Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, 202002, India.
Department of Botany and Microbiology, College of Science, King Saud University, P.O. 2455, Riyadh, 11451, Saudi Arabia.
Environ Pollut. 2021 Jan 15;269:116218. doi: 10.1016/j.envpol.2020.116218. Epub 2020 Dec 2.
The current study for the first time demonstrates the interference of a free-living, N-fixing, and nanoparticle (NP) tolerant Azotobacter salinestris strain ASM recovered from metal-polluted soil with tomato plant-metal oxide NPs (ZnO, CuO, AlO and TiO) interactions in a sandy clay loam soil system with bulk materials as control. Tomato plants were grown till full maturity in soils amended with 20-2000 mg kg of each metal-oxide NP with and without seed biopriming and root-inoculation of A. salinestris. A. salinestris was found metabolically active, producing considerably high amounts of bioactive indole-3-acetic-acid, morphologically unaffected, and with low alteration of cell membrane permeability under 125-1500 μgml of NPs. However, ZnO-NPs slightly alter bacterial membrane permeability. Besides, A. salinestris secreted significantly higher amounts of extracellular polymeric substance (EPS) even under NP exposure, which could entrap the NPs and form metal-EPS complex as revealed and quantified by SEM-EDX. NPs were also found adsorbed on bacterial biomass. EPS stabilized the NPs and provided negative zeta potential to NPs. Following soil application, A. salinestris improved the plant performance and augmented the yield of tomato fruits and lycopene content even in NPs stressed soils. Interestingly, A. salinestris inoculation enhanced photosynthetic pigment formation, flower attributes, plant and fruit biomass, and reduced proline level. Bacterial inoculation also reduced the NP's uptake and accumulation significantly in vegetative organs and fruits. The organ wise order of NP's internalization was roots > shoots > fruits. Conclusively, A. salinestris inoculation could be an alternative to increase the production of tomato in metal-oxide NPs contaminated soils.
本研究首次证明了一种从金属污染土壤中回收的自生固氮和耐受纳米颗粒（NP）的盐单胞菌（Azotobacter salinestris）菌株 ASM 与番茄植物-金属氧化物 NPs（ZnO、CuO、AlO 和 TiO）在砂壤土系统中的相互作用，其中 bulk materials 作为对照。在添加了 20-2000 mg kg 各金属氧化物 NP 的土壤中种植番茄植物，直至完全成熟，同时进行种子生物引发和根接种盐单胞菌 ASM。结果发现，盐单胞菌 ASM 代谢活跃，产生大量生物活性吲哚-3-乙酸，形态不受影响，细胞膜通透性变化较小，在 125-1500 μg ml 的 NPs 下。然而，ZnO-NPs 会轻微改变细菌细胞膜通透性。此外，盐单胞菌 ASM 甚至在 NP 暴露下分泌出更高量的胞外聚合物物质（EPS），这可以通过 SEM-EDX 揭示和量化，从而捕获 NPs 并形成金属-EPS 复合物。还发现 NPs 吸附在细菌生物量上。EPS 稳定了 NPs，并为 NPs 提供了负的 ζ 电位。土壤应用后，盐单胞菌 ASM 改善了植物性能，增加了番茄果实的产量和番茄红素含量，即使在 NP 胁迫土壤中也是如此。有趣的是，盐单胞菌接种增强了光合色素的形成、花属性、植物和果实生物量，并降低了脯氨酸水平。细菌接种还显著减少了 NP 在营养器官和果实中的吸收和积累。NP 内化的器官顺序为根>茎>果实。总之，盐单胞菌接种可以作为增加金属氧化物 NP 污染土壤中番茄产量的替代方法。
