Electron microscopy 电子显微镜
The size and morphology of phages were examined with transmission electron microscopy (TEM) using a JEOL JEM1400 (JEOL USA Inc., Peabody, MA, USA) at 80 kV. Briefly, 5µL of diluted phage solution were placed onto carbon-coated copper grids (FCF-200-Cu, Electron Microscopy Sciences, Hatfield, PA, USA). After 3 min, the grid was dipped into a ddH2O droplet and then 1% uranyl acetate for staining was added to the sample and allowed to dry for 15 min before performing microscopy.
使用 JEOL JEM1400(JEOL USA Inc.,Peabody, MA, USA)透射电子显微镜(TEM)在 80 kV 下观察噬菌体的大小和形态。简单地说,将 5µL 稀释噬菌体溶液置于碳涂层铜栅(FCF-200-Cu,Electron Microscopy Sciences, Hatfield, PA, USA)上。3 分钟后,将栅格浸入 ddH 2 O 液滴中,然后滴入 1%的尿素。O 液滴中,然后向样品中加入 1%的醋酸铀酰进行染色,待其干燥 15 分钟后再进行显微镜观察。
Phage stability assays 噬菌体稳定性检测
Temperature, pH (buffer adjusted with NaOH and HCl to pH 1–14), serum/plasma, saline, and long-term stability assays were performed with PAO1 at 4 °C except forthe thermal stability assays. Serum was obtained from a healthy donor and single-donor plasma was obtained from Innovative Research (Novi, MI, USA).
温度、pH 值(缓冲液用 NaOH 和 HCl 调节至 pH 1-14)、血清/血浆、生理盐水和长期稳定性检测均在 4 °C 下用 PAO1 进行,热稳定性检测除外。血清取自健康供体,单供体血浆取自 Innovative Research 公司(美国密歇根州诺维市)。
Bacterial growth kinetics
细菌生长动力学
Fresh stationary phase cultures were diluted to an optical density at wavelength 600 nm (OD600) equal to 0.1 in LB and cultured in an automated spectrophotometer (BioTek Epoch2 microplate reader, Agilent, Santa Clara, CA, USA) for 20 h with shaking at 37 °C. Measurements at OD600 were obtained every 5 min. Growth curve data were fit to a logarithmic curve using the R package GrowthCurver, and growth parameters were averaged over all replicates41.
将新鲜的静止期培养物在 LB 中稀释至波长 600 纳米处的光密度(OD 600 )等于 0.1,然后在自动分光光度计(BioTek Epoch2 微孔板阅读器,Agilent, Santa Clara, CA, USA)中培养 20 小时,37 °C,振荡。每 5 分钟测量一次 OD 600 。生长曲线数据使用 R 软件包 GrowthCurver 拟合成对数曲线,生长参数取所有重复 41 的平均值。
One step growth curve and adsorption assay
一步生长曲线和吸附试验
Three vials of 4.5 mL fresh PAO1 cultures and 0.5 mL phage were cultured with shaking (250 rpm, 37 °C) at indicated MOIs (PFU/mL)/(CFU/mL). At each timepoint, 100 µL of the phage-bacteria suspensions were diluted 1:10 eight times and all dilutions were spotted on PAO1 within soft agar. Adsorption assays followed the same procedure as one step growth curves aside from centrifugation of 100 µL of the phage-bacteria suspension at each timepoint at 12,000rcf (relative centrifugal force) for 5 min and diluting the supernatant to assess the free phages in the suspension.
三瓶 4.5 mL 新鲜 PAO1 培养物和 0.5 mL 噬菌体在指定 MOI(PFU/mL)/(CFU/mL)条件下振荡培养(250 rpm,37 °C)。在每个时间点,将 100 µL 的噬菌体-细菌悬浮液按 1:10 稀释八倍,然后将所有稀释液点在软琼脂中的 PAO1 上。除了在每个时间点将 100 µL 的噬菌体-细菌悬浮液以 12,000rcf (相对离心力)离心 5 分钟并稀释上清液以评估悬浮液中的游离噬菌体外,吸附测定的步骤与一步生长曲线相同。