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Hexavalent chromium reduction by free and immobilized cell-free extract of arthrobacter rhombi-RE
Published in
2010
PMID: 19165627
Volume: 160
   
Issue: 1
Pages: 81 - 97
Abstract
In the present study, hexavalent chromium (Cr(VI)) reduction potential of chromium reductase associated with the cell-free extracts (CFE) of Arthrobacter rhombi-RE species was evaluated. Arthrobacter rhombi-RE, an efficient Cr(VI) reducing bacterium, was enriched and isolated from a chromium-contaminated site. Chromium reductase activity of Arthrobacter rhombi-RE strain was associated with the cell-free extract and the contribution of extracellular enzymes to Cr(VI) reduction was negligible. NADH enhanced the chromium reductase activity. The enzyme activity was optimal at a pH of 5.5 and a temperature of 30 °C. Among the ten electron donors screened, sodium pyruvate was the most effective one followed by NADH and propionic acid. Michaelis-Menten constant, K m, and maximum reaction rate, V max, obtained from the Lineweaver-Burk plot were 48 μM and 4.09 nM/mg protein/min, respectively, in presence of NADH as electron donor and 170.5 μM and 4.29 nM/mg protein/min, respectively, in presence of sodium pyruvate as electron donor. Ca2+ enhanced the enzyme activity while Hg2+, Cd2+, Ba 2+, and Zn2+ inhibited the enzyme activity. Among the various immobilization matrices screened, calcium alginate beads seemed to be the most effective one. Though immobilized enzyme system was able to reduce Cr(VI), the performance was not very encouraging in continuous mode of operation. © 2009 Humana Press.
About the journal
JournalApplied Biochemistry and Biotechnology
ISSN02732289
Open AccessNo
Concepts (72)
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    ARTHROBACTER
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    CALCIUM ALGINATE BEADS
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    CELL-FREE EXTRACTS
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    CHROMIUM REDUCTASE
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    CONTAMINATED SITES
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    CONTINUOUS MODE
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    CR REDUCTIONS
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    ELECTRON DONORS
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    EXTRACELLULAR ENZYMES
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    FREE AND IMMOBILIZED CELLS
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    Hexavalent chromium
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    IMMOBILIZATION MATRICES
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    Immobilized enzyme
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    LINEWEAVER-BURK PLOTS
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    MAXIMUM REACTION RATE
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    MICHAELIS-MENTEN CONSTANT
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    Propionic acids
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    PYRUVATES
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    Reduction potential
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    Barium
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    Biodegradation
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    Bioremediation
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    Biotechnology
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    Calcium
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    Cell culture
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    Chromium
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    Chromium compounds
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    Enzymes
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    Fatty acids
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    Mercury (metal)
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    Pollution
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    Reaction rates
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    Sodium
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    Zinc
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    Enzyme activity
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    Cadmium
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    Calcium alginate
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    Mercury
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    Oxidoreductase
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    Propionic acid
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    PYRUVATE SODIUM
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    Reduced nicotinamide adenine dinucleotide
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    Unclassified drug
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    ARTHROBACTER
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    ARTHROBACTER RHOMBI-RE
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    Article
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    Bacterial strain
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    Cell free system
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    Chemical reaction kinetics
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    Electron
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    Michaelis constant
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    Nonhuman
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    pH
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    Reduction
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    Temperature
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    Alginates
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    ARTHROBACTER
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    Biodegradation, environmental
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    Bioreactors
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    Cell extracts
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    Electron transport
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    Environmental pollutants
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    Enzymes, immobilized
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    Extracellular space
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    Glucuronic acid
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    Hexuronic acids
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    Hydrogen-ion concentration
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    Kinetics
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    Oxidoreductases
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    Waste disposal, fluid
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    ARTHROBACTER RHOMBI
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    Bacteria (microorganisms)