In Vitro Reduction of Hexavalent Chromium by Cytoplasmic Fractions of Pannonibacter phragmitetus LSSE-09 under Aerobic and Anaerobic Conditions

Hexavalent chromate reductase was characterized and was found to be localized in the cytoplasmic fraction of a chromium-resistant bacterium Pannonibacter phragmitetus LSSE-09. The Cr(VI) reductase activity of cell-free extract (S 12 ) was significantly improved by external electron donors, such as N...

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Bibliographic Details
Published in:Applied biochemistry and biotechnology 2012-02, Vol.166 (4), p.933-941
Main Authors: Xu, Lin, Luo, Mingfang, Jiang, Chengying, Wei, Xuetuan, Kong, Peng, Liang, Xiangfeng, Zhao, Junmei, Yang, Liangrong, Liu, Huizhou
Format: Article
Language:English
Subjects:
Aerobiosis
Anaerobiosis
Bacteria
Bacterial Proteins - metabolism
Biochemistry
Bioengineering
Biological and medical sciences
Biotechnology
Cations - metabolism
Cell Fractionation
Chemistry
Chemistry and Materials Science
Chromium
Chromium - chemistry
Chromium - metabolism
Cytosol - chemistry
Enzymes
Fundamental and applied biological sciences. Psychology
Glucose - metabolism
Hydrogen-Ion Concentration
Kinetics
Metals, Heavy - metabolism
NAD - metabolism
Oxidation-Reduction
Oxidoreductases - metabolism
Oxygen - metabolism
Rhodobacteraceae - chemistry
Rhodobacteraceae - enzymology
Water Pollutants, Chemical - chemistry
Water Pollutants, Chemical - metabolism
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Summary:Hexavalent chromate reductase was characterized and was found to be localized in the cytoplasmic fraction of a chromium-resistant bacterium Pannonibacter phragmitetus LSSE-09. The Cr(VI) reductase activity of cell-free extract (S 12 ) was significantly improved by external electron donors, such as NADH, glucose, acetate, formate, citrate, pyruvate, and lactate. The reductase activity was optimal at pH 7.0 with NADH as the electron donor. The aerobic and anaerobic Cr(VI)-reduction enhanced by 0.1 mM NADH were respectively 3.5 and 3.4 times as high as that without adding NADH. The Cr(VI) reductase activity was inhibited by Mn 2+ , Cd 2+ , Fe 3+ , and Hg 2+ , whereas Cu 2+ enhanced the chromate reductase activity by 29% aerobically and 33% anaerobically. The aerobic and anaerobic specific Michaelis–Menten constant K m of S 12 fraction was estimated to be 64.95 and 47.65 μmol L −1 , respectively. The soluble S 150 fractions showed similar activity to S 12 and could reduce 39.7% and 53.4% of Cr(VI) after 1 h of incubation aerobically and anaerobically while the periplasmic contents showed no obvious reduction activity, suggesting an effective enzymatic mechanism of Cr(VI) reduction in the cytoplasmic fractions of the bacterium. Results suggest that the enzymatic reduction of Cr(VI) could be useful for Cr(VI) detoxification in wastewater.
ISSN:0273-2289
1559-0291
DOI:10.1007/s12010-011-9481-y