title: Characterization of H+ and Cd2+ binding properties of the bacterial exopolysaccharides.
abstract: The proton and Cd binding capacities of microbially produced exopolysaccharides, EPS, were quantified by the determination of stability constants and the concentration of complexing sites using H(+) or Cd(2+) selective electrodes in dynamic titrations. The influence of ionic strength, pH and the Cd to EPS ratio was evaluated over large concentration ranges. The applicability of the non-ideal competitive adsorption isotherm combined with a Donnan electrostatics approach was tested with respect to the EPS. Proton and cadmium binding data were compared with literature data examining other ubiquitous environmental ligands including humic substances, alginate, bacteria, etc. Subsequent modelling of Cd speciation in aquatic (fresh and marine waters) and soil systems suggested that the exopolysaccharides would play non-negligible role, under most conditions. The quantitative information provided in this paper thus represents an important advance in our understanding of Cd transport, bioavailability and impact in aquatic and terrestrial systems.
authors.affiliation: Environmental Biophysical Chemistry, Environmental Science and Technology Institute, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Cristina
authors.initials: C
authors.lastname: Lamelas
authors.forename: Marc
authors.initials: M
authors.lastname: Benedetti
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Wilkinson
authors.forename: Vera I
authors.initials: VI
authors.lastname: Slaveykova
mesh_terms: D002104:Cadmium / Q000737:chemistry*; D049109:Cell Proliferation; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D011522:Protons; D016962:Sinorhizobium meliloti / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D012989:Soil Pollutants / Q000737:chemistry; D055672:Static Electricity; D017186:Titrimetry; D014867:Water / Q000737:chemistry
chemical_list: C083492:EPSI polysaccharide; D011135:Polysaccharides, Bacterial; D011522:Protons; D012989:Soil Pollutants; D002104:Cadmium; D014867:Water