Fig 8. Colony-spreading activities of S. aureus strains expressing different PSMs in different localization.

A. The S. aureus PSMα1-4/δ-toxin knockout strain was transformed with genes encoding PSMα1, PSMα2, PSMα3, PSMα4, PSMα1–4, and δ-toxin, which were placed under a strong or weak promoter. Overnight cultures of S. aureus Newman strain (Parent), the PSMα1-4/δ-toxin knockout strain transformed with an empty vector (pND50K), and the strains transformed with different PSM genes were spotted on soft agar plates and incubated at 37°C. The photograph was obtained at 9 h after incubation. B. The diameter of the giant colonies in A was measured. Data are means±standard errors from three independent experiments. Asterisks indicate Student’s t-test p value between PSMs expressing plasmid and pND50K less than 0.05.