Contact

Dr. Johannes Raff

Head Biogeochemistry
j.raffhzdr.de
Phone: +49 351 260 2951

Social Media

Department of Biogeochemistry

Research

In the environment physical, chemical and biological processes influence the migration behavior of long-lived radionuclides (RN). In the biosphere mainly prokaryotic and eukaryotic microorganisms are involved in element cycles and the mobilization or immobilization of many radioactive and non-radioactive elements. Furthermore, their physiology and biochemistry are optimized to allow them to live and survive in almost all environments existing on earth even over long periods of time. Besides that, the interaction of radionuclides with microbes and higher organisms determine the fate of the radionuclides in nature and in the end their potential threat to human health. The aim of the research in the Department of Biogeochemistry is to identify dominating processes in the ecosphere including the food chain, to understand the biochemistry of the processes on a molecular level and to estimate their relevance for the radionuclide migration and transfer not only in nature but also in an engineered subsurface e.g. a deep-geological repository for radioactive waste. Beside the fundamental research it is also intended to generate thermodynamic data to improve the safety assessment modelling.

Current research topics

Working fields of the departement of biogeochemistry at the Institute of Resource Ecology (EN) ©Copyright: Dr. Matschiavelli, Nicole

Determination of the microbial diversity in water and soil environments contaminated with heavy metals and radionuclides as well as in different host rocks for potential radioactive waste disposals
Microbe-radionuclide-interactions with reference strains and isolates
Interaction of eukaryotic cells with radionuclides and lanthanides in particular with plants, fungi, sponges and algae
Investigation of the interaction of selected bioligands and model compounds with f-elements
Characterization of microbial processes affecting the conditions in deep geological repositories for radioactive waste (e.g. transformation of bentonite as barrier material)
Calculation and determination of the metal speciation relevant to the environment
Verification and validation of transport models
Characterization of particles in the environment relevant to the transport of radionuclides
Investigation of the transport processes of radionuclides by particles (including microbes) in natural water

Latest Publication

Europium(III) as luminescence probe for interactions of a sulfate-reducing microorganism with potentially toxic metals

Hilpmann, S.; Moll, H.; Drobot, B.; Vogel, M.; Hübner, R.; Stumpf, T.; Cherkouk, A.

Microorganisms show a high affinity for trivalent actinides and lanthanides, which play an important role in the safe disposal of high-level radioactive waste as well as in the mining of various rare earth elements. The interaction of the lanthanide Eu(III) with the sulfate-reducing microorganism Desulfosporosinus hippei DSM 8344T, a representative of the genus Desulfosporosinus that naturally occurs in clay rock and bentonite, was in-vestigated. Eu(III) is often used as a non-radioactive analogue for the trivalent actinides Pu(III), Am(III), and Cm(III), which contribute to a major part of the radiotoxicity of the nuclear waste. D. hippei DSM 8344T showed a weak interaction with Eu(III), most likely due to a complexation with lactate in artificial Opalinus Clay pore water. Hence, a low removal of the lanthanide from the supernatant was observed. Scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed a bioprecipitation of Eu(III) with phosphates potentially excreted from the cells. This demonstrates that the ongoing interaction mechanisms are more complex than a sim-ple biosorption process. The bioprecipitation was also verified by luminescence spec-troscopy, which showed that the formation of the Eu(III) phosphate compounds starts almost immediately after the addition of the cells. Moreover, chemical microscopy pro-vided information on the local distribution of the different Eu(III) species in the formed cell aggregates. These results provide first insights into the interaction mechanisms of Eu(III) with sulfate-reducing bacteria and contribute to a comprehensive safety concept for a high-level radioactive waste repository, as well as to a better understanding of the fate of heavy metals (especially rare earth elements) in the environment.

