Sorption and precipitation of Mn2+ by viable and autoclaved Shewanella putrefaciens: Effect of contact time
KAUST Grant NumberKUK-C1-017-12
MetadataShow full item record
AbstractThe sorption of Mn(II) by viable and inactivated cells of Shewanella putrefaciens, a non-pathogenic, facultative anaerobic, gram-negative bacterium characterised as a Mn(IV) and Fe(III) reducer, was studied under aerobic conditions, as a function of pH, bacterial density and metal loading. During a short contact time (3-24h), the adsorptive behaviour of live and dead bacteria toward Mn(II) was sufficiently similar, an observation that was reflected in the studies on adsorption kinetics at various metal loadings, effects of pH, bacteria density, isotherms and drifting of pH during adsorption. Continuing the experiment for an additional 2-30days demonstrated that the Mn(II) sorption by suspensions of viable and autoclaved cells differed significantly from one another. The sorption to dead cells was characterised by a rapid equilibration and was described by an isotherm. In contrast, the sorption (uptake) to live bacteria exhibited a complex time-dependent uptake. This uptake began as adsorption and ion exchange processes followed by bioprecipitation, and it was accompanied by the formation of polymeric sugars (EPS) and the release of dissolved organic substances. FTIR, EXAFS/XANES and XPS demonstrated that manganese(II) phosphate was the main precipitate formed in 125ml batches, which is the first evidence of the ability of microbes to synthesise manganese phosphates. XPS and XANES spectra did not detect Mn(II) oxidation. Although the release of protein-like compounds by the viable bacteria increased in the presence of Mn2+ (and, by contrast, the release of carbohydrates did not change), electrochemical analyses did not indicate any aqueous complexation of Mn(II) by the organic ligands. © 2012 Elsevier Ltd.
CitationChubar N, Visser T, Avramut C, de Waard H (2013) Sorption and precipitation of Mn2+ by viable and autoclaved Shewanella putrefaciens: Effect of contact time. Geochimica et Cosmochimica Acta 100: 232–250. Available: http://dx.doi.org/10.1016/j.gca.2012.09.051.
SponsorsFinancial support from the European Union Marie Curie IIF Fellowship to N. Chubar for Utrecht University (Feb. 2006-Jan. 2008) is gratefully acknowledged (Grant No MIF1-CT-2006-021922). The EXAFS/XANES studies at Dutch-Belgian beamline BM26A of ESRF (experiment No 26-01-794) were funded by the Dutch Ministry of Scientific Research NWO (Grant No 195.068.281); Dr. S. Nikitenko is gratefully acknowledged for support during the EXAFS studies. This research was also partially funded by a King Abdullah University of Science and Technology (KAUST) Center-in-Development Award to Utrecht University (Grant No KUK-C1-017-12) via the KAUST Global Research Partnership program. We thank Dr. A. Shchukarev (Umea University, Sweden) for XPS analysis. We are also grateful to the anonymous reviewers whose comments helped us to improve the paper considerably.
JournalGeochimica et Cosmochimica Acta