Oxidation of arsenite to arsenate by Alcaligenes faecalis.

Alcaligenes faecalis, resistant to the toxic effects of 0.01 M sodium arsenite, was isolated from raw sewage and shown to be capable of oxidizing arsenite to arsenate. When the organisms were grown in chemically defined medium, this conversion was due to the appearance at stationary phase of an intracellular, oxygen-sensitive, inducible enzyme and/or component of the electron transport system; when the organisms were grown in a nutrient broth-yeast extract medium, the enzyme appeared in the late exponential phase of growth. The presence of 0.02 M arsenite in the culture medium affected neither growth rate nor final cell yield.