The study of the effects of carbon dioxide-induced elevation of hydrogen peroxide toxicity on microbes as a novel tool for water purification

The supercritical concentration of CO₂ (SCCO₂) and a high concentration (3.0%) of molecules of hydrogen peroxide (H₂O₂) are currently being used as antiseptic and antibacterial agents. The fact that low concentrations of CO₂ have an activation effect on functional activity of microbes allows us to predict that CO₂ could elevate the toxic effect of H₂O₂ on cells. To check this hypothesis the dependency of the toxic effect of H₂O₂ on wild type of Escherichia coli K-12 on soluble concentration of CO₂ in culture media was studied. The obtained data show that culture media enriched with CO₂ leads to the increase of toxic effect of H₂O₂ on microbes at both cases when pH is constant and when it changes. So CO₂ in non-supercritical concentration could elevate the toxic effect of H₂O₂ on microbes by the activation of the metabolic processes in microbes. During the experiments we used classical microbiological methods (indirect viable cell counts or counting colony forming units (CFUs)), as well as the method of measuring hydrogen peroxide content in aqueous solution by means of enhanced chemiluminescence method in a peroxidase-luminol-p-iodophenol system. This discovery is concerning to use CO₂/H₂O₂ combination system, which could have implication in the inhibition of growth of microbes in water and the microbiological monitoring of water could provide valuable information for managing the health of exhibition of aqua ecosystems.