Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 stimulated with external electron donors under alkaline conditions

A novel Cr (VI) resistant bacterial strain LSSE-09, identified as Pannonibacter phragmitetus, was isolated from industrial sludge. It has strong aerobic and anaerobic Cr (VD-reduction potential under alkaline conditions. At 37 degrees C and pH 9.0, growing cells of strain LSSE-09 could completely reduce 100 and 1000 mg L-1 Cr (VI)-Cr (III) within 9 and 24h, respectively under aerobic condition. Resting cells showed higher anaerobic reduction potential with the rate of 1.46 mg g((dry weight))(-1) min(-1), comparing with their aerobic reduction rate, 0.21 mg g(-1) min(-1). External electron donors, such as lactate, acetate, formate, pyruvate, citrate and glucose could highly increase the reduction rate, especially for aerobic reduction. The presence of 3000 mg V acetate enhanced anaerobic and aerobic Cr (VI)-reduction rates up to 9.47 mg g(-1) min(-1), and 4.42 mg g(-1) min(-1), respectively, which were 5 and 20 times faster than those without it. Strain LSSE-09 retained high activities over six batch cycles and NO3- and SO42- had slightly negative effects on Cr (VI)-reduction rates. The results suggest that strain LSSE-09 has potential application for Cr (VI) detoxification in alkaline wastewater. (C) 2010 Elsevier B.V. All rights reserved.