[Autotrophic arsenic oxidation by a Pseudomonas arsenitoxidans culture]

A microorganism oxidizing As(III) to As(V) was isolated from the water of a gold-arsenic deposit; the process occurs under the autotrophic conditions. The microorganism is a motile Gram-negative rod with one flagellum. It does not assimilate organic carbon sources and grows in a mineral medium with 1.3 g of As(III) per litre and acidification of the medium from the pH 7.5-8 to 4.5. The source of nitrogen for the growth is ammonium salts, the source of phosphorous is KH2PO4. It can assimilate up to 41.2-41.7% of the carbon from carbonates as was shown using labeled carbon. The organism is capable of changing the crystal structure of arsenopyrite. In its physiologo-biochemical properties, the organism does not resemble any species described by Bergey (1975) and therefore referred to as Pseudomonas arsenitoxidans.