Thirty microliters of purified phage suspension was adsorbed to carbon-coated copper grids (400-mesh) in a vacuum evaporator (JEE400, JEOL Ltd. Tokyo, Japan), allowed to air dry and then negatively stained with 2% phosphotungstic acid (pH 7.2). The excess solution was absorbed with filter paper, and samples were observed with a transmission electron microscope (JEM-1011, JEOL Ltd. Tokyo, Japan) operating at 80 kV (López-Cuevas et al., 2011 (link)).
Bacteriophage plaques formed on a TSA plate during the process of propagation (using dilutions that generated 15–30 plaques per plate) were analyzed according to the procedure described by Gallet, Kannoly & Wang (2011) (link) with minor modifications. Briefly, images of ten plates were captured by a supersensitive high-resolution 16-bit camera that was deeply cooled for faint image detection (Bio-Rad Laboratories), and the image of five plaques for each plate were displayed with the ImageJ software (developed at the National Institutes of Health, Bethesda, Maryland). The plates were then incubated for 18–24 h at 37 °C before plaque size determination. To calculate the surface area (expressed in square millimeters) corresponding to each pixel, a graticule of 1 mm2 was used as the reference scale for the simplified measurement of the lysis plaques. According to the analysis, each pixel corresponded to 0.5 mm2.
Bacteriophage plaques formed on a TSA plate during the process of propagation (using dilutions that generated 15–30 plaques per plate) were analyzed according to the procedure described by Gallet, Kannoly & Wang (2011) (link) with minor modifications. Briefly, images of ten plates were captured by a supersensitive high-resolution 16-bit camera that was deeply cooled for faint image detection (Bio-Rad Laboratories), and the image of five plaques for each plate were displayed with the ImageJ software (developed at the National Institutes of Health, Bethesda, Maryland). The plates were then incubated for 18–24 h at 37 °C before plaque size determination. To calculate the surface area (expressed in square millimeters) corresponding to each pixel, a graticule of 1 mm2 was used as the reference scale for the simplified measurement of the lysis plaques. According to the analysis, each pixel corresponded to 0.5 mm2.
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