Oxidation of arsenite to arsenate by a bacterium isolated from an aquatic environment

Arsenic is ubiquitous in the biosphere and frequently reported to be an env ironmental pollutant. Global cycling of arsenic is affected by microorganis ms. This paper describes a new bacterial strain which is able to efficientl y oxidize arsenite (As[III]) into arsenate (As[V]) in liquid medium. The ra te of the transformation depends on the cell density. Arsenic species were separated by high performance liquid chromatography (HFLC) and quantified b y inductively coupled plasma-atomic emission spectrometry (ICP-AES). The st rain also exhibits high minimum inhibitory concentrations (MICs) for As[III ] (6.65 mM (500 mg L-1)) and other heavy metals, such as cadmium (1.42 mM ( 160 mg L-1)) or lead (1.20 mM (250 mg L-1)). Partial identification of the strain revealed a chemoorganotrophic, Gram-negative and motile rod. The res ults presented here demonstrate that this strain could represent a good can didate for arsenic remediation in heavily polluted sites.