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Bioresour Technol. 2012 Nov;123:713-6. doi: 10.1016/j.biortech.2012.07.090. Epub 2012 Jul 31.

Reduction of Cr(VI) by Escherichia coli BL21 in the presence of redox mediators.

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  • 1School of Environmental Science and Engineering, Hebei University of Science and Technology, Yuhua East Road 70#, Shijiazhuang 050018, China.


Anthraquinone-2,7-disulfonate (2,7-AQDS), anthraquinone-1-sulfonate (α-AQS), anthraquinone-2-sulfonate (AQS), anthraquinone-2,6-disulfonate (AQDS) and anthraquinone-1,5-disulfonate (1,5-AQDS) were selected as redox mediators for Cr(VI) reduction by Escherichia coli BL21. In the presence of 0.8mmoll(-1) AQS, the Cr(VI) reduction efficiency was 98.5% in 7.5h, whereas it was only 21-34% in the absence of a mediator or in the presence of α-AQS, 1,5-AQDS, AQDS, 2,7-AQDS. A linear correlation, k=0.768C(AQS)+1.5531 (R(2)=0.9935), was found for the reaction constant, k (mg Cr(VI) g(-1) dry cell weight h(-1)) and the AQS concentration (C(AQS)). The Arrhenius equation described the Cr(VI) reduction in the tested temperature range, and the pre-exponential factor A was 13.249mg Cr(VI) g(-1) dry cell weight h(-1),and the activation energy Ea was 28.01kJmol(-1). Glucose was the best carbon sources, and the optimum pH was 6.0. The Cr(VI) reduction rate obtained with AQS is a significant improvement over low conventional anaerobic reduction rates.

Copyright © 2012 Elsevier Ltd. All rights reserved.

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