镉铜复合污染土壤中南方红豆杉的重金属提取效果及根际细菌群落特征

为明确复合重金属污染土壤对南方红豆杉价值的影响,以高经济价值植物南方红豆杉(Taxus wallichiana var. mairei)为研究材料,在田间Cd/Cu复合污染土壤上开展大田试验,采用高通量测序和ICP-MS分析技术,研究了复合污染土壤条件下南方红豆杉根际细菌群落特征和特异细菌群落结构,测定了南方红豆杉各部位重金属的含量。结果表明:南方红豆杉的种植显著降低了根际土壤的细菌α-多样性,改变了根际土壤细菌群落结构,与非根际土壤相比,南方红豆杉的根际土壤细菌群落结构组成明显不同,南方红豆杉根际Alphaproteobacteria纲(Sphingobium、Kaistobacter)、Betaproteobacteria纲(Oxalobacteraceae、Comamonadaceae)、Gammaproteobacteria纲(Acinetobacter)和Bacteroidetes门(Sphingobacteriaceae)尤为丰富。PICRUSt分析表明南方红豆杉根际中有着丰度更高的与转运蛋白、氨基酸代谢、磷酸盐代谢相关的预测功能基因。与非根际土壤相比,南方红豆杉根际土壤的Cd、Cu含量分别显著降低18.8%和55.1%;且南方红豆杉高价值部位重金属Cd和Cu含量偏低,分别是根部的24.8%和30.7%。研究表明,南方红豆杉根际形成了特异细菌群落结构,其对于根际土壤重金属Cd、Cu有良好的萃取效果。

Phytoextraction of heavy metals and characteristics of the rhizosphere bacterial community of Taxus wallichiana var. mairei on multi-metal (cadmium and copper) -contaminated soil

The economic utilization of heavy-metal-contaminated soil is an important research topic in the field of land resource utilization. We conducted a field experiment on cadmium (Cd) and copper (Cu) soil to investigate the influence of multi-contaminated conditions on the economic value of the soil. 16S rRNA gene sequencing combined with inductively coupled plasma-mass spectrometry were applied to analyze the rhizosphere bacterial community structure and concentrations of Cd/Cu in different tissues of Taxus wallichiana var. mairei under multi-metal (Cd, Cu) stress. Cultivation of T. wallichiana var. mairei significantly changed the soil bacterial diversity, in which bacterial alpha diversity was significantly reduced in the rhizosphere. There was an obvious difference in the bacterial community structure between the rhizosphere and bulk compartment. Several key taxa from the phyla Alphaproteobacteria (Sphingobium and Kaistobacter), Betaproteobacteria (Oxalobacteraceae and Comamonadaceae), Gammaproteobacteria (Acinetobacter), and Bacteroidetes (Sphingobacteriaceae) were especially abundant in the rhizosphere of T. wallichiana var. mairei. PICRUSt analysis predicted a high relative abundance of functional genes related to transporters, amino metabolism, and phosphate metabolism in the rhizosphere of T. wallichiana var. mairei. The total and available concentrations of Cd and Cu in the rhizosphere were significantly reduced by 18.8% and 55.1%, respectively, after planting T. wallichiana var. mairei. Collectively, these results demonstrate that a specific bacterial community structure is formed in the rhizosphere of T. wallichiana var. mairei, which has a beneficial effect on the phytoextraction of Cd and Cu in the rhizosphere soils.