Arsenite oxidation and arsenate respiration by a new Thermus isolate

A new microbial strain was isolated from an arsenic-rich terrestrial geothe rmal environment. The isolate, designated HR13, was identified as a Thermus species based on 16S rDNA phylogenetic relationships and close sequence si milarity within the Thermus genus. Under aerobic conditions, Thermus HR13 w as capable of rapidly oxidizing inorganic As(III) to As(V). As(III) was oxi dized at a rate approximately 100-fold greater than abiotic rates. Metaboli c energy was not gained from the oxidation reaction. In the absence of oxyg en, Thermus HR13 grew by As(V) respiration coupled with lactate oxidation. The ability to oxidize and reduce arsenic has not been previously described within the Thermus genus. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.