[Catalase activity of a Pseudomonas putida strain oxidizing arsenic]

Trivalent arsenic ions added to the medium stimulated the catalase activity of a Pseudomonas putida 18 culture correlating with the rate of arsenic oxidation. As soon as the process of arsenic oxidation stopped, the activity of catalase decreased. Apparently, the production of H2O2, its decomposition by catalase and oxidation of As(III) to As(V) by the formed oxygen are a device for detoxication of trivalent arsenic acquired by the cell in the course of evolution. Therefore, oxidation of trivalent arsenic by the culture involves the peroxide mechanism.