从石斛中分离得到一株内生真菌DO-1，该菌株经鉴定为禾谷镰刀菌（Fusarium graminearum），其菌体在去离子水中浸泡后分泌的代谢产物与硝酸银作用后，能还原银离子产生具有抗菌作用的纳米银粒子。以440~450 nm范围内纳米银的特征性等离子吸收峰以及产物抑菌活性为指标，研究光照条件、温度以及pH条件对制备纳米银粒子的影响。黑暗条件和适当高温有助于纳米银粒子的生成及其抑菌活性的增强。随着pH的增加，纳米银特征性吸收峰不断增强，但抑菌活性呈现先增强再减弱的趋势，pH 7~8范围内得到的纳米银粒子的抑菌活性较高。调节F.graminearum DO-1菌体浸泡液的pH为7，与终浓度为1 mM的AgNO3溶液于80 ℃、黑暗条件下反应3 h，获得纳米银粒子，透射电镜分析显示制备的纳米银粒子为球形，直径范围2~50 nm。应用该内生真菌代谢产物制备具有抑菌功能的纳米银粒子，方法简单，条件温和，复合绿色生态的发展趋势。

DO-1, an endophytic fungus, was isolated from Dendrobium candidum and identified as Fusarium graminearum. The fungal biomass was immersed in distilled water, and the filtrate solution containing the metabolites was obtained. Silver nanoparticles (AgNPs) with antimicrobial activity were biosynthesized by mixing the filtrate solution with silver nitrate. The plasma absorption peak of UV-visible spectroscopy and antibacterial activity were measured to assess the effects of light, temperature, and pH on AgNP biosynthesis. Darkness and suitable high temperatures were beneficial to the biosynthesis and antibacterial activity of AgNPs and absorbance at 440~450 nm increased with increasing pH. The highest antibacterial activity was observed at pH 7~8, and it decreased at higher pH levels. AgNPs synthesized from F. graminearum DO-1 filtrate solution and 1 mM silver nitrate at pH 7 and 80 ℃ for 3 h in the darkness, were spherical shaped with the diameter range of 2~50 nm. The method of AgNPs biosynthesis used herein is simple, uses mild conditions, and is eco-friendly.

国家自然科学基金青年科学基金项目（31401534）；江苏省农业科学院基本科研业务专项项目（ZX（15）4044）