Franco Baldi (Author), Michele Gallo (Author), Salvatore Daniele (Author), Dario Battistella (Author), Claudia Faleri (Author), Alojz Kodre (Author), Iztok Arčon (Author)

Abstract

A strain of Klebsiella oxytoca DSM 29614 is grown on sodium citrate in the presence of 50 mg l−1 of Hg as Hg(NO3)2. During growth, the strain produces an extracellular polymeric substance (EPS), constituted by a mixture of proteins and a specific exopolysaccharide. The protein components, derived from the outer membrane of cells, are co-extracted with the extracellular exopolysaccharide using ethanol. The extracted EPS contains 7.5% of Hg (total amount). This indicates that EPS is an excellent material for the biosorption of Hg2+, through chemical complexation with the EPS components. The binding capacity of these species towards Hg2+ is studied by cyclic voltammetry, and Hg L3-edge XANES and EXAFS spectroscopy. The results found indicate that Hg2+ is mainly bound to the nitrogen of the imidazole ring or other N-heterocycle compounds. The hydroxyl moities of sugars and/or the carboxyl groups of two glucuronic acids in the polysaccharide can also play an important role in sequestring Hg2+ ions. However, N-heterocyclic groups of proteins bind Hg2+ faster than hydroxyl and carboxyl groups of the polysaccharide.

Keywords

Klebsiella oxytoca;biosorption;proteins;polysaccharide;cyclic voltammetry;EXAFS analysis;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UNG - University of Nova Gorica
UDC: 546
COBISS: 4706811 Link will open in a new window
ISSN: 0045-6535
Views: 3916
Downloads: 0
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Other data

URN: URN:SI:UNG
Type (COBISS): Not categorized
Pages: str. 296-304
Issue: ǂVol. ǂ176
Chronology: Jun. 2017
DOI: 10.1016/j.chemosphere.2017.02.093
ID: 9585661