Salunke Bipinchandra K, Sawant Shailesh S, Lee Sang-Ill, Kim Beom Soo
Department of Chemical Engineering, Chungbuk National University, Cheongju, Chungbuk, 362-763, Republic of Korea.
Appl Microbiol Biotechnol. 2015 Jul;99(13):5419-27. doi: 10.1007/s00253-015-6559-4. Epub 2015 Apr 7.
Microorganisms are one of the most attractive and simple sources for the synthesis of different types of metal nanoparticles. The synthesis of manganese dioxide nanoparticles (MnO2 NPs) by microorganisms from reducing potassium permanganate was investigated for the first time in the present study. The microbial supernatants of the bacterium Saccharophagus degradans ATCC 43961 (Sde 2-40) and of the yeast Saccharomyces cerevisiae showed positive reactions to the synthesis of MnO2 NPs by displaying a change of color in the permanganate solution from purple to yellow. KMnO4-specific peaks also disappeared and MnO2-specific peaks emerged at an absorption maximum of 365 nm in UV-visible spectrophotometry. The washed Sde 2-40 cells did not show any ability to synthesize MnO2 NPs. The medium and medium constituents of Sde 2-40 showed similar positive reactions as supernatants, which indicate the role of the Sde 2-40 medium constituents in the synthesis of MnO2 NPs. This suggests that microorganisms without nanoparticle synthesis ability can be misreported for their abilities to synthesize nanoparticles. S. cerevisiae washed cells showed an ability to synthesize MnO2 NPs. The strategies of keeping yeast cells in tea bags and dialysis membranes showed positive tests for the synthesis of MnO2 NPs. A Fourier transform-infrared spectroscopy study suggested roles for the proteins, alcoholic compounds, and cell walls of S. cerevisiae cells in the synthesis of MnO2 NPs. Electron-dispersive X-ray spectroscopy analyses confirmed the presence of Mn and O in the sample. X-ray photoelectron spectroscopy revealed characteristic binding energies for MnO2 NPs. Transmission electron microscopy micrographs revealed the presence of uniformly dispersed hexagonal- and spherical-shaped particles with an average size of 34.4 nm. The synthesis approach using yeast is possible by a simple reaction at low temperature without any need for catalysts, templates, or expensive and precise equipment. Therefore, this study will be useful for the easy, cost-effective, reliable, and eco-friendly production of nanomaterials.
微生物是合成不同类型金属纳米颗粒最具吸引力且最简单的来源之一。本研究首次对微生物从还原高锰酸钾合成二氧化锰纳米颗粒（MnO₂ NPs）进行了研究。食糖嗜降解菌嗜糖降解芽孢杆菌ATCC 43961（Sde 2 - 40）和酿酒酵母的微生物上清液对MnO₂ NPs的合成显示出阳性反应，高锰酸盐溶液的颜色从紫色变为黄色。在紫外可见分光光度法中，KMnO₄的特征峰也消失了，而在365 nm的吸收最大值处出现了MnO₂的特征峰。洗涤后的Sde 2 - 40细胞没有显示出合成MnO₂ NPs的任何能力。Sde 2 - 40的培养基及培养基成分显示出与上清液相似的阳性反应，这表明Sde 2 - 40培养基成分在MnO₂ NPs的合成中发挥了作用。这表明没有纳米颗粒合成能力的微生物可能会被错误报道具有合成纳米颗粒的能力。酿酒酵母洗涤后的细胞显示出合成MnO₂ NPs的能力。将酵母细胞置于茶包和透析膜中的策略对MnO₂ NPs的合成测试呈阳性。傅里叶变换红外光谱研究表明酿酒酵母细胞中的蛋白质、醇类化合物和细胞壁在MnO₂ NPs的合成中发挥了作用。能量散射X射线光谱分析证实样品中存在Mn和O。X射线光电子能谱揭示了MnO₂ NPs的特征结合能。透射电子显微镜照片显示存在平均尺寸为34.4 nm的均匀分散的六边形和球形颗粒。使用酵母的合成方法可以通过低温下的简单反应实现，无需任何催化剂、模板或昂贵精密的设备。因此，本研究将有助于简便、经济高效、可靠且环保地生产纳米材料。
