HR: 0800h
AN: B31D-0625    [Abstracts]
TI: Size Distributions and Morphologies of Synthetic and Biogenic Magnetite Nanoparticles
AU: * Posfai, M
EM: posfaim@almos.vein.hu
AF: Dept. of Earth and Environmental Sciences, University of Pannonia, POB 158, Veszprem, H8200, Hungary
AU: Kosa, I
EM: kosaili@gmail.com
AF: Dept. of Earth and Environmental Sciences, University of Pannonia, POB 158, Veszprem, H8200, Hungary
AU: Csakberenyi Nagy, D
EM: dorottka@gmail.com
AF: Dept. of Earth and Environmental Sciences, University of Pannonia, POB 158, Veszprem, H8200, Hungary
AU: Faivre, D
EM: Damien.Faivre@mpikg.mpg.de
AF: Max Planck Institute of Colloids and Interfaces, Wissenschaftspark Golm, Potsdam, 14424, Germany
AU: Menguy, N
EM: Nicolas.Menguy@impmc.jussieu.fr
AF: Institut de Mineralogie et Physique des Milieux Condenses, CNRS, Universite Paris 6 et 7, 140 rue de Lourmel, Paris, 75015, France
AU: Schuler, D
EM: dirk.schueler@lrz.uni-muenchen.de
AF: Dept. of Biology, Ludwig Maximilians-Universitat, Maria-Ward-Str. 1a, Munchen, 80638, Germany
AB: Magnetite crystals formed in the cells of magnetotactic bacteria have narrow size distributions and distinct, strain- specific morphologies. In order to better understand the processes that result in such specific physical properties, we studied the development of nanocrystal sizes and shapes both in cultured cells of magnetotactic bacteria and in abiotic crystal nucleation and growth experiments. Magnetite nucleation and growth was induced in resting, iron-starved cells of Magnetospirillum gryphiswaldense. Freshly induced particles have a normal size distribution and irregular morphologies. As the particles grow, their size distribution changes but remains positively skewed, in contrast to the typically negatively-skewed distribution of magnetite in continuously iron-supplemented, reference cells. The morphologies of the fast-grown magnetite crystals differ from those formed in the reference cells, indicating that the uptake rate of iron can influence the sizes and morphologies of biogenic magnetite nanoparticles. We synthesized magnetite nanoparticles by co-precipitating ferrous and ferric ions from aqueous solutions. By varying the temperature and the types and concentrations of the reagents, we controlled the mean size of the crystals from 10 to 69 nm. Adding phosphate to the solution resulted in irregular morphologies, whereas the nucleation of crystals on synthetic bacterial filaments produced a bimodal size distribution and slightly more regular morphologies. Experiments are being conducted with various organic additives, with the ultimate goal of being able to reproduce the specificity of crystal sizes and shapes observed in magnetotactic bacteria.
DE: 0419 Biomineralization
DE: 0424 Biosignatures and proxies
DE: 0463 Microbe/mineral interactions
SC: Biogeosciences [B]
MN: 2007 Fall Meeting