Authors: Iztok Arčon Oreste Piccolo Stefano Paganelli Franco Baldi
Publish Date: 2012/05/15
Volume: 25, Issue: 5, Pages: 875-881
Abstract
A strain of Klebsiella oxytoca isolated from acid pyritemine drainage characteristically produces a ferric hydrogel consisting of branched heptasaccharide repeating units exopolysaccharide EPS with metal content of 36 wt The high content of iron in the EPS matrix cannot be explained by a simple ferric ion bond to the sugar skeleton The biogenerated Fe–EPS is investigated by Xray absorption spectroscopy Fe Kedge XANES analysis shows that iron is mostly in trivalent form with a nonnegligible amount of Fe2+ in the structure The Fe EXAFS results indicate that iron in the sample is in a mineralized form prevalently in the form of nanosized particles of iron oxides/hydroxides most probably a mixture of different nanocrystalline forms TEM shows that these nanoparticles are located in the interior of the EPS matrix as in ferritin The strain produces Fe–EPS to modulate Feions uptake from the cytoplasm to avoid iron toxicity under anaerobic conditions This microbial material is potentially applicable as iron regulatorThis research was supported by the Slovenian Research Agency P10112 Access to synchrotron radiation facilities of ELETTRA beamline XAFS is acknowledged Giuliana Aquilanti and Luca Olivi of ELETTRA are acknowledged for expert advice on beamline operation
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