title: Cr(VI) reduction and Cr(III) immobilization by resting cells of Pseudomonas aeruginosa CCTCC AB93066: spectroscopic, microscopic, and mass balance analysis.
abstract: The aim of this study was to investigate the mechanism of Cr(VI) reduction and Cr(III) immobilization by resting cells of Pseudomonas aeruginosa using batch experiments and analysis techniques. Data showed that resting cells of this strain (3.2 g/L dry weight) reduced 10 mg/L of Cr(VI) by 86% in Tris-HCl buffer solution under optimized conditions of 5 g/L of sodium acetate as an electron donor, pH of 7.0 and temperature of 37 °C within 24 h. Cr(VI) was largely converted to nontoxic Cr(III), and both soluble crude cell-free extracts and membrane-associated fractions were responsible for Cr(VI) reduction. While remnant Cr(VI) existed only in the supernatant, the content of resultant Cr(III) in supernatant, on cell surface and inside cells was 2.62, 1.06, and 5.07 mg/L, respectively, which was an indicative of extracellular and intracellular reduction of chromate. Scanning electron microscopy analysis combined with energy dispersive X-ray spectroscopy revealed the adsorption of chromium on the bacterial surface. Interaction between Cr(III) and cell surface functional groups immobilized Cr(III) as indicated by Fourier transform infrared analyses and X-ray photoelectron spectroscopy. Transmission electron microscopy revealed Cr(III) precipitates in bacterial interior suggesting that Cr(II) could also be intracellularly accumulated. Thus, it can be concluded that interior and exterior surfaces of resting P. aeruginosa cells were sites for reduction and immobilization of Cr(VI) and Cr(III), respectively. This is further insight into the underlying mechanisms of microbial chromate reduction.
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Chunxi
authors.initials: C
authors.lastname: Kang
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China. pppxwu@scut.edu.cn.|The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China. pppxwu@scut.edu.cn.|Guangdong Provincial Engineering and Technology Research Centre for Environmental Risk Prevention and Emergency Disposal, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 51006, People's Republic of China. pppxwu@scut.edu.cn.|Guangdong Environmental Protection Key Lab of Solid Waste Treatment and Recycling, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China. pppxwu@scut.edu.cn.
authors.forename: Pingxiao
authors.initials: P
authors.lastname: Wu
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Liping
authors.initials: L
authors.lastname: Li
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Langfeng
authors.initials: L
authors.lastname: Yu
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Ruan
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Beini
authors.initials: B
authors.lastname: Gong
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.|The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.|Guangdong Provincial Engineering and Technology Research Centre for Environmental Risk Prevention and Emergency Disposal, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 51006, People's Republic of China.|Guangdong Environmental Protection Key Lab of Solid Waste Treatment and Recycling, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, People's Republic of China.
authors.forename: Nengwu
authors.initials: N
authors.lastname: Zhu
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D002857:Chromium / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
chemical_list: D004785:Environmental Pollutants; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Bioremediation; Chromium; Immobilization; Pseudomonas aeruginosa; Reduction