Role of extracellular compounds in Cd-sequestration relative to Cd uptake by bacterium Sinorhizobium meliloti.
The role of bacterially derived compounds in Cd(II) complexation and uptake by bacterium Sinorhizobium meliloti wild type (WT) and genetically modified ExoY-mutant, deficient in exopolysaccharide production, was explored combining chemical speciation measurements and assays with living bacteria. Obtained results demonstrated that WT- and ExoY-strains excreted siderophores in comparable amounts, while WT-strain produced much higher amount of exopolysaccharides and less exoproteins. An evaluation of Cd(II) distribution in bacterial suspensions under short term exposure conditions, showed that most of the Cd is bound to bacterial surface envelope, including Cd bound to the cell wall and to the attached extracellular polymeric substances. However, the amount of Cd bound to the dissolved extracellular compounds increases at high Cd(II) concentrations. The implications of these findings to more general understanding of the Cd(II) fate and cycling in the environment is discussed.
Slaveykova
Vera I
VI
Environmental Biophysical Chemistry, IIE-ENAC, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 2, CH-1015 Lausanne, Switzerland. vera.slaveykova@epfl.ch
Parthasarathy
Nalini
N
Dedieu
Karine
K
Toescher
Denis
D
D001673:Biodegradation, Environmental; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity
D012989:Soil Pollutants; D002104:Cadmium