Investigation of the Effective Concentration of Ozonated Water for Disinfection in the Presence of Protein Contaminants.

Ozonated water (OW) is presently used as a chemical disinfectant in many fields, due to its versatile antimicrobial properties. As ozone rapidly decomposes to oxygen, especially in the presence of organic matter, it is important to estimate the authentic antimicrobial activity of OW in the presence of contaminants. However, the effect of contaminants on the antimicrobial activity of OW has not been fully investigated. To address this, we evaluated the effect of protein contaminants on the antimicrobial activity of OW. The survival rate of each tested microorganism excluding Bacillus subtilis spores was reduced to less than 0.1%, when the microorganism suspension was exposed to 9.1 ppm of OW for 15 s in the presence of 0.0045% protein. Our study therefore suggests that approximately 10 ppm of OW can reduce the survival rates of almost all microorganisms in the presence of proteins.