Figure 4. Microbicidal activity of nano-bubble ozone water (NBOW) that had been stored frozen for up to 1 year. The microbicidal activity of NBOW was first tested with E. coli W3110: A: Microbicidal activity of NBOW stored frozen for 1 month; B: Microbicidal activity of NBOW stored frozen for 3 months; C: Microbicidal activity of NBOW stored frozen for 1 year. The microbicidal activity of NBOW stored frozen for 1 year was also tested with M. smegmatis (D). The colony formation assay is described in Materials and Methods. The experiments were performed in triplicate and the values are presented as the means±SD.
