FIG. 2.

Comparison of liquid cultures of wild-type (wt) and ΔsigB mutant (mut) forms of S. aureus Newman. (A) Sedimentation of a culture grown overnight is shown after 1 h without shaking. Overnight cultures were also analyzed by light microscope (×1,000 magnification) (B) or by electron microscope (C). In both cases, aggregation of the cells was visible. The arrows indicate areas of close contact between cells.