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Published on: November 12, 2021
Mechanisms of gold bioaccumulation by filamentous cyanobacteria from gold(III)-chloride complex
Maggy F Lengke1, Bruce Ravel, Michael E Fleet
1Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada. mlengke@uwo.ca
Abstract:
The mechanisms of gold bioaccumulation by cyanobacteria (Plectonema boryanum UTEX 485) from gold(III)-chloride solutions have been studied at three gold concentrations (0.8,1.7, and 7.6 mM) at 25 degrees C, using both fixed-time laboratory and real-time synchrotron radiation absorption spectroscopy (XAS) experiments. Interaction of cyanobacteria with aqueous gold(III)-chloride initially promoted the precipitation of nanoparticles of amorphous gold(I)-sulfide at the cell walls, and finally deposited metallic gold in the form of octahedral (111) platelets (approximately 10 nm to 6 microm) near cell surfaces and in solutions. The XAS results confirm that the reduction mechanism of gold(III)-chloride to metallic gold by cyanobacteria involves the formation of an intermediate Au(I) species, gold(I)-sulfide.
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