Establishment of Gold Standard for Electrolyzed Sodium Chloride Solution in Disinfectio

Electrolyzed saline as a recommended gold standard for the bactericidal activity of electrolyzed products was examined in this study. The electrolyzed saline showed stronger bactericidal activity against a Gram-positive bacterium (Staphylococcus aureus) than against a Gram-negative one (Pseudomonas aeruginosa). This difference in bactericidal activity was analyzed by measuring the cytoplasmic nitrate reductase activity and morphological changes in both bacteria. The difference in the manner of inactivation of nitrate reductase activity between the Gram-positive and Gramnegative bacteria indicates that the destruction of the cell wall differs between these bacteria. Morphological analysis showed that the outer layer of the Gram-positive bacterium degenerated with swelling and the periplasmic layer of the Gram-negative bacterium degenerated first. These findings indicate that the penetration of free chlorine differs between Gram-positive and Gram-negative bacteria, resulting in different susceptibilities to electrolyzed saline. Furthermore, the cause of the previously reported bleb formation in the Gram-negative bacterium, which was treated with electrolyzed products containing a low sodium chloride concentration, was shown to result from the osmotic pressure of the product. The usefulness of electrolyzed saline as gold standard for the evaluation of various electrolyzed products is discussed in this paper.