics, and effects on Cd phytoextraction were investigated. Furthermore, genomic sequencing and transcriptomic analysis were performed to explore the mechanisms underlying these functional characteristics.

Results

This strain, which was named Bacillus sp. LX1, was highly adaptable to Cd, pH, and temperature variations and exhibited typical plant growth-promoting characteristics. Inoculation with Bacillus sp. LX1 in rhizosphere improved Cd accumulation in mustard roots and shoots by 54.1% and 43.7%, respectively. These results can be attributed to increased plant growth, activated rhizospheric Cd bioavailability, and induced Cd transporter-encoding genes (e.g., HMA1, ZIP2, ZIP3, NRAMP3, and CAX2) in mustard roots. Integrated genomic and transcriptomic analyses provided molecular insights into its tolerance to Cd and enhancement of phytoextraction. The Bacillus sp. LX1 genome consists of a chromosome and a plasmid carrying a total of 5,934 genes with multiple functions. Under Cd (5 and 25 mg L⁻¹) stress, Bacillus sp. LX1 activated several important KEGG pathways, including quorum sensing, nucleotide excision repair, sulphur metabolism, and riboflavin metabolism, to resist Cd. Moreover, Cd regulated the synthesis of IAA, organic acids, siderophores, phosphatases, and extracellular polysaccharides, providing the material basis for Bacillus sp. LX1 to promote plant growth and increase soil Cd bioavailability.

Conclusion

This study greatly improves our understanding of the interactions among plants, rhizobacteria, and Cd.

中文翻译：

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新筛选的 Bacillus sp. LX1 菌株的基因组和转录组分析有助于了解其对 Cd 的耐受性和植物提取的增强

 背景

迫切需要高效的微生物辅助植物修复来应对重金属污染环境。

 方法

本研究从Cd污染土壤中筛选出一株新的根际细菌，研究其环境适应性、生理特性及其对Cd植物提取的影响。此外，进行了基因组测序和转录组学分析，以探索这些功能特征背后的机制。

 结果

该菌株被命名为 Bacillus sp. LX1，对 Cd、pH 值和温度变化具有高度适应性，并表现出典型的植物促生长特性。在根际接种 Bacillus sp. LX1 使芥菜根和芽中的 Cd 积累分别提高了 54.1% 和 43.7%。这些结果可归因于植物生长增加、根际 Cd 生物利用度激活以及芥菜根中诱导的 Cd 转运蛋白编码基因 （例如，HMA1、ZIP2、ZIP3、NRAMP3 和 CAX2）。综合基因组和转录组学分析为其对 Cd 的耐受性和植物提取增强的分子见解提供了分子见解。芽孢杆菌属 LX1 基因组由一条染色体和一个质粒组成，共携带 5,934 个具有多种功能的基因。在 Cd （5 和 25 mg ^L-1） 胁迫下，芽孢杆菌 LX1 激活了几种重要的 KEGG 途径，包括群体感应、核苷酸切除修复、硫代谢和核黄素代谢，以抵抗 Cd。此外，Cd 调节 IAA、有机酸、铁载体、磷酸酶和细胞外多糖的合成，为芽孢杆菌 LX1 促进植物生长和提高土壤 Cd 生物利用度提供物质基础。

 结论

这项研究极大地提高了我们对植物、根际细菌和 Cd 之间相互作用的理解。