Contact

Sarah Fischer
Surface Processes
sarah.fischerAthzdr.de
Phone: +49 351 260 - 2438

PhD thesis


Spectroscopic characterization of trivalent actinides americium and curium on bacterial cell walls

Pic Sarah Fischer

PhD student:
Sarah Fischer
Supervisor:
Prof. Dr. G. Bernhard, Dr. A. Barkleit, Dr. J. Raff (HZDR)
Division:
Surface processes
Period:
03/2011–02/2014


Motivation:

Microorganisms, like bacteria, show the ability to interact with metals in different ways and influence the heavy metal mobility in the environment. They evolve special strategies to survive in extreme environmental conditions.

The trivalent actinides americium and curium are minor actinides. They are components of high level nuclear waste and show very long half-life's and a high toxicity level.

Until now, the realization of nuclear waste storage has not been resolved completely. A precise nuclear safety assessment is necessary to predict reliably transport of radiotoxic elements within the humans environment. In case of incidence, i.e. when actinides are released from the disposal site, bacteria are able to influence their migration behavior.

In this work, Bacillus isolates from the uranium mining waste pile “Haberland” nearby Johanngeorgenstadt (Saxony) are used. There are gram-positive bacteria, and their binding capacities to uranium were already observed in previous studies. They have a typically cell wall composition with cytoplasmic membrane, secondary cell wall polymer, peptidoglycane and surface-layer (S-layer).


Objectives:

The aim of this study is the characterization of the binding of the trivalent actinides and of the functional groups, which form the complexes on the bacterial cell walls to understand the chemical behavior on a molecular level.

The separation of the cell wall into the different compounds of the gram-positive bacteria will be done. Intact cells and cell wall components will be incubated with trivalent actinides, americium and curium, and with the lanthanide europium, the non-radioactive analog. Spectroscopic methods like TRLFS, ATR FT-IR and EXAFS will be applied to study the complex formation.


Contact

Sarah Fischer
Surface Processes
sarah.fischerAthzdr.de
Phone: +49 351 260 - 2438