Department of Civil and Environmental Engineering, University of Utah, UT, USA.
Department of Civil and Environmental Engineering, University of Utah, UT, USA.
Water Res. 2020 Aug 15;181:115900. doi: 10.1016/j.watres.2020.115900. Epub 2020 May 18.
Bacteriophages and engineered nano-material (AgNPS) interactions is a relatively unexplored area of research. To answer the fundamental question whether bacteriophage lytic growth cycle is affected by the presence of AgNPs, laboratory experiments were performed with phages of Klebsiella pneumoniae, Delftia tsuruhatensis, Salmonella typhimurium, and Shigella flexneri using silver nanoparticles (AgNPs) with coating materials. One-step growth curves of bacteriophages indicated that the presence of these nanoparticles, and the associated ions of silver, produced pronounced effects on the lytic infection of certain bacteriophages. Effects included 96% reductions in post-infection phage yield in terms of plaque forming units (PFUs) after phages were incubated with silver nanoparticles and 28%-43% reductions from the presence of Ag alone. However, when Klebsiella pneumonia phage KL and Salmonella typhimurium phage Det7 were exposed to silver nanoparticles coated with poly-N-vinyl-2 pyrrolidone (PVP), an increase in final phage yield by as much as 250% was observed compared with the same phage not incubated with nanoparticles. A proposed mechanism, observed by transmission electron microscopy and verified using synthetic biology by which the nanoparticle binding phenotype can be produced, is that the binding of metal nanomaterial to phage virions results in potentially inhibitory effects. This binding was found to be dependent on the presence of exposed positively charged C-terminal amino-acid residues on the phage capsid surface, implied at first by amino-acid sequence comparisons between capsid proteins of the different phages used in this study. This was then proven experimentally using targeted DNA editing methods to fuse positive charged amino-acid residues to the coat protein C-terminus of non-binding phage. This induced the AgNP binding phenotype, as observed by TEM, DLS size measurements, and growth curve data that show the mutant constructs to be functionally inhibited after exposure to AgNPs. This research sets up a first platform for further research in the unexplored area of phage and AgNP interactions and provides useful findings.
噬菌体和工程纳米材料（AgNPS）的相互作用是一个相对未被探索的研究领域。为了回答噬菌体裂解生长周期是否受到 AgNPs 存在影响的基本问题，我们使用具有涂层材料的银纳米粒子（AgNPs）对肺炎克雷伯菌、杜氏栖热菌、鼠伤寒沙门氏菌和福氏志贺菌的噬菌体进行了实验室实验。噬菌体一步生长曲线表明，这些纳米粒子及其相关的银离子对某些噬菌体的裂解感染产生了显著影响。这些影响包括噬菌体与银纳米粒子孵育后，噬菌斑形成单位（PFU）的感染后噬菌体产量减少了 96%，而单独存在 Ag 时则减少了 28%-43%。然而，当肺炎克雷伯菌噬菌体 KL 和鼠伤寒沙门氏菌噬菌体 Det7 暴露于涂有聚-N-乙烯基-2-吡咯烷酮（PVP）的银纳米粒子时，与未与纳米粒子孵育的相同噬菌体相比，最终噬菌体产量增加了高达 250%。通过透射电子显微镜观察到并通过合成生物学验证的一种假设机制表明，纳米粒子结合表型可以产生，即金属纳米材料与噬菌体病毒粒子的结合导致潜在的抑制作用。这种结合被发现依赖于噬菌体衣壳表面暴露的带正电荷的 C 末端氨基酸残基的存在，最初是通过本研究中使用的不同噬菌体的衣壳蛋白的氨基酸序列比较推断出来的。然后，通过使用靶向 DNA 编辑方法将带正电荷的氨基酸残基融合到非结合噬菌体的衣壳蛋白 C 末端，实验证明了这一点。这诱导了 AgNP 结合表型，如 TEM、DLS 尺寸测量和生长曲线数据所示，这些数据表明突变体构建体在暴露于 AgNPs 后功能受到抑制。这项研究为噬菌体和 AgNP 相互作用这一未探索领域的进一步研究奠定了第一个平台，并提供了有用的发现。
