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 10 mM) and selenite almost completely (up to 9 mM). In addition, higher concentrations of selenate and selenite were substantially reduced. Activity was observed under the following experimental conditions: 20-50 degrees C, pH 7-9, and 0.05-20 g L-1 NaCl for selenate reduction, and 20-50 degrees C, pH 6-9, and 0.05-50 g 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. (C) 2011, The Society for Biotechnology, Japan. All rights reserved.