Strains and growth conditions
Staphylococcal strains used in this work are listed in Supp. Table S1. All strains were grown in Tryptic Soy Broth, 37°C, 180 rpm. For strains carrying resistance genes, antibiotics (10 µg/ml) used only in precultures. Bacteria from an overnight culture were diluted to an initial optical density OD600 = 0.2 and grown for 2 h. For S. epidermidis strain carrying an AHT-inducible plasmid (pCG817), AHT-induction (0.1 µg/ml) was started in day cultures and maintained during the whole experiment until t0, t3 or t24.
To check if bacterial growth is not decreased by bafilomycinA1 treatment, bacteria from overnight culture were diluted to an initial optical density OD600 = 0.05 in a 96-flat-bottom-plate with or without BafilomycinA1 (0.1 µM). Absorbance were measured with a wavelength of 600 nm for 12 h in a Tecan-reader.
For pH dependent growth, bacteria from an overnight culture were diluted to an initial optical density OD600 = 0.05 in LB-medium with pH7 or pH5 in a 96-flat-bottom-plate (Greiner). Absorbance were measured with a wavelength of 600 nm for 12 h in a Tecan-reader.