Degradation of Staphylococcus aureus bacteria by neutral oxygen atoms

The degradation of Staphylococcus aureus bacteria during treatment with neutral oxygen atoms was monitored by scanning electron microscopy. Experiments were performed in an afterglow chamber made from borosilicate glass. The source of oxygen atoms was remote inductively coupled radiofrequency oxygen plasma. The density of atoms at the samples was 8×1020 m−3. The treatment was performed at room temperature. The first effect was the removal of dried capsule. Capsule on exposed parts of bacteria was removed after receiving the dose of 6×1023 at./m2, while the parts of capsule filling the gaps between bacteria were removed after receiving the dose of 2.4×1024 m−2. After removing the capsule, degradation continued as etching of bacterial cell wall. The etching was rather nonuniform as holes with diameter of several 10 nm were observed. The cell wall was removed after receiving the dose of about 7×1024 m−2. The etching probabilities were about 2×10−5 for the capsule and 2×10−6 for the cell wall. The results were explained by different compositions of capsule and the cell wall.