Bachrach U, Friedmann A
Appl Microbiol. 1971 Oct;22(4):706-15. doi: 10.1128/am.22.4.706-715.1971.
The efficiencies of the various methods used for phage concentration have been compared. The two-phase concentration method (with polyethylene glycol and dextran sulfate) gave maximal recoveries of infectivity for coliphages of the T-even and T-odd series and for ribonucleic acid phages and single-stranded deoxyribonucleic acid phages. Precipitation of phages by acid gave high yields when applied to T2 and T4 phages but not with T3 and T7 coliphages. Differential centrifugation was efficient when sedimented phages were gently dispersed before repeating the centrifugation cycle. The efficiencies of the various methods have also been confirmed by electron microscope studies, which also show that the two-phase concentration method gave rise to intact phages. Zone centrifugations in sucrose gradients (12.5 to 52.5%) indicated that coliphages of the T-even series sediment faster than T-odd coliphages; they may thus be separated from each other and from empty ghosts by centrifugation at 100,000 x g for 40 min. Equilibrium centrifugation in preformed cesium chloride gradients was also useful for phage concentration and purification. This study also deals with some optical properties of purified phages; optical cross sections and absorbance ratios (at 260 and 280 nm) of the various preparations are given.
已对用于噬菌体浓缩的各种方法的效率进行了比较。两相浓缩法（使用聚乙二醇和硫酸葡聚糖）对T偶数和T奇数系列的大肠杆菌噬菌体、核糖核酸噬菌体和单链脱氧核糖核酸噬菌体的感染力回收率最高。用酸沉淀噬菌体应用于T2和T4噬菌体时产量较高，但对T3和T7大肠杆菌噬菌体则不然。当沉淀的噬菌体在重复离心循环之前被轻轻分散时，差速离心是有效的。各种方法的效率也已通过电子显微镜研究得到证实，该研究还表明两相浓缩法产生完整的噬菌体。在蔗糖梯度（12.5%至52.5%）中进行区带离心表明，T偶数系列的大肠杆菌噬菌体比T奇数大肠杆菌噬菌体沉降得更快；因此，通过在100,000×g下离心40分钟，它们可以相互分离并与空壳分离。在预先形成的氯化铯梯度中进行平衡离心也有助于噬菌体的浓缩和纯化。本研究还涉及纯化噬菌体的一些光学性质；给出了各种制剂的光学横截面和吸光度比（在260和280nm处）。
