One-Step Growth Curve

A one-step growth curve analysis was performed as described previously (Lu et al., 2003). Briefly, phage was mixed with the S. aureus host strain in the early exponential growth phase (5.6 × 10⁷ colony-forming units/mL) at an MOI of 0.1. After incubation at 37°C for 5 min to enable adsorption of the phage, it was centrifuged at 10,000 × g for 5 min. The pellet containing infected cells was resuspended in 50 mL of fresh TSB and incubated at 37°C with shaking at 220 rpm. Samples were collected every 10 min for 6 h. Subsequently, each sample was centrifuged at 16,000 × g for 1 min, and the sample titer was assessed by spotting tenfold serially diluted supernatants on a double-layer agar plate. Latent period and burst size were analyzed according to the resulting titer. The latent period of phage was calculated by measuring the interval of time between phage infection and the initial burst of phage titers. The burst size of phage was calculated by dividing the phage titers at postburst plateau phase by the initial phage titers.