Etching of Bacterial Capsule and Cell Wall by Oxygen Plasma Afterglow

Sterilization of delicate materials by gaseous plasma represents an interesting task for plasma scientists. While sporulating bacteria are rather resistant to weak plasma treatments, some bacteria are destroyed even in an afterglow. A representative type of nonsporulating bacteria is Staphylococcus aureus. Such bacteria are destroyed by treatment with mostly neutral O atoms found in oxygen plasma afterglow. The degradation steps are followed by atomic force microscopy. The bacteria remain vital for about 2 min of treatment at the O flux of about 1.3 ×10²² m^-2·s^-1. The bacterial capsule is removed in about 2 min. Once the capsule is removed, degradation of the cell wall occurs, causing bacterial death.