The Respiratory Chain of Bacteria is a Target of the Disinfectant MA-T

The importance of preventing infectious disease for public health continues to increase, and effective disinfectants are needed to inactive pathogenic microorganisms. Chlorine dioxide (ClO2) is known as one of the most efficient disinfectants. We studied the inhibitory effect of a novel disinfectant, MA-T, for three species of bacteria (Escherichia coli, Staphylococcus aureus, and Aggregatibacter actinomycetemcomitans). We found that NADH:O2 oxidoreductase activity (NADH oxidase activity) was markedly decreased in all three species, corresponding to the decrease in colony-forming units following treatment with MA-T. In E. coli, NADH:ubiquinone-1(Q1) oxidoreductase (NADH-Q1 dehydrogenase; NDH) activity was decreased following MA-T exposure, indicating that both the NDH-1 and NDH-2 enzymes were targets of this disinfectant. The activity of ubiquinol-1 (Q1H2): O2 oxidoreductase (Q1H2 oxidase) also was decreased, indicating that cytochromes bo3 and bd were damaged by MA-T. In S. aureus, NADH-ferricyanide dehydrogenase activity and Q1H2 oxidase activity were strongly decreased, suggesting that NDH-2, cytochrome bd, and cytochrome aa3 were targets of MA-T in this species. In A. actinomycetemcomitans, only Q1H2 oxidase activity was decreased, indicating that in this species, only cytochrome bd was impaired by MA-T treatment. NADH oxidase activity in membrane vesicles prepared from untreated E. coli was not markedly affected by treatment with MA-T, suggesting that MA-T may attack components of the respiratory chain only in live bacteria (i.e., those possessing a membrane potential), because the membrane vesicles cannot produce the membrane potential.