Department of Environmental Engineering, Kyunpook National University, 80 Daehak-ro, Buk-gu, Daegu 702-701, Republic of Korea.
J Hazard Mater. 2013 Sep 15;260:878-84. doi: 10.1016/j.jhazmat.2013.06.003. Epub 2013 Jun 7.
The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO₃ solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis.
在纳米技术领域，开发环保且可靠的纳米粒子合成工艺引起了广泛关注。在这项研究中，我们利用新分离的微生物极端芽孢杆菌（Exiguobacterium sp. KNU1）的胞外酶系统，将硝酸银溶液还原为银纳米粒子（AgNPs）。通过紫外可见光谱、傅里叶变换红外光谱和透射电子显微镜对胞外生物合成的 AgNPs 进行了表征。AgNPs 的尺寸约为 30nm（范围为 5-50nm），分散性好，呈球形。采用最低抑菌浓度法评估了 AgNPs 对不同革兰氏阴性菌和革兰氏阳性菌的抗菌效果。结果表明，AgNPs 对鼠伤寒沙门氏菌、铜绿假单胞菌、大肠杆菌和金黄色葡萄球菌具有合理的抗菌活性。所有测试的微生物都发生了形态变化。特别是，大肠杆菌在用 AgNPs 处理后表现出 DNA 片段化。最后，根据扫描电子显微镜和单细胞凝胶电泳的结果，提出了它们杀菌活性的机制。
