2.5.1 Medium, strain and culture conditions
This study used S. aureus (ATCC 6538) which was stored at –80 ℃. The strain was precultured in 20 mL of 25 g/L Luria–Bertani (LB) medium at 37 ℃ for 12 h. The initial inoculation concentration was set at OD600 = 0.05. The suspension culture medium (5 mL) was a mixture of LB (25 g/L) and glucose (5 g/L). Different concentrations of indoxyl were added. Test tubes were incubated (200 rpm) at 37 ℃ for 10 h.