Oxidation of Arsenite by a Soil Isolate of Alcaligenes

A strain of Alcaligenes , isolated from soil and grown in nutrient broth in the presence of arsenite, possessed the ability to oxidize arsenite to arsenate. Washed cell suspensions consumed one‐half mol of oxygen/mol of arsenite and produced arsenate. The optimum pH for arsenite oxidation was 7.0. The K m for arsenite was 1.5 × 10 ‐4 M and V max was 6.7 μl of oxygen/min. The arsenite‐oxidizing enzyme system was induced by growth in arsenite. Response of the arsenite‐oxidizing enzyme system to respiratory inhibitors suggested that electrons resulting from arsenite oxidation by an oxido‐reductase with a bound flavin are transferred via cytochrome c and cytochrome oxidase to oxygen. The presence of the cytochromes in crude extract was confirmed by spectral measurements.