Characterization of Pseudomonas stutzeri NT-I capable of removing soluble selenium from the aqueous phase under aerobic conditions.

Pseudomonas stutzeri strain NT-I was isolated from the drainage wastewater of a selenium refinery plant. This bacterium efficiently reduced selenate to elemental selenium without prolonged accumulation of selenite under aerobic conditions. Strain NT-I was able to reduce selenate completely at high concentrations (up to 10mM) and selenite almost completely (up to 9mM). In addition, higher concentrations of selenate and selenite were substantially reduced. Activity was observed under the following experimental conditions: 20–50°C, pH 7–9, and 0.05–20g L–1 NaCl for selenate reduction, and 20–50°C, pH 6–9, and 0.05–50g L–1 NaCl for selenite reduction. Under anaerobic conditions, selenate was reduced more rapidly, whereas selenite was not reduced at all. The high selenate- and selenite-reducing capability at high concentrations suggested that strain NT-I is suitable for the removal of selenium from high-strength industrial wastewater.