Department Biotechnology, Thapar Institute of Engineering and Technology, Patiala, India.
School of Physics and Materials Science, Thapar Institute of Engineering and Technology, Patiala, India.
IET Nanobiotechnol. 2021 Apr;15(2):236-245. doi: 10.1049/nbt2.12039. Epub 2021 Mar 30.
Release of metallic nanoparticles in soil poses a serious threat to the ecosystem as they can affect the soil properties and impose toxicity on soil microbes that are involved in the biogeochemical cycling. In this work, in vitro ecotoxicity of as-synthesised copper nanoparticles (CuNPs) on Bacillus subtilis (MTCC No. 441) and Pseudomonas fluorescens (MTCC No. 1749), which are commonly present in soil was investigated. Three sets of colloidal CuNPs with identical physical properties were synthesised by chemical reduction method with per batch yield of 0.2, 0.3 and 0.4 gm. Toxicity of CuNPs against these soil bacteria was investigated by MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration), cytoplasmic leakage and ROS (reactive oxygen species) assay. MIC of CuNPs were in the range of 35-60 µg/ml and 35-55 µg/ml for B. subtilis and P. fluorescens respectively, while their MBC ranged from 40-70 µg/ml and 40-60 µg/ml respectively. MIC and MBC tests reveal that Gram-negative P. fluorescens was more sensitive to CuNPs as compared to Gram positive B. subtilis mainly due to the differences in their cell wall structure and composition. CuNPs with smaller hydrodynamic size (11.34 nm) were highly toxic as revealed by MIC, MBC tests, cytoplasmic leakage and ROS assays, which may be due to the higher active surface area of CuNPs and greater membrane penetration. Leakage of cytoplasmic components and generation of extra-cellular oxidative stress by reactive oxygen species (ROS) causes cell death. The present study realizes in gauging the negative impact of inadvertent release of nanoparticles in the environment, however, in situ experiments to know its overall impact on soil health and soil microflora can help in finding solution to combat ecotoxicity of nanoparticles.
在土壤中释放金属纳米颗粒对生态系统构成了严重威胁，因为它们会影响土壤特性，并对参与生物地球化学循环的土壤微生物造成毒性。在这项工作中，研究了在土壤中普遍存在的枯草芽孢杆菌（MTCC No.441）和荧光假单胞菌（MTCC No.1749）的合成铜纳米颗粒（CuNPs）的体外生态毒性。通过化学还原法以每批 0.2、0.3 和 0.4 克的产量合成了三组具有相同物理性质的胶体 CuNPs。通过 MIC（最小抑菌浓度）、MBC（最小杀菌浓度）、细胞质渗漏和 ROS（活性氧）测定法研究了 CuNPs 对这些土壤细菌的毒性。CuNPs 对枯草芽孢杆菌和荧光假单胞菌的 MIC 分别为 35-60μg/ml 和 35-55μg/ml，而其 MBC 分别为 40-70μg/ml 和 40-60μg/ml。MIC 和 MBC 测试表明，革兰氏阴性荧光假单胞菌比革兰氏阳性枯草芽孢杆菌对 CuNPs 更为敏感，这主要是由于它们细胞壁结构和组成的差异。水动力尺寸较小（11.34nm）的 CuNPs 由于 MIC、MBC 测试、细胞质渗漏和 ROS 测定显示出更高的毒性，这可能是由于 CuNPs 的更高活性表面积和更大的膜穿透性。细胞质成分的泄漏和活性氧物质（ROS）引起的细胞外氧化应激导致细胞死亡。本研究实现了衡量纳米颗粒意外释放对环境的负面影响，然而，进行原位实验以了解其对土壤健康和土壤微生物群落的整体影响有助于找到应对纳米颗粒生态毒性的解决方案。
