Fig. 1. High concentrations of copper inhibit the growth of S. aureus. Wild type S. aureus SH1000 were inoculated to a starting OD_595nm of 0.03 into (A) two types of rich media, tryptic soy broth (TSB – black bars) or LB (grey bars), or (B) two types of minimal media, glucose-containing chemically defined medium (CDM – black bars) or Tris-minimal (TM) medium lacking glucose (grey bars), each supplemented with increasing concentrations of CuSO₄. The cultures were incubated for 5 h at 37 °C with orbital shaking (180 rpm), and the final OD_595nm values were recorded. Growth is inhibited by high levels of copper in all media, but this toxicity effect is greatest in the minimal media. The symbols represent statistical significance based on a Student's t-test, where ns = not significant, * = p < 0.05, ** = p < 0.005, and *** = p < 0.0005.