Morphological Analysis of Phage CUB19 by TEM

The morphology of CUB19 was detected by transmission electron microscopy (TEM) using a Zeiss EM 906 microscope (Carl Zeiss Microscopy Deutschland GmbH, Oberkochen, Germany) and negative staining as in a previous study [14 (link)]. Shortly, 15 µL of phage solution was dropped onto Parafilm and transferred onto a carbon-coated and glow discharged (Leica MED 020, Leica Microsystems, Wetzlar, Germany) Ni-mesh grid (G2430N; Plano GmbH, Wetzlar, Germany), and left to adsorb for 10–15 min at room temperature. After washing the grids three times with Aquadest, they were treated with 1% aqueous uranyl acetate (SERVA Electrophoresis GmbH, Heidelberg, Germany) for 20 s for negative staining. Grids were air dried and then imaged by TEM at a voltage of 80 kV. Phage size was measured using the image processing program ImageJ.JS 1.53 m [15 ].