Reduction kinetics of As (V) to As (III) by a dissimilatory arsenate‐reducing bacterium, Bacillus sp. SF‐1

This study proposes a kinetic model that accounts for the toxicity of both arsenate and arsenite and characterizes the arsenate reduction ability of a dissimilatory arsenate‐reducing bacterium, Bacillus sp. SF‐1 as a bioremediation agent. The model results correlated well with a series of batch reduction experiments conducted anaerobically in serum bottles with initial arsenate concentrations of 360, 735, and 1,500 mg‐As/L. The reduction rate was expressed by the Haldane equation that describes the inhibitory effect of high concentrations of arsenate. The reduction rate constant k r , half saturation constant K S , and inhibition constant K I were estimated respectively as 1.2 × 10 9 mg‐As/cells/h, 1.5 × 10 2 mg‐As/L, and 4.2 × 10 2 mg‐As/L. Lethal effects of arsenite that is accumulated as the end‐product of arsenate reduction were expressed by the first‐order term with a lethal constant of 2.7 × 10 −4 L/mg‐As/h. The yield for the bacterial cells by arsenate respiration was estimated at 4.0 × 10 8 cells/mg‐As. © 2006 Wiley Periodicals, Inc.