title: Interaction of Cr(VI) reduction and denitrification by strain Pseudomonas aeruginosa PCN-2 under aerobic conditions.
abstract: Inhibition of efficient denitrification in presence of toxic heavy metals is one of the current problems encountered in municipal wastewater treatment plants. This paper presents how to remove hexavalent chromium (Cr(VI)) and nitrate simultaneously by the novel strain Pseudomonas aeruginosa PCN-2 under aerobic conditions. The capability of strain PCN-2 for Cr(VI) and nitrate reduction was confirmed by PCR analysis of gene ChrR, napA, nirS, cnorB, nosZ, while Cr(VI) reduction was proved via an initial single-electron transfer through Cr(V) detection using electron paramagnetic resonance. Experimental results demonstrated that Cr(VI) and nitrate reduction by strain PCN-2 was much faster at pH 8-9 and higher initial cell concentration. However, increasing Cr(VI) concentration would inhibit aerobic denitrification process and result in an significant delay of nitrate reduction or N2O accumulation, which was attributed to competition between three electron acceptors, i.e., Cr(VI), O2 and nitrate in the electron transport chain.
authors: Shenzhen Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China; Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
authors: Da
authors: D
authors: He
authors: Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
authors: Maosheng
authors: M
authors: Zheng
authors: Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
authors: Tao
authors: T
authors: Ma
authors: Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
authors: Can
authors: C
authors: Li
authors: Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China. Electronic address: nijinren@iee.pku.edu.cn.
authors: Jinren
authors: J
authors: Ni
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D058440:Denitrification; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D009566:Nitrates / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009566:Nitrates; D010087:Oxides; D012336:RNA, Ribosomal, 16S; D002857:Chromium; C074702:chromium hexavalent ion; D009584:Nitrogen; D010100:Oxygen
keywords: Aerobic denitrification; Cr(VI) reduction; Electron competition; Pseudomonas aeruginosa