Department of Bioprocess Development, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications, Alexandria 21934, Egypt.
J Microbiol Biotechnol. 2014 Apr;24(4):453-64. doi: 10.4014/jmb.1310.10095.
The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).
本研究聚焦于利用先前鉴定为新型埃及链霉菌 NEAE 102 的无细胞上清液体外生物合成杀菌银纳米粒子 (AgNPs)。埃及链霉菌 NEAE 102 合成银纳米粒子的速度非常快，所需时间比以前发表的菌株要少得多。通过紫外-可见光谱法，所产生的粒子在 400nm 处显示出单一的表面等离子体共振峰，证实了 AgNPs 的存在。响应面法被选来评估四个工艺变量（AgNO3 浓度、孵育时间、pH 值和接种量）对埃及链霉菌 NEAE 102 合成银纳米粒子的影响。结果的统计分析表明，孵育时间、初始 pH 值和接种量的线性和二次效应对埃及链霉菌 NEAE 102 合成银纳米粒子有显著影响（p<0.05）。在运行 5 和 14 号条件下，AgNO3 的最大银纳米粒子生物合成量（2.5 OD，在 400nm 处）达到 1mM（1-1.5%（v/v））、孵育时间（72-96h）、初始 pH（9-10）和接种量（2-4%（v/v））。与未优化条件相比，AgNPs 生物合成量总体增加了 4 倍。通过紫外-可见分光光度计和傅里叶变换红外光谱分析，以及抗菌性能对生物合成的银纳米粒子进行了表征。所合成的 AgNPs 显著抑制了重要的医学致病革兰氏阳性（金黄色葡萄球菌）和革兰氏阴性菌（铜绿假单胞菌）和酵母（白色念珠菌）的生长。
