Iodide Oxidation by a Marine Bacterium *

Abstract

S ummary . Death of euryhaline fish in an aquarium was caused by iodine liberated in seawater by a marine bacterium. The isolation of a pure culture of Pseudomonas iodooxidans sp. nov., highly resistant to iodine, led to the elucidation of the mechanism involved. Iodides were oxidized to free iodine by an extracellular peroxidase system and hydrogen peroxide was generated by the bacteria. The importance of this finding is discussed in the light of current knowledge of the iodine cycle in nature.