Fig. 3.

Haemin-induced stimulation of EsxA secretion in S. aureus is strain-specific. The indicated S. aureus strains were subcultured into TSB medium, or TSB medium supplemented with 4 µM haemin, as indicated, and grown aerobically until an OD₆₀₀ of 2 was reached. Samples were fractionated to give cells and supernatant (sn), and supernatant proteins were precipitated using TCA. For each gel, 4 µl of a cell culture adjusted to an OD₆₀₀ of 1 and 12 µl of culture supernatant were loaded. Western blots were probed with anti-EsxA or anti-TrxA (cytoplasmic control) antisera.