Keywords: Europium(III) luminescence; Sulfate-reducing bacteria; Europium(III) bioprecipitation; Opalinus Clay pore water

Related publications

Data publication: Europium(III) as luminescence probe for interactions of a …
ROBIS: 37168 HZDR-primary research data are used by this (Id 37162) publication
Data publication: Europium(III) as luminescence probe for interactions of a …
RODARE: 2357 HZDR-primary research data are used by this (Id 37162) publication

Ecotoxicology and Environmental Safety 264(2023), 115474
DOI: 10.1016/j.ecoenv.2023.115474

Experimental methods

Spectroscopy: LIFS (TRLFS, LIPAS); continuous wave fluorescence spectroscopy, UV-vis-NIR, XAS, Raman, ATR-FT-IR, NMR
Molecular biology (DNA extraction, PCR, Sanger sequencing, Next Generation Sequencing, heterologous expression of proteins)
Aerobic and anaerobic lab-scale cultivation of microorganisms in bioreactors (1-50 L)
Plant cell cultivation
Cell disruption in small and large volumes (mixer mill, ultra-sonic disruption, bead ruptor, high pressure homogenizer)
Microscopy: CLSM, REM, TEM, AFM, light and fluorescence microscopy
Chromatography: HPLC, FPLC
Protein biochemistry (isolation and characterization)

Projects

MIND, EU project, grant agreement No 661880, duration 01.06.2015 – 31.05.2019
BioVeStRa, BMBF support code 02S9276A, duration 01.06.2016-31.05.2019
CONCERT: European Joint Programme for the Integration of Radiation Protection Research; EC-Project grant agreement No 662287, duration 2015 -2020
TransAqua, BMBF support code 02NUK030F, duration 01.06.2013-30.11.2017
UMB project, BMWI support code 02E11344B, duration 01.04.2015-31.12.2017
BioNEWS, BMBF support code 03WKCL03F, duration 01.01.2015-31.12.2017
TRANS-LARA, BMBF support code 02NUK051B, duration 01.09.2017-28.02.2021
iCROSS, HGF/BMBF support codes SO-093 and 02NUK053B, duration 01.07.2018-30.06.2021
RadoNorm: Towards effective radiation protection based on improved scientific evidence and social considerations - focus on radon and NORM; EC Project, grant agreement No. 900009, 01.09.2020-31.08.2025
EURAD-MAGIC – NEA/EU-Projekt, duration 01.06.2019-31.05.2024
Ultrasens (WIPANO), BMWi support code 03THWSN004, duration 01.07.2020-31.10.2021
UMB II, BMWi support code 02E11870B, duration 01.01.2021-31.12.2023
EURAD-ConCorD – NEA/EU project, duration 01.06.2021-31.05.2024
RENA/ BMBF support code 02NUK066A, duration 01.09.2021-31.08.2024
PepTight/BMBFsupport code 031B1122A, duration 01.09.2021-31.08.2024
TRAVARIS/BMBF Projekt, Förderkennzeichen 15S9437C, Laufzeit 01.11.2022-31.10.2025

Team

Foto: Gruppenbild der Abteilung Biogeochemie des Instituts für Ressourcenökologie ©Copyright: Dr. Johannes Raff

Name	Bld./Office	+49 351 260	Email
Head
Dr. Johannes Raff	801/P314	2951	j.raffhzdr.de
Employees
Name	Bld./Office	+49 351 260	Email
Dr. Björn Drobot	801/P317	2895	b.drobothzdr.de
Katrin Flemming	801/P309	2958	k.flemminghzdr.de
Dr. Alix Günther	801/P256	2433 2522	a.guentherhzdr.de
Max Klotzsche	801/P306	3241	m.klotzschehzdr.de
Dr. Evelyn Krawczyk-Bärsch	801/P252	2076	e.krawczyk-baerschhzdr.de
Raul Eduardo Linares Jimenez	801/P205	2438	r.linares-jimenezhzdr.de
Dr. Henry Moll	801/P256	2433 2549	h.mollhzdr.de
Dr. Susanne Sachs	801/P208	2436	s.sachshzdr.de
Jana Seibt	801/P219	3194 2510	j.seibthzdr.de
Dr. Robin Steudtner	801/P317	2895	r.steudtnerhzdr.de
MICRONUC
Name	Bld./Office	+49 351 260	Email
Dr. Andrea Cherkouk	801/P356	2989	a.cherkoukhzdr.de
Dr. Ting-Shyang Wei	801/P318	2860	t.weihzdr.de