García-Gonzalo P, Pradas Del Real A E, Pirredda M, Gismera M J, Lobo M C, Pérez-Sanz A
Department of Agro-Environmental Research, IMIDRA, Alcalá de Henares 28800, Madrid, Spain.
Geochimie 4D Group, ISTerre, Université Grenoble I, 38041 Grenoble Cedex 9, France; ID21, ESRF-The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France.
Ecotoxicol Environ Saf. 2017 Oct;144:283-290. doi: 10.1016/j.ecoenv.2017.06.043. Epub 2017 Jun 20.
Understanding the metal behavior at the soil-root interface is of utmost significance for a successful implementation of phytoremediation. In this study, we investigated the differences in chromium (Cr) uptake, chemical changes in soil solution and the shifts in rhizosphere bacterial communities of two genotypes of Silene vulgaris (SV21, SV38) with different tolerance to Cr. A greenhouse experiment was performed in two soils that differed on pH and organic matter (OM) content. An industrial sludge with high content in Cr was used as pollution source. The soil solution in the rhizosphere was sample by Rhizon Soil Moisture Samplers. The total concentration of Cr reached the highest values in soil solution samplers from calcareous soils with poor contents in OM. Plants grown in this soil also increased the Cr uptake in roots of both genotypes, but the concentration was higher in genotype SV-38 than in SV21. The clustering analysis of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA fragments revealed major differences in bacterial community structure related to Cr pollution, followed by soil type and finally, plant genotype. Diversity indices based on DGGE profiles were the highest in alkaline soil, and between genotypes, values were significantly greater in SV38. Canonical correspondence analysis (CCA) showed that changes in bacterial community structure of rhizosphere were highly correlated with total Cr concentration and soil solution pH. The isolation and identification of S. vulgaris bacterial rhizosphere revealed a different composition according to soil type and plant genotype. Results suggested the potential role of Pseudomonas fluorescens on Cr mobilization and therefore, on enhanced metal bioavailability and may provide a starting point for further studies aimed at the combined use of tolerant plants and selected metal mobilizing rhizobacteria, in the microbial-assisted phytoremediation of Cr-polluted soils.
了解土壤-根系界面的金属行为对于成功实施植物修复至关重要。在本研究中，我们调查了两种对铬（Cr）耐受性不同的普通麦瓶草基因型（SV21、SV38）在铬吸收、土壤溶液化学变化以及根际细菌群落变化方面的差异。在两种pH值和有机质（OM）含量不同的土壤中进行了温室实验。使用高铬含量的工业污泥作为污染源。通过Rhizon土壤水分采样器采集根际土壤溶液。在OM含量低的石灰性土壤的土壤溶液采样器中，Cr的总浓度达到最高值。生长在这种土壤中的植物，两种基因型的根系对Cr的吸收也增加，但基因型SV - 38中的浓度高于SV21。16S rRNA片段的变性梯度凝胶电泳（DGGE）聚类分析表明，细菌群落结构的主要差异与Cr污染有关，其次是土壤类型，最后是植物基因型。基于DGGE图谱的多样性指数在碱性土壤中最高，在基因型之间，SV38的值显著更大。典范对应分析（CCA）表明，根际细菌群落结构的变化与总Cr浓度和土壤溶液pH高度相关。普通麦瓶草根际细菌的分离和鉴定显示，根据土壤类型和植物基因型，其组成不同。结果表明荧光假单胞菌在Cr活化以及因此在提高金属生物有效性方面的潜在作用，这可能为进一步研究旨在将耐性植物和选定的金属活化根际细菌联合用于Cr污染土壤的微生物辅助植物修复提供一个起点。
