Antibacterial characteristics of magnesium oxide powder

The antibacterial activity of magnesium oxide (MgO) was studied. Inhibitory zones appeared around the MgO powder slurry put directly on nutrient agar plates seeded with Escherichia coli or Staphylococcus aureus. However, no z one was observed using a penicillin cup to avoid contact between the bacter ia and the MgO powder. Moreover, the supernatant solution of the MgO powder slurry and a MgCl2 solution containing Mg2+ at a concentration of the solu bility of MgO did not affect the growth of E. coli and S. aureus. Moreover, elevated shaking speed increased the death of E. coli in the slurry, indic ating that the contact frequency between bacterial cells and MgO powders af fected the antibacterial activity. It was considered that the contact betwe en MgO powder and bacteria was important for the occurrence of its antibact erial activity. Since the generation of active oxygen, such as O-2(-), from the MgO powder slurry was detected by chemiluminescence analysis, an inves tigation was carried out to determine whether active oxygen generated from MgO powder slurry was related to its antibacterial activity. The changes in the antibiotic sensitivity in E. coli treated by MgO powder agreed with th ose by active oxygen treatment. These results suggested that the active oxy gen generated from the MgO powder slurry was one of the primary factors in its antibacterial activity.