Culturing S. aureus and B. subtilis

S. aureus strains were grown in tryptic soy broth (TSB) at 30°C or 37°C with aeration, unless otherwise indicated. The medium was supplemented with erythromycin (5 μg/ml for chromosomal insertions and 10 μg/ml for plasmids), chloramphenicol (5 μg/ml for chromosomal insertions, 10 μg/ml for plasmid), spectinomycin (100 μg/ml), kanamycin and neomycin (25 μg/ml each), 5-bromo-4-chloro-3-indolyl ß-D-galactopyranoside (X-Gal, 250 μg/ml), or anhydrotetracycline (aTc, 100 ng/ml unless otherwise indicated). B. subtilis strains were derived from the prototrophic strain PY79 [40 (link)]. Cells were grown in Luria Broth (LB) or Casein Hydrolysate (CH) medium [41 ] at 37°C with aeration, unless otherwise indicated. The medium was supplemented with tetracycline (10 μg/ml), spectinomycin (100 μg/ml), kanamycin 10 μg/ml), chloramphenicol (5 μg/ml), xylose (0.5% w/v) or isopropyl ß-d-thiogalactopyranoside (IPTG, 0.5 mM). Lists of oligonucleotide primers, strains, plasmids, and descriptions of their construction can be found in Supplemental Material.