Figure 1: From left to right, examples of agar plates with grown colonies of Staphylococcus aureus: untreated control, very centred inhibition zone (Ar + 0.1% O2, 120 s exposure time in closed system, spatial-intermediate inhibition (Ar + 0.5% O2, 60 s exposure time in open system), un-centric overall reduction (Ar + 1% O2, 120 s exposure time in open system).