Pyridine-2,6-bis(thiocarboxylic acid) Produced by <Emphasis Type="BoldItalic">Pseudomonas stutzeri</Emphasis> KC Reduces Chromium(VI) and Precipitates Mercury,Cadmium, Lead and Arsenic |
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Authors: | Anna M Zawadzka Ronald L Crawford Andrzej J Paszczynski |
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Institution: | (1) Environmental Biotechnology Institute, University of Idaho, Food Research Center 103, P.O. Box 441052, Moscow, Idaho 83844–1052, USA |
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Abstract: | Interactions of the Pseudomonas stutzeri KC siderophore pyridine-2,6-bis(thiocarboxylic acid) (pdtc) with chromium(VI), mercury(II), cadmium(II), lead(II), and arsenic(III)
are described. Pdtc was found to reduce Cr(VI) to Cr(III) in both bacterial cultures and in abiotic reactions with chemically
synthesized pdtc. Cr(III) subsequently formed complexes with pdtc and pdtc hydrolysis products, and their presence was confirmed
using electrospray ionization-mass spectrometry (ESI-MS). Cr(III):pdtc complexes were found to slowly release Cr(III) as chromium
sulfide and possibly Cr(III) oxides. Pdtc also formed poorly soluble complexes with Hg, Cd, Pb, and As(III). Hydrolysis of
those complexes led to the formation of their respective metal sulfides as confirmed by energy dispersive X-ray spectroscopy
(EDS) elemental analysis. The pdtc-producing strain P. stutzeri KC showed higher tolerance to most of these metals as compared to a pdtc-negative mutant. A novel role of pdtc is postulated
as its involvement in providing an extracellular pool of thiols that are used for redox processes in detoxification of the
bacterial extracellular environment. These redox processes can be mediated by transition metal:pdtc complexes. |
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Keywords: | pyridine-2 6-bis(thiocarboxylic acid) pdtc chromium(VI) reduction mercury cadmium lead arsenic |
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